Prespermatogenesis and spermatogoniogenesis in the bovine testis

Abstract

The bovine male germ cell population was studied over the entire period from testicular differentiation in the embryo through onset of spermatogenesis in the pubertal calf. Germ cells were identified by protein gene product 9.5 immunohistochemistry and characterized by their ultrastructure. The proliferation pattern of germ cells was studied with immunohistochemical anti-Ki 67 and anti-proliferating cell nuclear antigen reactions. Germ cells with a high proliferation rate are observed from day 50 p.c. to day 80 p.c. These cells are in transition from primordial germ cells to prespermatogonia. From day 80 p.c. until approximately the 15th postnatal week the germ cells present are identified as prespermatogonia. From day 80 p.c. to day 200 p.c. germ cell multiplication decreases continuously; then the prespermatogonia enter a phase of relative mitotical quiescence that lasts until the 4th postnatal week. Between the 4th and the 15th postnatal week, testicular tubular diameters grow from 40 to 80 microm and the prespermatogonia resume their proliferation. In seminiferous tubules with diameters between 80 and 120 microm, found in animals between 18 and 27 weeks of age, a central lumen is normally still absent. During this period germ cell proliferation reaches a second maximum. The cells involved represent the members of the spermatogonia stem and precursor cell line kinetically interpolated between the prespermatogonia and the first differentiating A-spermatogonia. This second phase of prepubertal germ cell multiplication coincides with the period when the pre-Sertoli cells transform into adult-type Sertoli cells and enter the G0-phase for the rest of life.

Desenvolvimento testicular, espermatogênese e concentrações hormonais em touros Angus

“…De fato, em estudos conduzidos com touros aos 12 meses de idade (52 semanas), uma média de 6,3 espermátides arredondadas por célula de Sertoli foi identificada em secções transversais de túbulos seminíferos . Considerando que as células de Sertoli não sofrem mitose após as 20 semanas de idade na espécie bovina (Sinowatz & Amselgruber, 1986), o aumento na proporção com as espermátides após esta idade é resultado do estabelecimento da meiose e da ampliação do pool de espermatogônias nos túbulos seminíferos Mackay, 2000;Wrobel, 2000;Walker, 2003). Portanto, a relação espermátide/célula de Sertoli é importante, pois reflete a capacidade de suporte das células de Sertoli e, em última instância, o potencial de produção Tabela 1 -Desenvolvimento do epitélio seminífero de touros Angus, em função dos estádios mais avançados das células germinativas , 1987).…”

Successful transplantation of bovine testicular cells to heterologous recipients

“…Successful male germ cell transplantation in rodents requires transfer to syngeneic or immunosuppressed recipients (Brinster & Zimmermann 1994, Dobrinski et al 1999, 2000, Shinohara et al 1999. In pigs and goats, allogeneic transfers have been successful (Honaramooz et al 2002a(Honaramooz et al , 2003b.…”

“…However, in bulls, the onset of spermatogenesis is delayed until several months after birth and development varies between breeds. In the Fleckvien breed, the prespermatogonia are still in a phase of relative mitotic quiescence until the 4th postnatal week, and expansion of spermatogonia reaches a maximum between 4 1 ⁄ 2 and 8 months of age (Wrobel 2000). However, in pure Brahman bulls, spermatogenesis starts at 9 months (Aponte et al 2005).…”

“…However, in pure Brahman bulls, spermatogenesis starts at 9 months (Aponte et al 2005). The rapid proliferation of germ cells and Sertoli cells during the onset of spermatogenesis leads to an increase in tubular diameter and testis size, which can be measured indirectly by changes in the scrotal circumference (SC) (Lunstra et al 1978, Wrobel 2000.…”

Age Related Changes in the Histoarchitecture of Seminiferous Epithelium in Mice

“…have been described in several domestic animal and avian species (Carmon and Green, 1952;Orsi et al, 1987;Sanchez et al, 1993;Wrobel, 2000;França and Godinho, 2003;Zayed and Moustafa, 1996;Kannan et al, 2015), whereas, the present study emphasised on the histomorphological changes in cellularity of seminiferous epithelium of mice.…”