Induction of fertility and pregnancy in the anœstrous ferret

Abstract

Twelve [female] ferrets were put on evening illumination Oct. 12. One came into estrus in Nov., 8 in Dec., and 2 in Jan. One failed to show vulval development even after 5 mos. Four [male][male] were put on light at the same time. Two of these were left-castrated on Nov. 28, after 47 days on light. Immediately afterwards they were given 10 rabbit units of urine of pregnancy extract for 6 days and then killed. The left testes contained no later stages of spermatogenesis than spermatids, but the right testes, under the influence of the U. P. extract, had just begun to produce spermatozoa, of which a few were found in the epididymis. A 3rd light-treated [male] was given 10 units U. P. extract from Dec. 18-27, at the end of which time it was fully functional and was producing masses of spermatozoa. On Dec. 29 and Jan. 1 it mated with light-treated [female][female]. The 4th light-treated [male] was killed on Jan. 1 after 81 days'' light, and was found to be producing large numbers of spermatozoa. It is concluded that prolonged light-treatment will activate the quiescent [male] ferret, but that the later stages of the process can be accelerated by administration of U. P. extract. The latter by itself has no stimulating effect on the quiescent testis. The 2 [female][female] mated with the fertile [male] on Dec. 29 and Jan. 1 had normal pregnancies and litters of 9 and 10 respectively on Feb. 8 and 11. Expts. on pseudopregnant light-treated [female][female] showed that the post-ovulation changes take place normally even if the evening light is discontinued after ovulation.