Mouse Embryos

JAX provides cryopreserved mouse embryos from inbred and genetically modified mice to facilitate strain importation and microinjection experiments.

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Key benefits

  • Many JAX® Mice strains available as embryos
  • Eliminates quarantine or rederivation requirements
  • Avoids restrictions associated with shipping or importing live mice


  • Enough embryos are provided to recover at least two pairs of mice, with one mouse of each pair being a carrier.
  • Detailed recovery protocols are provided.

Find Cryopreserved Embryos

To check if your strain of interest is available as frozen embryo:

Embryo shipping, receiving and embryo transfer - frequently asked questions


Are there books that may help me learn embryo transfer?

Yes. We recommend Manipulating the Mouse Embryo, available from Cold Spring Harbor Laboratory Press.

Where I could receive training for thawing straws and transferring embryos?

We highly recommend that you attend the Embryo Handling Workshop, where you will learn how to thaw and transfer embryos. You also will receive additional support when you return to your lab. The workshops are held in May and September at The Jackson Laboratory. See our list of current courses for more details.

How will attending the Embryo Handling Workshop help me?

We will teach you how to collect, thaw and transfer embryos, and we will give you additional help and support when you return to your lab. See our Courses and Conferences website for details on upcoming Embryo Handling Workshops.

Would someone from The Jackson Laboratory talk me through the embryo transfer procedure on the phone?

No. If you need help with transferring embryos, we strongly recommend that you take the Embryo Handling Workshop. See our Courses and Conferences website for details.


Can I use the shipper to store my embryos until I am ready to transfer my embryos?

No. The dry shipper is for transport only. Embryos should be transferred to a permanent storage container immediately.

Do I need a liquid nitrogen supply at my facility?

Yes. You will need to transfer samples to a permanent storage container.

We have received a shipper to send our embryos to The Jackson Laboratory. Do we have to fill it with Liquid Nitrogen before sending it?

No. The shipper is pre-charged with liquid nitrogen. Simply put your embryos in the shipper and make sure the embryo information is attached to it.

How do I know the dry shipper has not been opened or tampered with in transit?

The plastic wire ties on the outside and inside catches of the container should still be in place when the shipper arrives.

How long can the samples be exposed to air when moving them to a storage vessel from the dry shipper?

No more than 5 seconds for straws and 30 seconds for vials.

I received a shipper with my samples enclosed, but where is the information about what I received?

An envelope in the lid of the dry shipper contains all the information you need. If it is missing, please email

There is no liquid nitrogen in the shipping container. Will my samples still be ok?

The shipping container is a "dry shipper." The liquid nitrogen is in the walls. Your samples are safe but should be moved to a permanent storage container immediately.

What do I do with the dry shipper when my samples have been removed?

After your samples have been stored, please ship the dry shipper back within 72 hours to the following address:

The Jackson Laboratory
Importation B64
600 Main Street
Bar Harbor, ME 04609

Please secure the lid and outside latch using the included zip tie to secure the latch. Do not wrap or box the dry shipper for the return shipment. Please call 1-800-422-6423 (5 AM to 5 PM PT) if you have any questions.


Can I culture my embryos before transferring them into the uterus?

We don't recommend it. Transfer them immediately after they thaw.

Can I get practice embryos from The Jackson Laboratory before I order important strains?

Yes. We can supply practice embryos on request. Email

Do you guarantee that we will recover mice from your frozen embryos?

No. We guarantee that we have successfully recovered all the strains available for sale, but we cannot guarantee that you will have similar results.

How long can I wait between thawing embryos and transferring them?

Transfer two-cell embryos within an hour of thawing them. You can thaw eight-cell embryos and keep them in a refrigerator for 3-4 hours before you transfer them.

Is timing critical when thawing embryos?

Yes. You should follow the protocol carefully.

Should I transfer all the embryos I recover?

If you are not experienced in grading embryos, you should transfer all of them -- even the ones that are not perfect.

Should I transfer embryos to a 0.5- or a 2.5-day pseudopregnant female?

Transfer 2-, 4-, and 8-cell embryos to a 0.5-day pseudopregnant female. A 2.5-day pseudopregnant female is used for transferring blastocysts.

Should my facility have a pseudo colony?

Ideally, yes, but you can vasectomize males and start your own.

If I do not recover any live mice from the practice straws, should I request more practice straws?

Yes. Please do not thaw out any strains received until you have successfully recovered the practice embryos. Email

What strain do you use for pseudopregnant females?

Many hybrids and outbreds can be used successfully to make pseudopregnant female mice. We use CByB6F1/J (Stock number:100009) animals.

What media do I need to thaw embryos?

You will need PBS for thawing vials and M2 for thawing straws. 

Recovery thaw protocol for straws

Reviewed 6/23/2004

Supplies for thaw

  • Liquid nitrogen Dewar
  • 25 degrees Celsius water bath
  • Scissor
  • Kim Wipe
  • Metal plunger (enclosed)
  • Timer
  • Forceps
  • Pipetter
  • 10 - 35mm Falcon dishes containing 1 ml of M2
  • M2 - See enclosed media sheet

Thaw protocol

The procedure used for freezing and thawing in The Jackson Laboratory Frozen Embryo Repository is based on that described by Renard, J.P. and Babinet, C. (1984). High survival of mouse embryos after rapid freezing and thawing inside plastic straw with 1-2 propanediol as cryoprotectant. Journal of Experimental Zoology 230, 443-448

  • Transfer the straw from the liquid nitrogen storage freezer to a smaller container of liquid nitrogen as quickly as possible.

  • Using forceps, hold the straw near the label and hold in air for 40 seconds.

  • Place straw, label end up in to the room temperature water bath (25 degrees Celsius) until the ice disappears (~5 - 10 seconds).

  • Carefully wipe the straw dry with a Kim Wipe.

  • Holding the straw firmly on the embryo side of the PVA plug (yellowish color) cut through the middle of the PVA plug.

  • Holding the straw near the bottom seal, cut off the seal.

  • Using your index finger and thumb, round off the end of the straw near the embryos.

  • Using the plunger, expel the entire liquid contents of the straw as one drop into a 35mm Falcon dish. Do not let the plug drop into the dish.

  • Wait 5 minutes. The embryos will shrink considerably.

  • Transfer the embryos to 1ml of M2. They will rapidly take up water and assume normal appearance.

  • Wash the embryos through 10 dishes of M2, using a new pipette for each wash (each dish should contain 1ml of media).

  • Your embryos should be transferred into your clean unit as soon as possible.

    Recovery thaw protocol for vials

    Reviewed 6/23/2004

    Supplies for thaw

    • Dewar containing the sample to thaw
    • Vial rack
    • 1ml pipetter
    • Forceps
    • 10 - 35mm Falcon dishes containing 1 ml of DPBS
    • Media

    Thaw protocol

    The procedure used for freezing and thawing in The Jackson Laboratory Frozen Embryo Repository is based on that described by Whittingham, et al. [Whittingham, D., S. Leibo, et al. (1972). Survival of mouse embryos frozen to -196°C and -269°C. Science. 178:411-14.]

    Embryos require a slow thaw:

    1. To thaw, remove vials from liquid nitrogen and place in a rack at room temperature until completely thawed (this will take about 15-20 minutes).
    2. SLOWLY pipette 800ul of DPBS, drop wise into each vial to dilute the DMSO.
    3. Using a 1ml pipetter set at 1ml, suck up about half the solution and then expel slightly (to dislodge any embryos that may be stuck to the side of the vial) and then continue removing all the solution and placing it into a small petri dish.
    4. Wash the embryos through 10 dishes of DPBS, using a new pipette for each wash (each dish should contain 1ml of media). 
    5. Your embryos should be transferred into your clean unit as soon as possible.

    Cryopreservation media preparation

    Phosphate buffered saline (modified Dulbecco's)

    1. For a final volume of 100 ml of solution weigh out the following into approximately 75 ml of culture grade water:


    800.0 mg











    Sodium pyruvate


    Penicillin G


    Streptomycin sulfate


    1. Dissolve 10.0 mg CaCl2 (anhydrous) in about 10 to 20 ml of culture grade water.
    2. Add the dissolved CaCl2 to the above ingredients and bring the total volume up to 100 ml.
    3. Use 20 ml of the above solution for making up a 2 M solution of DMSO (Aldrich).
    4. Add 240.0 mg of crystallized Bovine Serum Albumin (BSA) and 0.1 ml of a 1% solution of Phenol red to the remaining 80 ml.
    5. Sterilize the solutions by filtration.


    Add each chemical in order and mix carefully.

    Gas for 5 minutes with 5% CO2, 5% O2 balanced with N2, using a 1 ml pipette submerged in the media before adding BSA. Add BSA after gassing and then incubate to dissolve. Filter with .22um filter and gas before refrigerating.

        1000 ml 200 ml


    (FW 58.44, Sigma S-5886)




    (FW 74.55,Sigma P-5405)



    MgSO4 7H20

    (FW 246.5, Sigma M-1880)




    (FW136.09, Sigma P5655)



    CaCl2 2H2O

    (FW 147, Sigma C-7902



    (add directly)





    (FW 84.01, Sigma S-5761)




    (FW180.16, Sigma G-6152)




    (FW110.0, Sigma P-4562)




    (FW 112.1, Sigma L-1375)

    3.42 ml

    0.683 ml


    (FW 372.5, Sigma P-7794)




    (FW1457.4, Sigma S-9137)



    Phenolred (1%)

    (Sigma P-0290)




    (Equitech-Bio BAC62-0050



    Always gas the medium after every use.

    Reference: Quinn P, Kerin JF and Warnes GM (1985) Improved pregnancy rate in human in vitro fertilization with the use of a medium based on the composition of human tubal fluid. Fertility and Sterility 44: 493-498.

    KSOM medium

    1. For a final volume of 100 ml of medium weigh out the following into approximately 75 ml of double distilled water:

    EDTA, disodium salt (ADD FIRST)

    (FW 372.2, Sigma)

    0.38 mg


    (FW 58.44, Fisher)

    559.5 mg



    18.5 mg


    (FW 136.09, Sigma)

    4.75 mg



    4.95 mg

    DL-Lactic Acid, sodium salt

    (MW 112.1, Sigma L-1375)

    0.174 ml


    (FW 180.16, Sigma G-6152)

    3.60 mg


    (FW84.01, Sigma)

    210.0 mg


    (MW 146.1, Sigma G-5763)

    14.5 mg

    Pyruvic Acid, sodium salt

    (FW 110.0, Sigma P-4562)

    2.2 mg

    Penicillin G

    (FW 372.5, Sigma P-7794)

    6.3 mg

    Streptomycin Sulfate

    (FW1457.4, Sigma S-9137)

    5.0 mg

    MEM Essential Amino Acids

    (GibcoBRL 11130-051)-10 ?l/ml

    1.0 ml

    MEM Non-essential AA

    (Sigma M-7145)-5 ?l/ml

    0.5 ml

    1. Dissolve 25 mg CaCl2 (anhydrous) in about 25 ml of double distilled water.
    2. Add the dissolved CaCl2 to the above ingredients and bring the total volume up to 100 ml.
    3. Add 0.1 ml of a 1% solution of Phenol red to the solution.
    4. Gas the solution using a pipette immersed in the solution with 5% CO2, 5% O2, Balance N2, for 10 minutes (should be a salmon color).
    5. Add 100 mg of crystallized Bovine Serum Albumin (BSA).
    6. Sterilize the solution by filtration, and gas before storage (do not immerse the pipette).


    Lawitts, J.A. Biggers, J.D. (1991). Optimization of mouse embryo culture media using simplex methods. J Reprod Fert 91:543-556.

    Lawitts, J.A. Biggers, J.D. (1992). Joint effects of sodium chloride, glutamine, and glucose in mouse preimplantation embryo culture media. Mol Reprod Dev 31:189-194.

    Lawitts, J.A. Biggers, J.D. Culture of preimplantation embryos. In Methods in Enzymology: Guide to Techniques in Mouse Development. P.M. Wasserman and M.L. DePomphilis (eds.) 225:153-164. Academic Press. 1993

    Erbach, G.T. Lawitts, J.A. Papaioannou, V.E. Biggers, J.D. (1994).Differential growth of the mouse preimplantation embryo in chemically defined media. Biol. Reprod. 50:1027-1033.

    M2 media preparation

    M2 medium is conveniently made from stock solutions.

    M2 stock solutions

    Stock A 10X concentration (expires in 3 months)
    Stock B 10X concentration (expires in 2 weeks)
    Stock C 100X concentration (expires in 2 weeks)
    Stock D100X concentration (expires in 3 months)
    Stock E 100X concentration (expires in 3 months)

    Preparing M2 stock solutions:

    Prepare stocks A, B, C, and D

    1. Zero scale with the beaker on it.
    2. Add approximately one half of the distilled water necessary for the stock solution.
    3. Add the proper amounts of each component stirring occasionally.
    4. Add distilled water until scale reads desired grams. (example: Stock A = 200 g, Stock B = 20 g)
    5. Filter through a 150 or 250 ml filter system depending on the amount of stock solution made.

    Prepare stock E

    1. Repeat steps 1-3 from above.
    2. Adjust the pH to 7.4 with 0.2 N NaOH.
    3. Add distilled water until scale reads desired grams.
    4. Filter through a 250ml Filter System.

    Preparing M2 from stock solutions

    1. Zero scale with the beaker on it.
    2. Add the proper amount of each stock solution starting with Stock A and ending at the distilled water. Scale will read 200 g.
    3. Add 0.8 grams of Bovine Albumin and let sit until dissolved.
    4. Adjust pH to 7.2 – 7.4 if necessary, using 0.2 N NaOH.
    5. Filter sterilize with a 22 um filter
    6. Measure the osmolality of the medium. It will range between 265 and 280.


    per 200 ml

    Stock A(x10), 20 ml

    B(x10), 3.2 ml

    C(x100), 2 ml

    D(x100), 2 ml

    E(x10), 16.8

    Distilled H2O, 156 ml

    BSA, 0.8 g

    *Store stock solutions and M2 in the refrigerator at 4 degrees C.

    1 Molar sucrose in M2

    Used as an osmotic buffer for embryo cryopreservation.

    1. Measure 10ml of M2.
    2. Add 3.42 g of sucrose.
    3. Mix by gently rock media until sucrose is completely dissolved.

    Sucrose Sigma Cat. # S-1888

    Miscelaneous supplies & equipment

    Component Sigma cat. # Size ordered g/200 mL

















    soduim lactate










    10,000,000 u






    Component     g/20 mL





    Phenol red





    g/10 mL

    sodium pyruvate





    g/50 mL






    g/250 mL





    Phenol red


    Albumin, bovine





     Fisher Cat.#

    150 ml filter system

    SCGP U01 RE

    12 pack

    .22 micrometers

    250 ml filter system

    SCGP U02 RE

    12 pack

    .22 micrometers


    Propylene glycol

    1. Measure 8.8 ml of M2.
    2. Add 1.2 ml of 1,2-Propanediol.
      1. 1,2-Propanediol has a high viscosity.
      2. Make sure that all excess Propanediol is removed from the outside of the pipette.
      3. After adding the initial amount of Propanediol, allow it to collect at the end of pipette before expelling the remaining Propanediol into the solution.
    3. Mix by gently rocking media.
    Component Sigma cat. #



    Store at 4°C, discard after 1 week.

    MEM medium

    1. For a final volume of 200 ml of medium, measure out the following into 174 ml double distilled water:

    10X EBSS (see below)

    20 ml

    E. Amino Acid 50X

    4 ml

    100X Vitamins

    2 ml

    Na Pyruvate

    5 mg

    K Penn

    15 mg


    10 mg


    58.4 mg


    0.44 g


    0.76 mg

    1. Add 0.2 ml of 1% Phenol red solution.
    2. Gas for ten minutes with 5% CO2, 5% O2, balance N2, using a pipette immersed in the solution.
    3. Add 600 mg crystallized Bovine Serum Albumin (BSA), and allow to dissolve.
    4. 5. Sterilize by filtration, and re-gas before storage.

    10X EBSS

    200 ml

    CaCl2 2 H2O

    (Sigma C-7902)

    0.53 g



    0.80 g

    MgSO4 7 H2O


    0.40 g



    13.60 g


    (Sigma S-5011)

    0.25 g


    (Sigma G-6152)

    2.0 g

    Calcium dihydrate should be dissolved first in a separate container with millipore H2O .

    **Add the CaCl2 last after all the other chemicals have dissolved.



    2, 2, 2 Tribromoethanol
    Tertiary amyl alcohol

    Stock solution:

    25 g Tribromoethanol in 15.5 ml amyl alcohol.
    Store in dark (wrap bottle in foil).

    Solution for injection:

    1 ml of stock solution to 50 ml of isotonic saline.
    Warm to 40ºC, shake well, then store in refrigerator.


    0.015 ml per gram body weight or 0.4 ml per average adult mouse.

    Sperm cryoprotectant

    (D+) raffinose pentahydrate (Sigma R-0250)


    Skim Milk Dehydrated (Difco* 0032-17-3)


    Culture grade water


    *(Difco has been bought by Becton-Dickinson)

    Here are two recipes for making the cryoprotectant (CPA). They differ in how clear the solution will be before filtering; we can detect no difference in function.

    Version 1

    1. Warm to dissolve the raffinose completely and then dissolve the dehydrated skim milk.
    2. Centrifuge at 13,000 x g for 15 minutes
    3. Filter the supernatant through a 0.22 micron pore size filter.
    4. Aliquot and store frozen.

    Version 2

    1. Dissolve 18 g dry milk in ultrapure water with a final volume of 300 ml. Dissolve well. The final concentration will be 6%.
    2. Centrifuge 1 hour, 12,000 rpm (18,500 x g), 4 deg C.
    3. Carefully decant supernatant so that none of the pellet is taken. Using a pipette is a good way to do this. Pouring off the supernatant is not a good method (unless you have very steady hands) because the pellet is not packed very tightly.
    4. Take exactly 200 ml of the supernatant. Add 125 ml water and 72 g raffinose. Add water to 400 ml. Stir at room temperature until the raffinose to dissolves.
    5. Filter through a 0.2 micron filter. (If you've been sloppy about your decanting step, you might need to pre-filter through a 0.45 micron filter to prevent clogging at this step.)
    6. Aliquot using sterile technique and freeze.


    1. The second recipe makes a clearer CPA because centrifuging in the absence of raffinose allows the milk solids to pellet through a much less dense solution. In other words, the first recipe is essentially a density centrifugation.
    2. You can make the CPA even clearer by centrifuging longer and/or at higher speeds.
    3. Filtering the CPA is easier with a luer-type cartridge that fits on the end of a syringe than with a vacuum unit, because you can generate higher pressures. However, the second recipe results in a CPA that is clear enough to use with a vacuum unit.
    4. Remember that CPA is essentially milk and sugar and as such will be a good medium for any bacterial contaminants that you might introduce. Discard any unused solution.

    Reference: Nakagata, N. (1996). Use of cryopreservation techniques of embryos and spermatozoa for production of transgenic (Tg) mice and for maintenance of Tg mouse lines. Lab-Anim-Sci 46(2): 236-8.


    PMSG (pregnant mare serum gonadotropin) is available from:

    Sigma Chemical Company
    P.O. Box 14508
    St. Louis, MO 63178

    It is available in 10,000 I.U. vials Cat. #G-4877. Working solutions are made up by adding 400 ml of isotonic saline to a 10,000 I.U. vial of powdered hormone, which is then stirred with a magnetic stirrer for 5-6 minutes. This solution can then be packaged into 12 x 75 mm disposable plastic tubes with caps (we use BIORAD tubes as these are available in colors for coding purposes - PMS and HCG can be kept in different color tubes to avoid mix up) and frozen until needed. Frozen preparations are not kept for longer than three months.

    HCG (human chorionic gonadotropin) is also available from Sigma

    Sigma Chemical Company
    P.O. Box 14508
    St. Louis, MO 63178

    It is also available in 10,000 I.U. vials Cat. #CG-10. It is diluted in the same way as PMS described above.

    For a working solution inject the 10 ml of diluent supplied into the vial of powdered hormone (10,000 I.U.) with a syringe and needle, withdraw the mixed solution and add to 390 ml of isotonic saline. This solution can then be packaged into 12 x 75 mm disposable plastic tubes with caps as for the PMS, but in different color tubes if possible.

    These dilutions will yield 2.5 I.U. of hormone per 0.1 ml.

    JAX® Mice embryos distributed subject to General Terms and Conditions

    JAX® Mice, Product & Services
    Conditions of Use

    "MICE" means mouse strains, their progeny derived by inbreeding or crossbreeding, unmodified derivatives from mouse strains or their progeny supplied by The Jackson Laboratory ("JACKSON"). "PRODUCT(S)" means biological materials supplied by JACKSON, and their derivatives. "SERVICES" means projects conducted by JACKSON for other parties that may include but are not limited to the use of MICE or PRODUCTS. "RECIPIENT" means each recipient of MICE, PRODUCTS, or SERVICES provided by JACKSON including each institution, its employees and other researchers under its control. MICE or PRODUCTS shall not be: (i) used for any purpose other than the internal research, (ii) sold or otherwise provided to any third party for any use, or (iii) provided to any agent or other third party to provide breeding or other services. Acceptance of MICE, PRODUCTS or SERVICES from JACKSON shall be deemed as agreement by RECIPIENT to these conditions, and departure from these conditions requires JACKSON’s prior written authorization.

    No warranty


    Credit for PRODUCTS or SERVICES

    In case of dissatisfaction for a valid reason and claimed in writing by a purchaser within ninety (90) days of receipt of, PRODUCTS or SERVICES, JACKSON will, at its option, provide credit or replacement for the PRODUCT received or the SERVICES provided; JACKSON makes no other representations, and this shall be the exclusive remedy of the purchaser. Please note specific policy for live mice.

    No liability

    In no event shall JACKSON, its trustees, directors, officers, employees, and affiliates be liable for any causes of action or damages, including any direct, indirect, special, or consequential damages, arising out of the provision of MICE, PRODUCTS, or SERVICES, including economic damage or injury to property and lost profits, and including any damage arising from acts or negligence on the part of JACKSON, its agents or employees. Unless prohibited by law, in purchasing or receiving MICE, PRODUCTS, or SERVICES from JACKSON, purchaser or recipient, or any party claiming by or through them, expressly releases and discharges JACKSON from all such causes of action or damages, and further agrees to defend and indemnify JACKSON from any costs or damages arising out of any third party claims.

    MICE, PRODUCTS or SERVICES are to be used in a safe manner and in accordance with all applicable governmental rules and regulations.

    The foregoing represents the General Terms and Conditions applicable to JACKSON’s MICE, PRODUCTS or SERVICES. In addition, special terms and conditions of sale of certain MICE, PRODUCTS, or SERVICES may be set forth separately in JACKSON web pages, catalogs, price lists, contracts, and/or other documents, and these special terms and conditions shall also govern the sale of these MICE, PRODUCTS and SERVICES by JACKSON, and by its licensees and distributors.

    Acceptance of delivery of MICE, PRODUCTS or SERVICES shall be deemed agreement to these terms and conditions. No purchase order or other document transmitted by purchaser or recipient that may modify the terms and conditions hereof, shall be in any way binding on JACKSON, and instead the terms and conditions set forth herein, including any special terms and conditions set forth separately, shall govern the sale of MICE, PRODUCTS or SERVICES by JACKSON.

    Last Modified: July 17, 2014