This work was supported by funds from the Department of Animal and Avian Sciences to BT.

All animal experiments were approved by the Beltsville Area Animal Care and Use Comittees (BAACUC 11-015) in accordance with USDA Animal Care and Use Guidelines.
1. Anesthesia and Analgesia (Common for Both Surgical Procedures)
<ol>
	<li>Weigh the mouse and load the following anesthetics and analgesic in two 1 ml syringes with 27 G needles:
	<ol>
		<li>Ketamine (0.1 mg/g: 0.01 ml/g of a 10 mg/ml solution) and xylazine (0.01 mg/g: 0.005 ml/g of a 2 mg/ml solution).</li>
		<li>Buprenorphine (0.1 &#956;g/g: 0.01 ml of a 0.01 mg/ml solution).</li>
	</ol>
	</li>
	<li>Immobilize the mouse by picking up the scruff of its neck as close to the jaws as possible with the thumb and index fingers and holding the tail between the little and ring fingers.</li>
	<li>Inject Ketamine-Xylazine mixture intraperitoneally. In order to avoid puncturing internal organs, hold the mouse with its head slightly below the level of its hips (Figure&#160;1A)</li>
	<li>Inject Buprenorphine subcutaneously in the scruff of neck hold between the thumb and index fingers (Figure&#160;1B).</li>
	<li>Leave the mouse in the cage (clean and without any other animal) on a warm stage.</li>
	<li>Once unconscious, check for the absence of rear foot reflex (checked by toe pinch). Apply eye ointment to avoid dryness of the eye and to check for the absence of palpebral reflex (Figure&#160;1C).</li>
	<li>This protocol provides a surgical anesthesia plane for a minimum of 30 min, enough to perform the procedures described below (Protocols&#160;2 and 3). If longer times are required, an additional injection of ketamine + xylazine with half of the dosage described in 1.1.1 can be applied after 30 min. A change in the breathing pattern to a faster and irregular one indicates the loss of the proper anesthesia plane.</li>
</ol>
2. Vasectomy
<ol>
	<li>Use a male with a proven mating performance.</li>
	<li>Sterilize surgical instruments, clean the surfaces where surgery will be performed and wipe them with 70% ethanol.</li>
	<li>Perform anesthesia as previously detailed (Protocol 1), checking for loss of reflexes.</li>
	<li>Place the mouse on a warm stage, remove fur with electric clippers from the ventral area between two imaginary transversal lines placed 0.5 cm and 2.5 cm above the penis (Figure&#160;2A).</li>
	<li>Sanitize the shaved area by sequential wiping with 10% povidone iodine and 70% ethanol.</li>
	<li>Place the mouse in supine position with its tail towards the surgeon and cover with a sterile towel with a hole exposing the shaved area. Illuminate the surgical area.</li>
	<li>Perform a 10-15 mm longitudinal skin incision in the medial line of the abdomen, about 1 cm above the penis. Hold the skin with dressing serrated forceps and then cut with scissors (Figures&#160;2A and&#160;2B).</li>
	<li>Perform a 5-10 mm longitudinal incision in the linea alba. Hold the muscle with microdissecting serrated forceps and cut with scissors (Figure&#160;2C).</li>
	<li>Grab the testicular adipose pad of one side with micro dissecting serrated forceps and pull it to expose testis, vas deferens and epididymis. Vas deferens is located medial to the testis and it is a clearly distinguishable free tube (not attached to the testis wall like the epididymis) with a blood vessel running along one side (Figure&#160;2D).</li>
	<li>Holding the vas deferens with a micro dissecting serrated forceps, flame dressing forceps until they turn red (Figure&#160;2E), and then use them to cut and cauterize the vas deferens in two points at once (Figure&#160;2F). The cut should remove a portion of about 5 mm and leave two clearly separated cauterized ends (Figure&#160;2G).</li>
	<li>Move the testicle, epididymis and vas deferens back to the abdominal cavity.</li>
	<li>Proceed from step 9 in the other testicle.</li>
	<li>Suture the muscle with one or two horizontal mattress stitches made with 5/0 absorbable suture (Figure&#160;2H).</li>
	<li>Suture the skin with one or two wound clippers (Figure&#160;2I).</li>
	<li>Identify the vasectomised male (ear ring, finger tattoo&#8230;), move it the cage placed on a warm stage and observe until it recovers from anesthesia (conscious and maintain sternal recumbency). A 0.5-1 ml subcutaneous injection of warm saline solution improves recovery. Record the possible incidences occurring during vasectomy transfer, add antibiotic to the drinking water.</li>
	<li>Wound clips can be removed 10 days after vasectomy with a wound clipper remover or a pair of teeth forceps. The vasectomized male will be ready to mate 2 weeks after surgery.</li>
	<li>Test the infertility of the vasectomized male by mating with fertile females before using it to obtain recipients.</li>
</ol>
3. Utero-tubal Embryo Transfer
<ol>
	<li>Mouse morulae or blastocysts can be transferred by this technique to a pseudopregnant recipient female at 2.5 dpc.</li>
	<li>Prepare embryo manipulation glass pipette:
	<ol>
		<li>Polish the tips of the glass capillaries in order to avoid damaging the pipette holder.</li>
		<li>Soften a middle portion of the glass capillary by heating with a fine flame while slightly rotating the capillary with both hands synchronously. Once the capillary section becomes soft and malleable (light red color), withdraw it quickly from the flame and pull both ends to narrow its external diameter to 130-150 &#956;m.</li>
		<li>Wait for the glass to cool down and then cut it by lightly scoring the narrow part with a diamond-point pencil, abrasive stone or nail file and pulling from both sides. The break should be clean and perpendicular</li>
	</ol>
	</li>
	<li>Polish the tip by very quickly flaming, leaving a 100-130 &#956;m aperture. Pipettes can be stored for later use.</li>
	<li>Warm embryo manipulation media (CZBH or M2, see discussion).</li>
	<li>Sterilize surgical instruments, clean the surfaces where surgery will be performed and wipe them with 70% ethanol.</li>
	<li>Perform anesthesia as previously detailed (Protocol 1), checking for loss of reflexes.</li>
	<li>Keeping the mouse on a warm stage, remove fur with electric clippers from the dorsal area between the knees and the distal ribs (Figures 3A and&#160;3B).</li>
	<li>Sanitize the shaved area by sequential wiping with 10% povidone iodine and 70% ethanol.</li>
	<li>Move the embryos from the incubator to the prewarmed embryo manipulation media.</li>
	<li>Move the recipient to a warm stage under the stereomicroscope and place it in prone position laterally to the surgeon (with its head looking to the right or left side of the surgeon).</li>
	<li>Cover the area with a sterile towel with a hole exposing the shaved area and illuminate the surgical area.</li>
	<li>Perform a 1 cm transversal (vertical) incision in the skin in a spot located on the cranial &#8531; of the line between the last rib and the hips and the dorsal &#8531; of the line between the back and the abdomen (Figures 3A and&#160;3B). Hold the skin with dressing serrated forceps and cut with scissors (Figure&#160;3C).</li>
	<li>Once the skin has been cut, ovary (red/orange) or the adipose pad surrounding the ovary (white) can be visualized through the body wall. Perform a 0.3-0.5 cm transversal (vertical) incision in the body wall over the ovary or adipose pad in a spot where the incision does not cut any large blood vessel. Hold the muscle with micro dissecting serrated forceps and cut with scissors (Figure&#160;3D).</li>
	<li>Move the mouse to have its head facing towards the surgeon.</li>
	<li>Load the embryo manipulation pipette (Figure&#160;3E):
	<ol>
		<li>Allow CZBH media to ascend by capillarity through the narrow portion of the manipulation pipette until about 5 mm of the wider part.</li>
		<li>Take up a small air bubble (0.2-0.5 mm).</li>
		<li>Introduce the embryos (5-10) in a minimal amount of media (2-4 mm).</li>
		<li>Take up another small air bubble (0.2-0.5 mm) and a small amount of media (0.5-1 mm).</li>
		<li>Leave the glass pipette attached to the mouth aspirator holder or to the hand-operated device, ready for step 3.17.</li>
	</ol>
	</li>
	<li>Grab the adipose pad surrounding the ovary with micro dissecting serrated forceps and pull it towards the mouse head to expose the ovary, oviduct, and a small portion of the upper uterus out of the abdominal cavity (Figures 3F and&#160;3G).</li>
	<li>Holding the aspirator mouth piece in the mouth, ready to be used, grab the adipose pad with micro dissecting serrated forceps to move the oviduct and expose the utero-tubal junction (i.e. where the oviduct meets the uterus).</li>
	<li>Keeping the utero-tubal junction accessible, take slight curved micro dissection forceps with your left hand (if right handed) and place them just below the utero-tubal junction grabbing the oviduct about 2 mm above that portion.</li>
	<li>Holding the utero-tubal junction with the slight curved micro dissection forceps, puncture the oviduct section close to the forceps with a 27 G needle (Figure 3H).</li>
	<li>Insert the embryo manipulation pipette into the orifice performed with the needle and advance to the uterus through the utero-tubal junction (Figures 3I and&#160;3J). Once the pipette has passed the utero-tubal junction (Figure&#160;3K) it slides easily. Do not progress very far into the uterus to prevent endometrial damage (no more than 3 mm) and pipette blocking by the debris.</li>
	<li>Release the embryos into the uterus by gently blowing (Figure&#160;3L). Both air bubbles must pass through the uterus. Some of the media above the first bubble may also be released into the uterus, but avoid introducing more air, as it may impede implantation.</li>
	<li>Remove the pipette just after embryos have been released into the uterus.</li>
	<li>Move the oviduct and ovary back to the abdominal cavity by grabbing the adipose pad.</li>
	<li>Suture the muscle with a horizontal mattress stitch with 5/0 absorbable suture (Figure&#160;3M).</li>
	<li>Suture the skin with a wound clipper (Figure&#160;3N).</li>
	<li>Proceed from step 10 on the other side if required.</li>
	<li>Identify the recipient (ear ring, finger tattoo&#8230;), move it to its cage (placed on a warm stage) and observe until it recovers from anesthesia (conscious and maintain sternal recumbency).</li>
	<li>Annotate the possible incidences occurring during embryo transfer and add antibiotic to the drinking water. A 0.5-1 ml subcutaneous injection of warm saline solution improves recovery.</li>
	<li>Wound clips can be removed 10 days after embryo transfer with a wound clipper remover or two pairs of forceps (Figure&#160;3O). The recipient can be weighed on that day to assess pregnancy and estimate the number of pups. Provide nestling material to the recipient 15 days after embryo transfer.</li>
</ol>

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G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fertilization+of+mouse+eggs+in+vitro.">Fertilization of mouse eggs in vitro.</a> Nature. 220, 592-593 (1968).</li><li>McLaren, A., Biggers, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Successful+development+and+birth+of+mice+cultivated+in+vitro+as+early+as+early+embryos.">Successful development and birth of mice cultivated in vitro as early as early embryos.</a> Nature. 182, 877-878 (1958).</li><li>McLaren, A., Michie, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studies+on+the+transfer+of+fertilized+mouse+eggs+to+uterine+foster-mothers.+I.+Factors+affecting+the+implantation+and+survival+of+native+and+transferred+eggs.">Studies on the transfer of fertilized mouse eggs to uterine foster-mothers. I. Factors affecting the implantation and survival of native and transferred eggs.</a> J. Exp. 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The authors declare no competing financial interests.

Vasectomy is a relatively straight forward surgical technique that does not involve major difficulties. When sanitizing with povidone iodine and ethanol make sure that the last wash (with ethanol) removes povidone iodine, as it may irritate the peritoneum. The access to vas deferens can also be achieved by the scrotum or performing a transversal incision in the abdomen8. Scrotal incision has been recommended to transversal abdominal incision due to the comparatively smaller incision needed and slightl...

Embryo transfer is probably the most frequent surgical procedure performed in the mouse model. This technique is essential to obtain offspring from embryos subjected to in vitro manipulation techniques and, therefore, constitutes a necessary step for the development of genetically modified models by pronuclear injection, lentiviral transduction, or chimera formation. Besides, the technique allows the study of the developmental effects of diverse insults occurring during preimplantation development. The use of artificial reproduction techniques1 or the exposure to abnormal concentrations of different substances or metabolites2 may affect embryo development resulting in implantation or placentation failures and long term effects in the offspring. A reliable and reproducible embryo transfer technique is crucial to test the possible negative effects of the experimental treatment on implantation and fetal development in a consistent manner.
Murine preimplantation embryos can be transferred to a recipient female either into the oviduct via the ampullae of 0.5 days post coitum (dpc) pseudopregnant recipients (oviduct transfer)3,4 or into the uterus of 2.5 dpc pseudopregnant recipient (uterine transfer)5,6 depending on their developmental stage. Embryos at the blastocyst stage, such as those used to generate chimeric mice by injection of embryonic or induced pluripotent stem cells, are usually transferred by uterine transfer. Blastocysts can also be transferred to the oviduct of a 0.5 dpc recipient, but it constitutes a less physiological test for developmental disruptors, because the embryo undergoes diapause and has 2 days to recover from the insult before implantation takes place. Uterine transfer involves puncturing the uterine wall with a narrow needle in order to generate an aperture that allows the access of an embryo manipulation pipette into the uterine lumen. Although this technique can yield good results, the survival to term (i.e. the percentage of embryos transferred that develop to a pup) is often low and unpredictable7,8.
The puncture of the uterine wall entails some detrimental side effects. First, myometrium is a highly vascularized tissue and its puncture often results in a small hemorrhage. Blood may block the embryo transfer pipette or invade the uterine lumen causing embryonic death and/or implantation failure. This is particularly relevant when embryos without zona are transferred, as the blood cells and debris can attach to the blastomeres. Second, the opening performed does not seal after the embryos have been transferred, so they can flow back through the orifice and be expelled to the abdominal cavity when a too large volume has been introduce into the uterus. The utero-tubal embryo transfer described herein take advantage of the utero-tubal junction to deliver the embryos into the uterus without the need of puncturing the uterine wall and thereby avoiding its adverse consequences9.
The pseudopregnant recipient females used for embryo transfer are obtained by natural mating with vasectomized males8. The seminal secretions produced by a sterile male are required for the uterus to become receptive to the transferred embryos. To obtain a recipient, a maximum of 2 females of 8 weeks to 6 months of age are placed with a vasectomized male in the afternoon. The following morning, females are checked for the presence of a vaginal copulation plug, a clump of coagulated proteins from the male seminal fluid. As mating usually occurs during midnight, the day of vaginal plug detection is considered to be 0.5 dpc. Although vasectomized males can be purchased from some vendors, the surgical procedure described herein is relatively easy and does not require any additional instruments than required for embryo transfer.

<table border="0" cellpadding="0" cellspacing="0" width="1234">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="29">
			<td height="29" style="height:29px;width:232px;">Ketamine</td>
			<td style="width:111px;">VEDCO</td>
			<td style="width:203px;">Ketaved ANADA 200-257</td>
			<td style="width:691px;">To be ordered by a licensed veterinarian.</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:232px;">Xylazine</td>
			<td style="width:111px;">Lloyd laboratories</td>
			<td style="width:203px;">Anased NADA #139-236</td>
			<td style="width:691px;">To be ordered by a licensed veterinarian.</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:232px;">Buprenorphine</td>
			<td style="width:111px;">Generic</td>
			<td style="width:203px;">NDC 400-42-010-01</td>
			<td style="width:691px;">To be ordered by a licensed veterinarian.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:232px;">Eye ointment</td>
			<td style="width:111px;">Novartis</td>
			<td style="width:203px;">Genteal</td>
			<td style="width:691px;"></td>
		</tr>
		<tr height="36">
			<td height="36" style="height:36px;width:232px;">Antibiotic</td>
			<td style="width:111px;">Pfizer</td>
			<td style="width:203px;">Clavamox NADA #55-101.</td>
			<td style="width:691px;">Added to drinking water (0.3 mg/ml of amoxicillin trihydrate and 0.075 mg/ml of clavulanate potassium). Add 1.5 ml of the reconstituted 15 ml bottle to 250 ml of water.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:232px;">Dressing serrated forceps</td>
			<td style="width:111px;">ROBOZ</td>
			<td style="width:203px;">RS-8120</td>
			<td style="width:691px;">Any medium size surgical-grade steel straight forceps will work.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:232px;">Micro dissecting serrated forceps</td>
			<td style="width:111px;">ROBOZ</td>
			<td style="width:203px;">RS-5137</td>
			<td style="width:691px;">These ones are curved at a 90&#186; angle. Straight forceps can be used if preferred.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:232px;">Slight curved micro dissection forceps</td>
			<td style="width:111px;">ROBOZ</td>
			<td style="width:203px;">RS-5136</td>
			<td style="width:691px;">This model is particularly useful to hold the oviduct.</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:232px;">Scissors</td>
			<td style="width:111px;">ROBOZ</td>
			<td style="width:203px;">RS-5880</td>
			<td style="width:691px;">Any regular surgical grade steel small straight scissors will work.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:232px;">27G needles</td>
			<td style="width:111px;">Beckton-Dickinson</td>
			<td style="width:203px;">305136</td>
			<td style="width:691px;">Smaller needles (30G) can be also used. 25G may be a bit too big.</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:232px;">Clip applier</td>
			<td style="width:111px;">MiKRon</td>
			<td style="width:203px;">42763</td>
			<td style="width:691px;"></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:232px;">9 mm Clips</td>
			<td style="width:111px;">MiKRon</td>
			<td style="width:203px;">427631</td>
			<td style="width:691px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:232px;">Clip remover</td>
			<td style="width:111px;">MiKRon</td>
			<td style="width:203px;">7637</td>
			<td style="width:691px;">Two pairs of teeth forceps (ROBOZ RS-8160) can be used instead.</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:232px;">Suture needle holder</td>
			<td style="width:111px;">ROBOZ</td>
			<td style="width:203px;">RS-7820</td>
			<td style="width:691px;"></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:232px;">Suture</td>
			<td style="width:111px;">Dowist Gell</td>
			<td style="width:203px;">5-0 Dexon S 7204-21</td>
			<td style="width:691px;">Can be substituted for any 4-0 to 6-0 absorbable suture with a narrow curved needle.</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:232px;">Glass capillaries</td>
			<td style="width:111px;">VWR</td>
			<td style="width:203px;">100 ul calibrated pipettes 53432-921</td>
			<td style="width:691px;">It includes a mouth aspirator system that only requires to attach a 0.22 um filter in the tubing to be ready to use. More information can be obtained in ref. 8.</td>
		</tr>
		<tr height="37">
			<td height="37" style="height:37px;width:232px;">Burner</td>
			<td style="width:111px;">KISAG AG</td>
			<td style="width:203px;">Typ 2002</td>
			<td style="width:691px;">Gas operated burner, can be charged with Kigas (CH-4512, from the same vendor). Alcohol burners may be also used, but gas provides a higher temperature and this burner provides a small and precise flame.</td>
		</tr>
		<tr height="105">
			<td height="105" style="height:105px;width:232px;">Stereomicroscope</td>
			<td style="width:111px;">Leica</td>
			<td style="width:203px;">MZFLIII</td>
			<td style="width:691px;">This is an expensive estereomicroscope with fluorescence, that can be also used for other purposes. There are cheaper options such as Leica MZ8 or Nikon SMZ-10 or SMZ-2B, to name a few. It is better to use two stereomicroscopes, one for handling the embryos (which does not need to be a very nice one) and another one for the recipient. The one used for the recipient should display a long distance from the stage plate to the objective lense, in order to be able to focus 3-4 cm above the stage plate (where the oviduct will be placed) and still leave some room for the surgeon; most of the stereomicroscopes can do this, but some cannot.&#160;</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:232px;">Fiber optics ilumination</td>
			<td style="width:111px;">Dolan Jenner</td>
			<td style="width:203px;">Fiber lite</td>
			<td style="width:691px;">To iluminate the surgical area. There are different systems available.</td>
		</tr>
		<tr height="52">
			<td height="52" style="height:52px;width:232px;">Warm stages</td>
			<td style="width:111px;">American scope</td>
			<td style="width:203px;"><a href="https://exch.mail.umd.edu/owa/redir.aspx?C=1qTJKejamUSfudeYG_MlZHvTY3dsJM9Iaqr2SnwGD4ECWGzB8e8Rpg--_L7u0vJmyatXQJzGQ0k.&amp;URL=http%3a%2f%2fstore.amscope.com%2ftcs-100.html" target="_blank">http://store.amscope.com/tcs-100.html</a></td>
			<td style="width:691px;">These can be placed over the stage plate of the stereomicroscope. Some modifications (inserting a stick to level the stage) may be needed if it is too short for the stereomicroscope. A big warm stage can be used for warming the cage if it is available. If not, a regular heating pad can be used, but temperature must be checked.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:232px;">Culture dishes for embryo manipulation</td>
			<td style="width:111px;">Falcon</td>
			<td style="width:203px;">353001</td>
			<td style="width:691px;">351008 may be also used, they made narrower drops.</td>
		</tr>
	</tbody>
</table>

utero-tubal embryo transfer and vasectomy in the mouse model

The transfer of preimplantation embryos to a surrogate female is a required step for the production of genetically modified mice or to study the effects of epigenetic alterations originated during preimplantation development on subsequent fetal development and adult health. The use of an effective and consistent embryo transfer technique is crucial to enhance the generation of genetically modified animals and to determine the effect of different treatments on implantation rates and survival to term. Embryos at the blastocyst stage are usually transferred by uterine transfer, performing a puncture in the uterine wall to introduce the embryo manipulation pipette. The orifice performed in the uterus does not close after the pipette has been withdrawn, and the embryos can outflow to the abdominal cavity due to the positive pressure of the uterus. The puncture can also produce a hemorrhage that impairs implantation, blocks the transfer pipette and may affect embryo development, especially when embryos without zona are transferred. Consequently, this technique often results in very variable and overall low embryo survival rates. Avoiding these negative effects, utero-tubal embryo transfer take advantage of the utero-tubal junction as a natural barrier that impedes embryo outflow and avoid the puncture of the uterine wall. Vasectomized males are required for obtaining pseudopregnant recipients. A technique to perform vasectomy is described as a complement to the utero-tubal embryo transfer.

Utero-tubal embryo transfer provides a mean to transfer embryos to the uterus avoiding some of the complications associated to the uterine embryo transfer2,9,10. In Table 1 we show some representative result we have obtained transferring CD1 blastocysts subjected to different kinds of manipulations to CD1 recipients following the protocol described. The survival to term (% of embryos resulting in a pup) or survival to E15 (in the case of lentivirus exposed) is similar between embryos simply cu...

Watch this Scientific Journal Video about Utero-tubal Embryo Transfer and Vasectomy in the Mouse Model at JoVE.com

Utero-tubal Embryo Transfer and Vasectomy in the Mouse Model

Utero-tubal embryo transfer uses the utero-tubal junction as a barrier to prevent the embryo outflow that may occur when performing uterine transfer. Vasectomized males are required to obtain pseudopregnant recipients for embryo transfer. Both techniques are discussed.

The transfer of preimplantation embryos to a surrogate female is a required step for the production of genetically modified mice or to study the effects ...

utero-tubal-embryo-transfer-and-vasectomy-in-the-mouse-model

Research

JoVE Journal

Biology

47.3K Views.  United States Department of Agriculture. Utero-tubal embryo transfer uses the utero-tubal junction as a barrier to prevent the embryo outflow that may occur when performing uterine transfer. Vasectomized males are required to obtain pseudopregnant recipients for embryo transfer. Both techniques are discussed.

Video: Utero-tubal Embryo Transfer and Vasectomy in the Mouse Model

Nuclear Transfer into Mouse Oocytes

Nuclear transfer into an unfertilized oocyte can restore developmental potential to a differentiated cell. This demonstrates that the processes underlying development, differentiation and aging are epigenetic rather than genetic processes. The reversibility of these processes opens exciting perspectives in basic research, and in the more distant future, in regenerative medicine. In the mouse, embryonic stem cells can be derived from cloned preimplantation stage embryos. Such embryonic stem cells have the ability to give rise to all cell types of the adult organism. Importantly, these cells are genetically identical to the donor. If applicable to human, this would allow the derivation of stem cells from a patient. These cells could then be differentiated into the affected cell type of the patient and studied in vitro, or used to replace the damaged or missing cells. The study of nuclear transfer in the mouse remains important as it can inform us about the principles of nuclear reprogramming. This movie and the accompanying protocol are intended to help learning nuclear transfer in the mouse, a method initially developed in the group of Prof. Yanagimachi (WAKAYAMA et al. 1998).

This movie and the protocol are intended to help learning nuclear transfer.

Nuclear transfer into an unfertilized oocyte can restore developmental potential to a differentiated cell. This demonstrates that the processes underlying ...

Assay for Neural Induction in the Chick Embryo

The chick embryo is a valuable tool in the study of early embryonic development. Its transparency, accessibility and ease of manipulation, make it an ideal tool for studying the formation and initial patterning of the nervous system. This video demonstrates how to graft organizer tissue into a host, a method by which Hensen s node (the organizer in the chick embryo) is grafted to a host competent ectoderm. The organizer graft instructs overlying na ve tissue to adopt a neural fate via neural inducing signals. This mechanism is referred to as neural induction, and constitutes the initial step in the formation of brain and spinal cord in amniotes. This method is essentially used for the characterization of putative neural inducing molecules in chick. This video demonstrates the different steps in the assay for neural induction; First, the donnor embryo is explanted and pinned on a dish. Then, the host embryo is prepared for New culture. The graft is excised and transplanted to the host area pellucida margin. The host is cultured for 18-22 hrs. The assembly is fixed and processed for further applications (e.g. in situ hybridization). This method was originally devised by Waddington 1,2 and Gallera 3,4.

Neural induction is the first step in the formation of the brain. It is a mechanism by which Hensen's node (organizer), instructs adjacent tissue to adopt a neural fate, i.e. to give rise to the nervous system. This video demonstrates an assay for neural induction in chick embryo.

The chick embryo is a valuable tool in the study of early embryonic development. Its transparency, accessibility and ease of manipulation, make it an ...

Electrophysiological Recording in the Drosophila Embryo

Drosophila is a premier genetic model for the study of both embryonic development and functional neuroscience. Traditionally, these fields are quite isolated from each other, with largely independent histories and scientific communities. However, the interface between these usually disparate fields is the developmental programs underlying acquisition of functional electrical signaling properties and differentiation of functional chemical synapses during the final phases of neural circuit formation. This interface is a critically important area for investigation. In Drosophila, these phases of functional development occur during a period of &lt;8 hours (at 25&deg;C) during the last third of embryogenesis. This late developmental period was long considered intractable to investigation owing to the deposition of a tough, impermeable epidermal cuticle. A breakthrough advance was the application of water-polymerizing surgical glue that can be locally applied to the cuticle to enable controlled dissection of late-stage embryos. With a dorsal longitudinal incision, the embryo can be laid flat, exposing the ventral nerve cord and body wall musculature to experimental investigation. Whole-cell patch-clamp techniques can then be employed to record from individually-identifiable neurons and somatic muscles. These recording configurations have been used to track the appearance and maturation of ionic currents and action potential propagation in both neurons and muscles. Genetic mutants affecting these electrical properties have been characterized to reveal the molecular composition of ion channels and associated signaling complexes, and to begin exploration of the molecular mechanisms of functional differentiation. A particular focus has been the assembly of synaptic connections, both in the central nervous system and periphery. The glutamatergic neuromuscular junction (NMJ) is most accessible to a combination of optical imaging and electrophysiological recording. A glass suction electrode is used to stimulate the peripheral nerve, with excitatory junction current (EJC) recordings made in the voltage-clamped muscle. This recording configuration has been used to chart the functional differentiation of the synapse, and track the appearance and maturation of presynaptic glutamate release properties. In addition, postsynaptic properties can be assayed independently via iontophoretic or pressure application of glutamate directly to the muscle surface, to measure the appearance and maturation of the glutamate receptor fields. Thus, both pre- and postsynaptic elements can be monitored separately or in combination during embryonic synaptogenesis. This system has been heavily used to isolate and characterize genetic mutants that impair embryonic synapse formation, and thus reveal the molecular mechanisms governing the specification and differentiation of synapse connections and functional synaptic signaling properties.

Electrophysiological Recording in the Drosophila Embryo

Electrophysiological recordings from Drosophila embryos allow analyses of developing muscle and neuron electrical properties, as well as characterization of functional synaptogenesis at the glutamatergic neuromuscular junction and central cholinergic and GABAergic synapses.

Drosophila is a premier genetic model for the study of both embryonic development and functional neuroscience. Traditionally, these fields are quite ...

In vivo Imaging and Therapeutic Treatments in an Orthotopic Mouse Model of Ovarian Cancer

Human cancer and response to therapy is better represented in orthotopic animal models. This paper describes the development of an orthotopic mouse model of ovarian cancer, treatment of cancer via oral delivery of drugs, and monitoring of tumor cell behavior in response to drug treatment in real time using in vivo imaging system. In this orthotopic model, ovarian tumor cells expressing luciferase are applied topically by injecting them directly into the mouse bursa where each ovary is enclosed. Upon injection of D-luciferin, a substrate of firefly luciferase, luciferase-expressing cells generate bioluminescence signals. This signal is detected by the in vivo imaging system and allows for a non-invasive means of monitoring tumor growth, distribution, and regression in individual animals. Drug administration via oral gavage allows for a maximum dosing volume of 10 mL/kg body weight to be delivered directly to the stomach and closely resembles delivery of drugs in clinical treatments. Therefore, techniques described here, development of an orthotopic mouse model of ovarian cancer, oral delivery of drugs, and in vivo imaging, are useful for better understanding of human ovarian cancer and treatment and will improve targeting this disease.

In vivo Imaging and Therapeutic Treatments in an Orthotopic Mouse Model of Ovarian Cancer

Orthotopic animal models of ovarian cancer replicate better human disease and therefore enhance our understanding of cancer progression and tumor response to therapy. A mouse model receives an intrabursal injection of luciferase-expressing ovarian tumor cells. Treatment is administered via oral gavage. Tumor growth is monitored by in vivo imaging system.

Human cancer and response to therapy is better represented in orthotopic animal models.  This paper describes the development of an orthotopic mouse model ...

Tracking Morphogenetic Tissue Deformations in the Early Chick Embryo

Embryonic epithelia undergo complex deformations (e.g. bending, twisting, folding, and stretching) to form the primitive organs of the early embryo. Tracking fiducial markers on the surfaces of these cellular sheets is a well-established method for estimating morphogenetic quantities such as growth, contraction, and shear. However, not all surface labeling techniques are readily adaptable to conventional imaging modalities and possess different advantages and limitations. Here, we describe two labeling methods and illustrate the utility of each technique. In the first method, hundreds of fluorescent labels are applied simultaneously to the embryo using magnetic iron particles. These labels are then used to quantity 2-D tissue deformations during morphogenesis. In the second method, polystyrene microspheres are used as contrast agents in non-invasive optical coherence tomography (OCT) imaging to track 3-D tissue deformations. These techniques have been successfully implemented in our lab to studythe physical mechanisms of early head fold, heart, and brain development, and should be adaptable to a wide range morphogenetic processes.

This article describes surface labeling and ex ovo tissue culture in the early chick embryo. Techniques amenable to time-lapse bright field, fluorescence, and optical coherence tomography imaging are presented. Tracking surface labels with high spatiotemporal resolution enables kinematic quantities such as morphogenetic strains (deformations) to be calculated in both two and three dimensions.

Embryonic epithelia undergo complex deformations (e.g. bending, twisting, folding, and stretching) to form the primitive organs of the early embryo. ...

Generation of Mice Derived from Induced Pluripotent Stem Cells

The production of induced pluripotent stem cells (iPSCs) from somatic cells provides a means to create valuable tools for basic research and may also produce a source of patient-matched cells for regenerative therapies. iPSCs may be generated using multiple protocols and derived from multiple cell sources. Once generated, iPSCs are tested using a variety of assays including immunostaining for pluripotency markers, generation of three germ layers in embryoid bodies and teratomas, comparisons of gene expression with embryonic stem cells (ESCs) and production of chimeric mice with or without germline contribution2. Importantly, iPSC lines that pass these tests still vary in their capacity to produce different differentiated cell types2. This has made it difficult to establish which iPSC derivation protocols, donor cell sources or selection methods are most useful for different applications.
The most stringent test of whether a stem cell line has sufficient developmental potential to generate all tissues required for survival of an organism (termed full pluripotency) is tetraploid embryo complementation (TEC)3-5. Technically, TEC involves electrofusion of two-cell embryos to generate tetraploid (4n) one-cell embryos that can be cultured in vitro to the blastocyst stage6. Diploid (2n) pluripotent stem cells (e.g. ESCs or iPSCs) are then injected into the blastocoel cavity of the tetraploid blastocyst and transferred to a recipient female for gestation (see Figure 1). The tetraploid component of the complemented embryo contributes almost exclusively to the extraembryonic tissues (placenta, yolk sac), whereas the diploid cells constitute the embryo proper, resulting in a fetus derived entirely from the injected stem cell line.
Recently, we reported the derivation of iPSC lines that reproducibly generate adult mice via TEC1. These iPSC lines give rise to viable pups with efficiencies of 5-13%, which is comparable to ESCs3,4,7 and higher than that reported for most other iPSC lines8-12. These reports show that direct reprogramming can produce fully pluripotent iPSCs that match ESCs in their developmental potential and efficiency of generating pups in TEC tests. At present, it is not clear what distinguishes between fully pluripotent iPSCs and less potent lines13-15. Nor is it clear which reprogramming methods will produce these lines with the highest efficiency. Here we describe one method that produces fully pluripotent iPSCs and "all- iPSC" mice, which may be helpful for investigators wishing to compare the pluripotency of iPSC lines or establish the equivalence of different reprogramming methods.

Generating induced pluripotent stem cell (iPSC) lines produces lines of differing developmental potential even when they pass standard tests for pluripotency. Here we describe a protocol to produce mice derived entirely from iPSCs, which defines the iPSC lines as possessing full pluripotency1.

The production of induced pluripotent stem cells (iPSCs) from somatic cells provides a means to create valuable tools for basic research and may also ...

Mouse Embryonic Development in a Serum-free Whole Embryo Culture System

Mid-gestation stage mouse embryos were cultured utilizing a serum-free culture medium prepared from commercially available stem cell media supplements in an oxygenated rolling bottle culture system. Mouse embryos at E10.5 were carefully isolated from the uterus with intact yolk sac and in a process involving precise surgical maneuver the embryos were gently exteriorized from the yolk sac while maintaining the vascular continuity of the embryo with the yolk sac. Compared to embryos prepared with intact yolk sac or with the yolk sac removed, these embryos exhibited superior survival rate and developmental progression when cultured under similar conditions. We show that these mouse embryos, when cultured in a defined medium in an atmosphere of 95% O2 / 5% CO2 in a rolling bottle culture apparatus at 37 &#176;&#8203;C for 16-40 hr, exhibit morphological growth and development comparable to the embryos developing in utero. We believe this method will be useful for investigators needing to utilize whole embryo culture to study signaling interactions important in embryonic organogenesis.

Serum utilized in embryo cultures contains unknown components that can affect the outcome of experiments especially in studies involving signaling interactions. Here we utilized a serum-free oxygenated culture system and show that mid-gestation mouse embryos cultured for 16-40 hr&#160;exhibit morphological development comparable to embryos developing in utero.

Mid-gestation stage mouse embryos were cultured utilizing a serum-free culture medium prepared from commercially available stem cell media supplements in ...

Validation of a Mouse Model to Disrupt LINC Complexes in a Cell-specific Manner

Nuclear migration and anchorage within developing and adult tissues relies heavily upon large macromolecular protein assemblies called LInkers of the Nucleoskeleton and Cytoskeleton (LINC complexes). These protein scaffolds span the nuclear envelope and connect the interior of the nucleus to components of the surrounding cytoplasmic cytoskeleton. LINC complexes consist of two evolutionary-conserved protein families, Sun proteins and Nesprins that harbor C-terminal molecular signature motifs called the SUN and KASH domains, respectively. Sun proteins are transmembrane proteins of the inner nuclear membrane whose N-terminal nucleoplasmic domain interacts with the nuclear lamina while their C-terminal SUN domains protrudes into the perinuclear space and interacts with the KASH domain of Nesprins. Canonical Nesprin isoforms have a variable sized N-terminus that projects into the cytoplasm and interacts with components of the cytoskeleton. This protocol describes the validation of a dominant-negative transgenic mouse strategy that disrupts endogenous SUN/KASH interactions in a cell-type specific manner. Our approach is based on the Cre/Lox system that bypasses many drawbacks such as perinatal lethality and cell nonautonomous phenotypes that are associated with germline models of LINC complex inactivation. For this reason, this model provides a useful tool to understand the role of LINC complexes during development and homeostasis in a wide array of tissues.

Nuclear envelope proteins play a central role in many basic biological processes and have been implicated in a variety of human diseases. This protocol describes a new Cre/Lox-based mouse model that allows for the spatiotemporal control of LINC complexes disruption.

Nuclear migration and anchorage within developing and adult tissues relies heavily upon large macromolecular protein assemblies called LInkers of the ...

Nuclei Isolation from Adult Mouse Kidney for Single-Nucleus RNA-Sequencing

The kidneys regulate diverse biological processes such as water, electrolyte, and acid-base homeostasis. Physiological functions of the kidney are executed by multiple cell types arranged in a complex architecture across the corticomedullary axis of the organ. Recent advances in single-cell transcriptomics have accelerated the understanding of cell type-specific gene expression in renal physiology and disease. However, enzyme-based tissue dissociation protocols, which are frequently utilized for single-cell RNA-sequencing (scRNA-seq), require mostly fresh (non-archived) tissue, introduce transcriptional stress responses, and favor the selection of abundant cell types of the kidney cortex resulting in an underrepresentation of cells of the medulla.
Here, we present a protocol that avoids these problems. The protocol is based on nuclei isolation at 4 &#176;C from frozen kidney tissue. Nuclei are isolated from a central piece of the mouse kidney comprised of the cortex, outer medulla, and inner medulla. This reduces the overrepresentation of cortical cells typical for whole-kidney samples for the benefit of medullary cells such that data will represent the entire corticomedullary axis at sufficient abundance. The protocol is simple, rapid, and adaptable and provides a step towards the standardization of single-nuclei transcriptomics in kidney research.

Here, we present a protocol to isolate high-quality nuclei from frozen mouse kidneys that improve the representation of medullary kidney cell types and avoids the gene expression artifacts from enzymatic tissue dissociation.

The kidneys regulate diverse biological processes such as water, electrolyte, and acid-base homeostasis. Physiological functions of the kidney are ...

Cervical Manipulation Induced Pseudopregnancy in Mice for Assisted Reproduction

Inducing Pseudopregnancy in Female Mice Without the Need for Vasectomized Males Prior to Non-Surgical Embryo Transfer or Artificial Insemination

For successfully maintaining pregnancy with embryo transfer or artificial insemination,&#160;female recipient mice must be induced into a pseudopregnant state. Female mice are traditionally paired overnight with vasectomized males, and the following morning, the presence of a copulation plug is assessed. To increase the efficiency of producing pseudopregnant females, a cervical manipulation technique has been standardized to be used in combination with non-surgical embryo transfer or artificial insemination techniques in mice. The blunt end of a small plastic rod is inserted vaginally to contact the cervix and is vibrated for 30 s by contact with a trimmer. The procedure is quick and does not require anesthesia or analgesia. This technique increases the reliability and predictability of producing pseudopregnant females and entirely eliminates the requirement for vasectomized males. For CD1 mice, the efficiency of pseudopregnancy induction using cervical manipulation was 83% for females in estrus (N = 76) but only 38% of females in estrus were plugged by vasectomized males (N = 24). Artificial insemination in CD1 mice was performed by estrus synchronization with hormones, cervical manipulation, and the uterine transfer of sperm. Artificial insemination recipients receiving cervical manipulation (N = 76) had a pregnancy rate of 72% and an average litter size of 8.3 pups. This method can also be used to produce pseudopregnant females for non-surgical embryo transfer. Therefore, inducing pseudopregnancy by cervical manipulation is a convenient and efficient alternative to mating with a vasectomized male when performing non-surgical assisted reproduction techniques. Using cervical manipulation provides 3Rs (replacement, reduction, and refinement) benefits for assisted reproduction techniques by reducing the number of animals required and eliminating the necessity for surgically altered males.

Author Spotlight: Inducing Pseudopregnancy in Female Mice Without the Need for Vasectomized Males Prior to Non-Surgical Embryo Transfer or Artificial Insemination  

The cervical manipulation method presented can induce pseudopregnancy in mice without the need for breeding females with vasectomized males. The induction of pseudopregnancy is required for the success of non-surgical embryo transfer and non-surgical artificial insemination, both of which are also presented.

For successfully maintaining pregnancy with embryo transfer or artificial insemination,&#160;female recipient mice must be induced into a pseudopregnant ...

Methods Article

Utero-tubal Embryo Transfer and Vasectomy in the Mouse Model