CryopreservationThe purpose of embryo and/or sperm freezing is to protect against the loss of valuable, unique mouse stocks through breeding failure or disease, and to eliminate the cost of maintaining mouse lines not actively in use.In order to guarantee the availability of animal models we offer the service of harvesting embryos and/or sperm for cryopreservation.i. Embryo cryopreservationService Description:Our basic cryopreservation procedure is to obtain 8-10 stud males that carry the desired modification from the investigator. For each freezing session, we generally order wild-type female(s) of the appropriate background strain for superovulation and mating with the stud males. If the males are heterozygous for the genetic modification, it takes an average of 4 sessions to freeze enough embryos to guarantee recovery. We freeze embryos at the 4 to 8-cell stage in aliquots appropriate for recovery of the line. A test thaw is performed for each freezing session to ensure the viability of the frozen embryos. Sessions are repeated until a minimum of 300 heterozygous embryos are banked. If homozygous studs are used, then the goal is to bank 150 embryos. Frozen embryos are maintained in liquid nitrogen storage tanks.Service includes:
Responsibility of the Investigator
Personnel Training / Support (upon request)
Quality controlThe quality of each freezing session is judged by the ability of embryos from a test thaw to form blastocysts in culture.GuaranteesOur quality control procedures are designed to ensure that the banked embryos are viable. The number of embryos required to guarantee revival of the line was adopted from the standard set by commercial providers. The Center will store the embryos in liquid nitrogen tanks until shipment to the investigator. Occasionally a line cannot be frozen back effectively. Factors that contribute to this outcome are poor quality stud males and genetic background and/or genetic changes that reduce sperm count or efficiency of superovulation. If the first two freezing sessions indicate that there may be difficulty cryopreserving a line, the Center will meet with the investigator to determine the best course of action.ii. Sperm cryopreservationService Description:At this time, the only strains that can be frozen down effectively through sperm cryopreservation are strains on a hybrid background. We cannot guarantee the efficiency of in vitro fertilization, as this varies between sperm samples. In addition, we do not have this service currently available for inbred strains. For this reason we only recommend using sperm cryopreservation with lines on a hybrid background (i.e. B6/C3 F1).Service includes:
Quality controlWe will thaw one aliquot of the frozen sperm and check for motility and viability of the frozen sperm.GuaranteesThere are many factors that can affect the ability to effectively cryopreserve a line using sperm cryopreservation. Factors that contribute to this are poor quality stud males and genetic background and/or genetic changes that reduce sperm count. There is however no guarantee that the cryopreserved sperm will effectively fertilize oocytes through in vitro fertilization. The only way to check is by rederivation through in vitro fertilization. This is not included in the price since this is a very labor intensive and expensive service. However, it is recommended to assure that the line has been successfully cryopreserved.