Spermatogenesis and Morphology of the Spermatozoon

The Effect of Local Heating on the Flow and Composition of Rete Testis Fluid in the Conscious Ram

“…However, in two rams (2 and 3), the observations were concluded before any alteration in the production of spermatozoa would be expected and in the other, the second period ofobservations was not begun until 55 days after unilateral castration when the production of spermatozoa would have reached its new level (Voglmayr & Mattner, 1968;Voglmayr & Setchell, unpublished observations). From the known time sequence of spermatogenesis in sheep (Ortavant, 1959) Waites & Ortavant (1968) was the abortive division of the type-B spermatogonia, which is consistent with the secondary fall in sperm concentration being greater than the initial fall. The marginal losses in spermatids described by Waites & Ortavant (1968) were not reflected in any changes in the output of spermatozoa up to 20 days after heating, but it is apparent from the higher percentage of abnormal spermatozoa seen in semen before the fall in sperm concentration and the fact that the number of spermatozoa in ejaculates falls as early as 11 days after heating (Waites & Setchell, 1964) that more subtle damage is done to later stages of spermatogenesis.…”

Aspects of spermatogenesis and microscopic testicular morphology in Greater Rhea, Rhea americana (Linnaeus, 1758)

“…In the samples of November/2005 and December/2006, the epithelium exhibited various cellular types during visible spermatogenic process (Fig.3), spermatogonia through all of the basal expansion of the tubules and primary spermatocytes was observed (leptotene and pachytene), however, none of these cells encountered were at the anaphase stage, it is known that this stage occurs rapidly (Ortavant 1959) in birds as well as in mammals. Secondary spermatocytes were seldom seen and hardly visible in the histological sections of the Greater Rhea because of their short lifespan.…”

Spermatogenesis in Mature and Regressed Testes of the Vole (Microtus Agrestis)

“…Since testes from voles kept in short photoperiods, or trapped in the field in winter, are very often much more regressed than those studied here, cell losses frequently must be even greater. The seasonal changes in spermatogenesis in the vole and other species appear to be due to alterations in the number of cells surviving rather than to changes in the rate of spermatogenesis, which has been regarded as constant for any one species (Ortavant et al, 1969). Testis and seminal vesicle weights (Table 1) suggest that circulating levels of gonadotrophins and testicular hormones were lower in the voles with regressed testes than in the sexually mature animals.…”