In the course of a study on the effects of mating on plasma lh concentrations in the rat, a serendipitous finding was that plasma samples collected from male rats shortly after copulation often showed obvious evidence of haemolysis. These observations prompted a more detailed investigation. Adult Wistar rats were maintained under reversed lighting (lights on from 21.00 to 11.00 hours). Mating t...

The evolution of placentas in poeciliid fishes is associated with conception of overlapping litters and male mating strategies becoming more coercive. Sperm competition in ovaries of multiply-inseminated females may favor fertilization of immature eggs during ongoing pregnancies.

Male secondary sexual traits of animals are richly diversified in form and complexity, yet there are many species in which their precise function remains unknown. Within the genus Drosophila, species belonging to the melanogaster and obscura species groups have evolved a remarkable variety of sex combs, male-limited secondary sexual traits located on the tarsi of both front legs. Information co...

The ability of dopamine (DA) receptor antagonists to disrupt anticipatory and consummatory measures of sexual behavior displayed by male rats in bilevel chambers was investigated. In Experiment 1, systemic administration of haloperidol, pimozide, and the D1 antagonist SCH 23390 reduced the number of anticipatory level changes (LC) displayed during a 5-min period before the introduction of a sex...