Cellular architecture of the lamina propria of human seminiferous tubules

Abstract

The lamina propria of human seminiferous tubules is composed of 5 to 7 cellular layers separated by laminae of extracellular connective-tissue components. By means of immunocytochemical methods the different nature of the cellular layers could be defined for the first time. Based on the light-microscopic demonstration of both desmin-like and vimentin-like immuno-reactivity in the inner 3 to 4 layers of the lamina propria, these cells can be identified as myofibroblasts. The outermost one or two cellular layers, on the contrary, only show a vimentin-like immunoreactivity indicating the pure fibroblastic nature of these cells. Therefore, the outermost cellular layers are suggested to be derivatives of the interstitium. In cases of disturbed spermatogenesis, the lamina propria is frequently considerably thickened by an increase in the extracellular matrix components between the cellular layers. Whereas the ultrastructural localization of laminin-, collagen type-IV- and fibronectin-like immunoreactivity remains unaffected in the thickened lamina propria, the desmin-like immunoreactive cells of the inner layers strongly decrease in number and staining intensity. Most probably, the myofibroblasts lose their myoid characteristics to participate in the secretion of increased amounts of extracellular matrix components, which in turn presumably block the mediation of the lamina propria between the interstitium and the germinal epithelium. It is still unclear whether the thickened lamina propria provokes the disturbance of spermatogenesis or vice versa.

Human testicular peritubular cells: more than meets the eye

“…Differences in the cellular phenotypes between the inner and outer layers in man were suggested, according to results of immunohistochemical studies. The inner layers stained with desmin, supporting their smooth muscle phenotype, while the outer ones stained mainly with vimentin, implying a connective tissue phenotype (Davidoff et al 1990). The smooth muscle characteristic, i.e.…”

Building the mammalian testis: origins, differentiation, and assembly of the component cell populations

“…In smaller rodents, the PMC sheet is only one cell layer thick, whereas in larger mammals, it typically consists of multiple layers separated by extracellular connective tissue . This boundary tissue-the lamina propria that helps separate tubules from interstitium and acts as contractile tissue to facilitate sperm export-typically consists of PMCs and ECM, although in humans, fibroblast cells (myofibroblasts) also occupy the outer layers of the lamina propria (Davidoff et al 1990;Dym 1994;Holstein et al 1996). The composition of ECM is contributed by both PMC and Sertoli cells (Tung et al 1984;Georg et al 2012).…”

Testis peritubular myoid cells increase their motility and express matrix‐metalloproteinase 9 (MMP‐9) after interaction with embryonal carcinoma cells

“…This variable impact of the soluble factors present in the conditioned medium might be explained by the presence of two or more subpopulations of PTCs in our cultures. Actually, the existence of different PTC types with distinct phenotypic characteristics has been described in human PTC samples (Davidoff et al, 1990).…”