Surface and Surface-to-Volume Relationships of the Sertoli Cell during the Cycle of the Seminiferous Epithelium in the Rat1

Abstract

The surface relationships of the Sertoli cell and the surface relationships of the Sertoli cell in comparison to the changing volumes of developing germ cells were studied using morphometric techniques at periods representing nine groupings of the fourteen defined periods in the cycle of the seminiferous epithelium of the adult rat. No cyclic variation in the total Sertoli plasma membrane surface area was noted. Cyclic variations were noted in the area of the Sertoli cell surface that faces the basal compartment germ cells, but not the basal lamina. No cyclic variations were noted in the amount of contact of the Sertoli cells with each other at the level of the Sertoli cell barrier. However, when areas in the adluminal compartment were studied, significantly less Sertoli-Sertoli contact was seen in stages V through VII than in other stages with the exception of stages II-IV. Surface contact of germ cells with Sertoli cells increased progressively as germ cells entered the intermediate compartment and progressed to late spermatids. However, a calculation of the surface-to-volume ratio showed that surface increases of the Sertoli cell in relation to the volume of germ cells were greatest in elongating spermatids past step 12 of spermiogenesis. The area in which Sertoli ectoplasmic specializations faced germ cells was determined throughout spermatogenesis, and these data demonstrated that the first appearance of ectoplasmic specialization was at the mid-pachytene phase. They also showed that stage VIII was a period when ectoplasmic specialization loss from the cell surface was evident. Less Sertoli ectoplasmic specialization face step 8 and step 19 spermatids than comparable germ cell types at other stages. In addition to Sertoli cell surface area changes during the cycle, volumes of individual germ cell types were determined for the first time. The data presented allow an objective understanding of the complex structure and relationships of the Sertoli cell and provide a basis for understanding functional changes and interpreting biochemical data.

Stage-specific gene expression is a fundamental characteristic of rat spermatogenic cells and Sertoli cells

“…Cell movement requires marked changes in cell shape, volume, cytoskeleton organization, and interaction with other cells. It is, therefore, noteworthy that there are marked stage-regulated changes in the volume and surface area of Sertoli cells, as well as in the amount of Sertoli cell plasma membrane in contact with spermatogonia, spermatocytes, and spermatids (37,44). Therefore, although the Sertoli cells do not themselves move, the changes that they undergo are consistent with their role in moving germ cells from the basement membrane to the lumen of the seminiferous tubule.…”

“…Gpc4 is a GPI-anchored heparin sulfate proteoglycan that binds to growth factors, including FGF-2, and thereby modulates their effects on target cells (31,36). FGF-2 is produced by pachytene spermatocytes (37). Dpysl4 transduces the signal that is generated by the binding of the semaphorin family of signaling molecules to a heterodimeric cell surface receptor encoded by a member of the plexin family and by RhoA (33).…”

Anchoring Junctions As Drug Targets: Role in Contraceptive Development

“…For instance, Sertoli cells have been shown to assume various shapes throughout different stages of the epithelial cycle (Russell, 1993c;Vogl et al, 1993;Hess and Franca, 2005). In fact, it has been reported that as much as ϳ40% of the Sertoli cell surface is in contact with elongated spermatids alone (Russell et al, 1986;de França et al, 1993), illustrating that the interaction between the Sertoli cell and this germ cell type is enormous. Indeed, a single Sertoli cell is known to support ϳ30-40 germ cells at different stages of development (Weber et al, 1983;Wong and Russell, 1983).…”

Sertoli cell anatomy and cytoskeleton

“…This anatomical complexity, which has been described in detail in previous editions of this book, is now the focus of numerous studies to help us understand how different functions are organized both within the cytoplasm and along the plasma membrane. Total surface area of the Sertoli cell plasma membrane varies between 12,000 and 16,000 μm 2 , depending on the stage of the cycle of spermatogenesis [19]. Morphological changes in Sertoli cells over the course of the cycle are dramatic and involve the translocation of numerous organelles, expression of a large number of proteins for specific functions, and changes in the location of these proteins throughout the cycle [5,7,22,36,163À165].…”