Seasonal Changes in Spermatogenesis of the Japanese Lesser Horseshoe Bat, Rhinolophus cornutus from a Morphological Viewpoint.

Abstract

Seasonal changes in spermatogenesis of Japanese lesser horseshoe bats, Rhinolophus cornutus, captured in Aomori Prefecture (Japan) were examined by light microscopy. In March, the seminiferous tubules revealed almost no lumen. The seminiferous epithelium consisted of Sertoli cells and spermatogonia. The interstitium occupied a relatively large area. In June, the seminiferous tubules gradually increased in diameter. Lumen was clearly seen at the center of seminiferous tubules. Mitotic figures of spermatogonia and spermatocytes were occasionally recognized. Interstitium occupation was still abundant. In August, the diameter of seminiferous tubules maximized. The interstitium occupied only a small area. Active spermatogenesis was obvious at this time. Released spermatozoa were frequently observed within the expanded lumen. In October, although spermatogenesis was still active, the diameter of seminiferous tubules tended to decrease in size. In December, active spermatogenesis completely disappeared. The diameter of tubules greatly decreased. In most cases, the seminiferous epithelium contained only Sertoli cells and spermatogonia. Thus, spermatogenesis in Japanese lesser horseshoe bats occurs from the middle or late summer to the middle autumn in Aomori Prefecture. In epididymal tracts, aggregated spermatozoa were recognized throughout the year. The cytoplasm of all Leydig cells in the interstitium was positive for 3beta-hydroxysteroid dehydrogenase throughout the year.

Ultrastructural characteristics of spermatogenesis in Pallas's mastiff bat, Molossus molossus (Chiroptera: Molossidae)

“…Spermatogenesis is a highly regulated and synchronized process of cellular differentiation, whereby stem cells proliferate, divide meiotically, and gradually differentiate into highly specialized haploid cells, spermatozoa (Costa and Paula,2003; Matsumoto,1996). The main events of this process are generally similar in most mammals (Adachi et al,1992; Foote et al,1972; Kurohmaru et al,2002; Osman and Ploen,1986; Oud and de Rooij,1977; Painter,1923; Swierstra and Foote,1963; Wodsedalek,1914); however, variations in the process among and within orders, families, and taxa are frequently observed (Lin and Jones,2000; Lin et al,1997; Phillips et al,1997), being mainly determined by variations in the final structure of the spermatozoon (Beguelini et al,2011a; Jamieson,1995).…”

Morphological characterization of the testicular cells and seminiferous epithelium cycle in six species of Neotropical bats

“…The occurrence of variations in the composition and function of the seminiferous epithelium with regard to the annual breeding cycle in bats has been described specifically for hibernating bats (Racey, 1974;Kurohmaru et al, 2002;Lee, 2003;Encarnaçã o et al, 2004;Lee and Mori, 2004;Sharifi et al, 2004). A process of spermatogenic cell degeneration in the seminiferous tubules occurs prior to hibernation, after which the spermatogenic process is restarted by elevated levels of testicular and plasma testosterone that induce an overproduction of new spermatogenic cells (Racey and Tam, 1974;Gustafson and Shemesh, 1976;Gustafson and Damassa, 1985).…”

“…Although testicular histoarchitecture and seasonal changes in the germinal epithelium, the Sertoli cells and the Leydig cells have been described in some oriental and occidental species of Micro-and Mega-chiroptera, information about the kinetics of the process is still scarce (Anand Kumar, 1965;Racey and Tam, 1974;Singwi and Lall, 1983;McGuckin and Blackshaw, 1987;Saidapur and Patil, 1992;Entwistle et al, 1998;Morigaki et al, 2001;Kurohmaru et al, 2002;Lee, 2003;Sharifi et al, 2004).…”

Male reproductive cycle of hibernating Korean greater horseshoe bat,Rhinolophus ferrumequinum korai(Chiroptera: Rhinolophidae): annual cycle of the seminiferous epithelium and morphological changes of the testes

“…Recently, several studies have reported the periodicity of the seminiferous epithelium in bats, including spermatogenesis (Merwe & Rautenbach 1987;Morigaki et al 2001;Kurohmaru et al 2002;Kang & Lee 2004;Lee & Mōri 2004;Sharifi et al 2004;Beguelini et al 2009Beguelini et al , 2011bBeguelini et al , 2012aBeguelini et al ,b, 2013Beguelini et al , 2014Morais et al 2012Morais et al , 2013Morais et al , 2014. Major events are similar in most species of bats.…”