sperm qualityIn polyandrous species, a male's reproductive success depends on his ability to fertilize females which, in turn, depends on his mating ability and his ability to produce competitive ejaculates. In many species, sperm traits differ between old and young males in ways that are ...
Abnormal spermatid elongation affects male fertility since SR males produce 74% as many progeny per week as ST males. The proportion of spermatocyst bundles with improperly elongated spermatid nuclei explains 71% of the variation in progeny sex proportion. After reviewing the literature on sperm ...
Rather, older males produced bigger spermatophores of higher nutritional value and containing more sperm. Male age and mating history seem likely to be strongly correlated in the field. We conclude that female E. ephippiger probably prefer the songs of younger males, because in the field, this...
The gender difference in children is smaller than that in adults according to the upper limits of reference for adults (4.94 ng/mL in males and 2.88 ng/mL in females) on reagent specification of the Roche Group. This finding further supports the need to establish a upper reference limit of...
Starting atabout 4 to 5 months of age, young roosters (cockerels) reach sexual maturity, producing sperm and acting like roosters. They can remain fertile for several years, although the quantity and quality of sperm that roosters produce decreases as they age. ...
Of course, it is true that there are a minority of infertile oligospermic males who have either Sertoli cell only syndrome with no spermatogonia, or simply vastly reduced total spermatogenesis starting from the spermatogonial level. These men generally have an elevated FSH. However, they...
40 According to this hypothesis, de novo spontaneous mutations could arise, propagate, and accumulate in successive generations of sperm-producing cells (spermatogonia). These could be point mutations or structural chromosomal abnormalities41-43 that might account for the association between paternal age ...
Abnormal spermatid elongation affects male fertility since SR males produce 74% as many progeny per week as ST males. The proportion of spermatocyst bundles with improperly elongated spermatid nuclei explains 71% of the variation in progeny sex proportion. After reviewing the literature on sperm ...
Ejaculate expenditures of male crickets in response to varying risk and intensity of sperm competition: not all species play games. Costs incurred in the manufacture of ejaculates may constrain the number of sperm that males can produce, so males should show some economy in their alloca... JM ...
Based on sexual selection theory, the reproductive potential of male primates is expected to be limited by access to fertile females. Alpha males, the highest ranking males in a social group, are predicted to have better access to mates and produce more