119 research outputs found
A new translation and reader's guide to Victor von Ebner's classical description of spermatogenesis
Untersuchungen �ber die Degeneration samenbildender Zellen in der normalen Spermatogenese der Ratte
Sperm competition and sperm length influence the rate of mammalian spermatogenesis
Sperm competition typically favours an increased investment in testes, because larger testes can produce more sperm to provide a numerical advantage in competition with rival ejaculates. However, interspecific variation in testis size cannot be equated directly with variation in sperm production rate—which is the trait ultimately selected under sperm competition—because there are also differences between species in the proportion of spermatogenic tissue contained within the testis and in the time it takes to produce each sperm. Focusing on the latter source of variation, we provide phylogenetically controlled evidence for mammals that species with relatively large testes (and hence a high level of sperm competition) have a shorter duration of the cycle of the seminiferous epithelium and consequently a faster rate of spermatogenesis, enabling males to produce more sperm per unit testis per unit time. Moreover, we identify an independent negative relationship between sperm length and the rate of spermatogenesis, such that spermatogenesis takes longer in species with longer sperm. We conclude that sperm competition selects for both larger testes and a faster rate of spermatogenesis to increase overall sperm production, and that an evolutionary trade-off between sperm size and numbers may be mediated via constraints on the rate of spermatogenesis imposed by selection for longer sperm
Classification of plastic-embedded rat seminiferous epithelium prior to electron microscopy
Autoradiographical investigation on the kinetics of the spermatogenesis in the wistar rat especially of the spermatocytogenesis
Quantitation of the cells of the seminiferous epithelium of the human testis employing the Sertoli cell as a constant
Stage-dependent topographical relationship of spermatogonia and early spermatocytes to Sertoli-Sertoli interspaces in the rat testis
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