Abstract
Frog pituitaries, human chorionic gonadotropin (HCG), luteinizing hormone (LH), follicle stimulating hormone (FSH) and gonadotropinreleasing hormone (LH/FSHโRH) were tested to determine their effectiveness in eliciting the spermiation response in laboratoryโreared male bullfrogs (Rana catesbeiana). LH/FSHโRH gave the highest percentage of positive responses and the most rapid responses. Sperm acquired by cloacal sampling after LH/FSHโRH injections were fertile.
Day length (14L:10D; 8L:16D, 25ยฐ) had no measurable effect on reproductive condition, growth or sensitivity to injections of LH/FSHโRH. Spermiation response to LH/FSHโRH was depressed at low temperatures (15ยฐ, 20ยฐ C) and testicular recrudescence appeared to be inhibited at warm temperature (30ยฐC). Optimum spermiation responses were obtained at 25ยฐC.
A marked daily rhythm (unimodal) of spermiation response to LH/FSHโRH was observable. Injections given one hour before the onset and offset of a 12L:12D photoperiod (25ยฐC) were respectively the most and least effective in stimulating spermiation. The peak and trough of the rhythm were attributed to changes in pituitary sensitivity to LH/FSHโRH and not changes in testicular sensitivity to LH.
Age and size of bullfrogs utilized in these tests had no effect on spermiation response.