________________________________________________________________________________ Abstract Male broiler breeders were photostimulated at different ages (56, 77, 98, 119, 147 and 161 d) during the period of growth prior to achieving sexual maturity to observe their response to photoperiod stimulation. Birds were sampled at regular intervals to measure the average testis weight these values respon...

The differential allocation hypothesis predicts that reproductive investment will be influenced by mate attractiveness, given a cost to reproduction and a tradeoff between current and future reproduction. We tested the differential allocation hypothesis in the swordtail fish Xiphophorus multilineatus, where males have genetically influenced (patroclinous inheritance) alternative mating tactics ...

The development of sexual maturity in Tetrahymena thermophila has been shown to include an intermediate stage, adolescence, during which cells are capable of mating with mature cells but not other adolescent cells. When the progeny of successfully mated cells are grown logarithmically and tested frequently for the ability to mate, they are unable to form mating pairs for about 65 generations. T...

Human immunodeficiency virus (HIV) infection has increased considerably among middle-aged women. In this work we reviewed recent studies aimed at identifying possible factors related to HIV infection in climacteric women. Several associated factors are considered, such as: climacteric symptoms, partner's change in sexual behavior in face of new drugs, negotiation for use of condoms in sexual in...

Since sturgeons have no external sexual dimorphism and there are no external markers to determine sex, internal examination of the gonads should be used to sex identification. The present study describes the biopsy method and histological observations of the gonads of great sturgeon (Huso huso) in both sexes at different age classes. Sex and maturity stages of 226 great sturgeons were identifie...