Abstract
Summary
Variable numbers of fertilized healthy ova (3 to 20) were transferred into 49 recipient rabbits of a synchronous stage of pseudopregnancy. The recipients were laparotomized at 8 days post coitum (p.c.) to record number and diameter of implantation sites. At 15 days p.c., the recipients were killed and number of viable embryos recorded. In 3 groups of recipients the number of implantations at 8 days p.c. was 3.3, 7.6 and 12.3 and rate of embryonic survival was 56%, 74% and 76% respectively with no significant difference between the groups. Embryonic survival tended to be positively related to number of implantations. Nonviable implantations were not located at specific sites along the uterine horn. Diameter of implantation swellings was not related to number of implantations per recipient. In 75 to 83% of the cases, the degenerating embryos (15 days p.c.) had implantation diameters (8 days p.c.) less than the average of viable implantation swellings.
Thanks are due to Ayerst Laboratories for donation of pregnant mare serum Equinex, Abbott Laboratories for Vetrophin, Fort Dodge Laboratories for Gonamone, and Upjohn Co. for Gonadogen. Thanks are also due to R. E. Mauer for technical assistance.
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