Fertility and Development of Newt Eggs Obtained after Anterior Lobe Implants

Abstract

Five pairs of adult Newts of the species Triturus viridescens, Woods Hole strain, were transferred on January 6, 1932, from the water in which they were received at 5°C. to aquaria at 20°C. Courtship by the males followed and at least one spermatophore was deposited on the sand in each of 2 aquaria; the females, however, were not incited to follow far and the uncollected sperm cell masses were scattered by the movements of the animals. No egg-laying occurred. After a week, the males were removed from the aquaria and the females were given daily implants of anterior lobe of amphibian pituitary to stimulate ovulation (Wolf 1 ). Anterior lobes obtained from Newts of the same species, from T. dorsalis, and from the frog, Rana pipiens, were placed intramuscularly as in the work of Adams, 2 one lobe being used for each implant. Only non-fertile eggs were deposited; egg-laying ceased when implants were stopped. Untreated isolated males deposited no spermatophores.

Males of Triturus were stimulated to deposit whole spermatophores or small clusters of sperm cells (not always mature and active) by 3 methods: (1) isolated males after 2 and after 3 daily implants of amphibian anterior lobe; (2) isolated males after 4 and after 6 daily injections intraperitoneally of gonadotropic hormone as extracted from human pregnant urine; (3) males paired in aquaria with females, when the preliminary period of courtship was shortened if either had received implants. After the sperm cell masses were gathered from the bottom of the aquaria by a small glass pipette and were transferred to the cloacas of 4 treated females (with 5, 5, 6, and 2 daily implants), they laid fertile eggs. Three of the females began to deposit eggs within a day, the fourth after an interval of 8 days during which 2 more implants were given; fertility after this delay would seem to indicate that some of the spermatozoa inserted had made their way to the spermatheca. The low degree of fertility obtained by this method (142 of 365 eggs from the 4 females), in addition to the lack of fertility without pipette transfer of sperm, suggests that no spermatozoa had been collected during the fall mating season and that the few present to fertilize the eggs were those retained from the laboratory procedure.