INTRODUCTION Male fertility requires continual spermatogenesis, a process dependent on activities of an undifferentiated spermatogonial population composed of spermatogonial stem cells (SSCs) and transient amplifying progenitor spermatogonia (de Rooij and Russell, 2000; Oatley and Brinster, 2012). Self-renewal of SSCs maintains a constant pool from which progenitors will arise and amplify in nu...

I n males, sperm production begins at puberty and lasts throughout reproductive life. This implies that a population of germ stem cells/progenitors must be maintained, amplified and differentiate throughout life to enable the continuous supply of sperm. Spermatogenesis is indeed divided into three phases: a proliferative phase, a meiotic phase and a postmeiotic spermiogenic phase. In the prolif...

Research on spermatogonia is hampered by complex architecture of the seminiferous tubule, poor viability of testicular tissue ex vivo and lack of physiologically relevant long-term culture systems. Therefore there is a need for an in vitro model that would enable long term survival and propagation of spermatogonia. We aimed at the most simplified approach to enable all different cell types with...

BACKGROUND MicroRNAs (miRNAs) are critical regulators of transcriptional and post-transcriptional gene silencing, which are involved in multiple developmental processes in many organisms. Apart from miRNAs, mouse germ cells express another type of small RNA, piwi-interacting RNAs (piRNAs). Although it has been clear that piRNAs play a role in repression of retrotransposons during spermatogenesi...

BACKGROUND Water buffalo is an economically important livestock species and about half of its total world population exists in India. Development of stem cell technology in buffalo can find application in targeted genetic modification of this species. Testis has emerged as a source of pluripotent stem cells in mice and human; however, not much information is available in buffalo. OBJECTIVES A...

The immature part of the testis in the European fire salamander, Salamandra salamandra, consists of cephalo-caudally orientated zones of primary spermatogonia, secondary spermatogonia, primary spermatocytes, secondary spermatocytes and spermatids associated with follicle cells. Germ cells and follicle cells are arranged in lobules separated from each other by a vascularized connective tissue. P...

The pattern of ribonucleic acid synthesis during germ cell development, from the stem cell to the mature spermatid, was studied in the mouse testis, by using uridine-H(3) or cytidine-H(3) labeling and autoradiography. Incorporation of tritiated precursors into the RNA occurs in spermatogonia, resting primary spermatocytes (RPS), throughout the second half of pachytene stage up to early diploten...

All-trans retinoic acid (ATRA) is instrumental to male germ cell differentiation, but its mechanism of action remains elusive. To address this question, we have analyzed the phenotypes of mice lacking, in spermatogonia, all rexinoid receptors (RXRA, RXRB and RXRG) or all ATRA receptors (RARA, RARB and RARG). We demonstrate that the combined ablation of RXRA and RXRB in spermatogonia recapitulat...

Spermatogenesis in testes requires precise spermatogonia differentiation. Spermatocytes lacking the Rad9a gene are arrested in pachytene prophase, implying a possible role for RAD9A in spermatogonia differentiation. However, numerous RAD9A-positive pachytene spermatocytes are still observed in mouse testes following Rad9a excision using the Stra8-Cre system, and it is unclear whether Rad9a dele...

BACKGROUND The spermatogonial stem cell (SSC) pool in the testes of non-human primates is poorly defined. METHODS To begin characterizing SSCs in rhesus macaque testes, we employed fluorescence-activated cell sorting (FACS), a xenotransplant bioassay and immunohistochemical methods and correlated our findings with classical descriptions of germ cell nuclear morphology (i.e. A(dark) and A(pale...