Spermatogenesis and Sertoli cell numbers and function in rams and bulls

Abstract

The two main types or cellular associations (type I. 2 generations of spermatocytes + 1 of spermatids, type II, 1 of spermatocytes and 2 of spermatids) occupy. respectively, more than half and about a third of the seminiferous epitheliurn cycle in rams and bulls. However, the duration of the cycle of the seminiferous epithelium and that of spermatogenesis differ between the species. A, spermatogonia and Sertoli cell total numbers are highly correlated in adult rams and bulls. Mitosis in Sertoli cells occurs mostly ill ellero but may still occur for a short period after birth. Between birth and puberty there is about a 5-fold increase in the number of Sertoli cells. After tha t there are no seasonalor age-related increases in the number of adult Sertoli cells. Some factors (season of birth, nutrition: genetics: hormones) affect mitosis of Sertoli cells in prepubertal animals. Sertoli cells differentiate after cessation of mitosis. Their differentiation is affected by cryptorchidism. nutrition, genetics and hormones. Their adult ruaction is only poorly known_ ABP and rete testis fluid secretions and nuclear Sertoli volume fluctuate under the influence of the same factors. but they are not always linked together. This reinforces the need tior more knowledge a Sertoli cell secretions and function.

Effect of plane of nutrition during the first 12 weeks of life on growth, metabolic and reproductive hormone concentrations, and testicular relative mRNA abundance in preweaned Holstein Friesian bull calves

“…Previous studies have shown that larger testicular size in the bull calf, as a consequence of improved calfhood nutrition, is consistent with advanced morphological ontogenesis in the form of greater seminiferous tubule development as well as greater Sertoli cell number and spermatogenic capacity ( English et al, 2018b ). This is important as Sertoli cell number does not increase after puberty in bulls, between birth and puberty, there is an approximate 5-fold increase in the number of Sertoli cells but after that there are no seasonal- or age-related increases in the number of adult Sertoli cells ( Hochereau-de Reviers et al, 1987 ).…”

Reproductive Management of Rams and Ram Lambs during the Pre-Breeding Season in US Sheep Farms

“…This induces production of viable spermatozoa and results in an increase in sexual behaviors (libido, aggressiveness, etc.) [6,7]. By the beginning of the breeding season (late August to September in the northern hemisphere), resumption of testicular activity and increased concentration of reproductive hormones (GnRH, LH, FSH and Testosterone) are expected [8][9][10].…”

Review: Spermatogenesis in the bull

“…Therefore, a proportion of the A 1 spermatogonia divide to renew the population of A 1 spermatogonia and the remainder divides into A 2 spermatogonia which engage in the spermatogenetic process. Moreover, Kramer (1960) and Amann (1962b) propose a model of asynchronous spermatogonial generations (Figure 5c) which is not shared by Ortavant (1959) and Hochereau-de Reviers (1970, 1971 and Hochereau-de Reviers et al (1987) (Table 1).…”