Reciprocal fertilization between the ferret and short‐tailed weasel with special reference to the development of ferret eggs fertilized by weasel sperm

Abstract

AbstractEpididymal spermatozoa of short‐tailed weasels (Mustela erminea) were inseminated into the uterine horns of ferrets (M. furd) and vice versa. When examined 46 hours to six days after injection of HCG for the induction of ovulation, 67 of 86 ferret eggs (78 %) were fertilized by weasel spermatozoa as shown by the enlargement of sperm head, formation of pronuclei, and the cleavage of eggs. The number of chromosomes in a few mitotic plates of cleaving eggs was much smaller than the diploid number of both the ferret and weasel. Implantation of ferret eggs fertilized by weasel spermatozoa occurred on days 13–14, similar to the ferret but different from the long delayed implantation in the weasel. On days 24–28 only seven of 39 implantation sites (18%) from six ferrets contained hybrid fetuses of varying sizes, which were much smaller than ferret fetuses. A nearly full‐grown hybrid fetus was obtained on day 42 from one of three ferrets, but no young was born from another three animals kept to day 54. Weasel eggs could be fertilized by ferret spermatozoa but their developmental potential was not determined.