Spermatogenesis and Cycle of the Seminiferous Epithelium

Abstract

Spermatogenesis is a complex biological process of cellular transformation that produces male haploid germ cells from diploid spermatogonial stem cells. This process has been simplified morphologically by recognizing cellular associations or 'stages' and 'phases' of spermatogenesis, which progress through precisely timed and highly organized cycles. These cycles of spermatogenesis are essential for continuous sperm production, which is dependent upon numerous factors, both intrinsic (Sertoli and germ cells) and extrinsic (androgens, retinoic acids), as well as being species-specific.

Downregulation of Col1a1 induces differentiation in mouse spermatogonia

“…33 Mitosis occurs in SSCs residing in the basal compartment to produce additional germ cells, some of which differentiate into type B spermatogonia and primary preleptotene spermatocytes. 34,35 During their transit at the BTB, preleptotene spermatocytes differentiate into diplotene spermatocytes, and then enter metaphase I to undergo meiosis I and meiosis II which produces haploid spermatids in the apical compartment 36,37 . Collagen is one of the most abundant ECM proteins in basement membrane, and the basement membrane and integrins act as anchorage for undifferentiated spermatogonia.…”

Stress and Cell Death in Testicular Cells

“…These cells are mitotically divided to produce more spermatogonia; some of them mature and differentiate in type A spermatogonia, which are mitotically divided into spermatogonia, and later in type B spermatogonia. The latter divide once or twice by mitosis to form primary spermatocytes, which initiate the first meiotic division to form secondary spermatocytes, which start rapidly the second meiotic division, As a result of the second meiotic division, each secondary spermatozoon forms two rounds spermatids, each with a haploid number of 23 chromosomes in the human [6][7][8][9][10]. Once formed, the spermatids are transformed into functional spermatozoa by series of progressive morphological changes called collectively as spermiogenesis (Figure 1) [9,10].…”

“…The latter divide once or twice by mitosis to form primary spermatocytes, which initiate the first meiotic division to form secondary spermatocytes, which start rapidly the second meiotic division, As a result of the second meiotic division, each secondary spermatozoon forms two rounds spermatids, each with a haploid number of 23 chromosomes in the human [6][7][8][9][10]. Once formed, the spermatids are transformed into functional spermatozoa by series of progressive morphological changes called collectively as spermiogenesis (Figure 1) [9,10]. In the seminiferous epithelium, germ cells present associations that progress very precisely over time and are organized cyclically [7,8], according to their different stages of development and differentiation.…”

“…In the seminiferous epithelium, germ cells present associations that progress very precisely over time and are organized cyclically [7,8], according to their different stages of development and differentiation. In the rat, spermatogenesis is divided into XIV cell stages or associations that constitute the cycle of the seminiferous epithelium, which lasts from 48 to 52 days [7,9,10]. Spermatogenesis is carried out in close association with the Sertoli cells, the only somatic cells of the seminiferous epithelium; which are responsible for providing structural, nutritional and endocrine support to the developing germ cells [11,12].…”

“…There are currently animal models that are used to study the effect of stress, such as immobilization [41], unpredictable chronic stress [10], cold water immersion [42] or hot stress [43], applied in rats. These types of stressors trigger the activation of the HHA axis stimulating glucocorticoid secretion from the adrenal cortex, into the systemic circulation.…”