Elastic tissue in the limiting membrane of the human seminiferous tubule

Profound Effects of Dexamethasone on the Immunological State, Synthesis and Secretion Capacity of Human Testicular Peritubular Cells

The functions of human testicular peritubular cells (HTPCs), forming a small compartment located between the seminiferous epithelium and the interstitial areas of the testis, are not fully known but go beyond intratesticular sperm transport and include immunological roles. The expression of the glucocorticoid receptor (GR) indicates that they may be regulated by glucocorticoids (GCs). Herein, we studied the consequences of the GC dexamethasone (Dex) in cultured HTPCs, which serves as a unique window into the human testis. We examined changes in cytokines, mainly by qPCR and ELISA. A holistic mass-spectrometry-based proteome analysis of cellular and secreted proteins was also performed. Dex, used in a therapeutic concentration, decreased the transcript level of proinflammatory cytokines, e.g., IL6, IL8 and MCP1. An siRNA-mediated knockdown of GR reduced the actions on IL6. Changes in IL6 were confirmed by ELISA measurements. Of note, Dex also lowered GR levels. The proteomic results revealed strong responses after 24 h (31 significantly altered cellular proteins) and more pronounced ones after 72 h of Dex exposure (30 less abundant and 42 more abundant cellular proteins). Dex also altered the composition of the secretome (33 proteins decreased, 13 increased) after 72 h. Among the regulated proteins were extracellular matrix (ECM) and basement membrane components (e.g., FBLN2, COL1A2 and COL3A1), as well as PTX3 and StAR. These results pinpoint novel, profound effects of Dex in HTPCs. If transferrable to the human testis, changes specifically in ECM and the immunological state of the testis may occur in men upon treatment with Dex for medical reasons.

The Glucocorticoid Receptor NR3C1 in Testicular Peritubular Cells is Developmentally Regulated and Linked to the Smooth Muscle-Like Cellular Phenotype

Whether glucocorticoids (GC) can directly affect human testicular functions is not well understood. A predominant site of GC receptor (GR; NR3C1) expression in the adult testis are peritubular smooth muscle-like cells, which express smooth muscle actin (ACTA2), contract and thereby are involved in sperm transport. In contrast to the adult, neither GR nor ACTA2, or elastin (ELN) were detected in the peritubular compartment before puberty in non-human primate testes. In isolated human testicular peritubular cells (HTPCs), activation of GR by dexamethasone (Dex) caused the translocation of GR to the nucleus and stimulated expression of ACTA2 and ELN, without affecting the expression of collagens. Cytoskeletal ACTA2-rearrangements were observed and were associated with an increased ability to contract. Our results indicate post-pubertal testicular roles of GC in the maintenance of the contractile, smooth muscle-like phenotype of peritubular cells.

The lamina propria of vertebrate seminiferous tubules: a comparative light and electron microscopic investigation

The lamina propria of the seminiferous tubules was compared by means of light and electron microscopy in specimens obtained from the following vertebrates: Mute swan, northern mallard, blackbird, grey short-tailed opossum, north american opossum, european rabbit, mouse, rat, golden hamster, mini pig, bull, llama, roebuck, horse, coati, cat, dog, java monkey, orang utan. The lamina propria consists of basal lamina, ground substance, collagen fibers, fibroblasts and myofibroblasts. Myofibroblasts are characterized by myofilaments, dense patches and a basal lamina covering their plasmalemma. The layers of myofibroblasts always lie adjacent to the germinal epithelium, while the surrounding fibroblast layers are located peripherally.

Ultrastructure of the lamina propria of the human ductuli efferentes and ductus epididymidis

The cellular and connective tissue constituents of the lamina propria of the ductuli efferentes and the ductus epididymidis of prepubescent, adult and senescent men were studied by means of electron microscopy. Layers of contractile cells showing features of smooth muscle cells, alternate with interstitial layers of connective tissue fibers. Additionally to collagenous fibers, in the interstitial layers three types of elastic system fibers, oxytalan, elaunin and elastic, were evident, differing by their varying amount of elastin. Oxytalan fibers, lacking the amorphous component elastin, were present in almost all intercellular spaces along the excurrent duct system, closely related to the contractile cells. They were the only type of elastic system fibers recognizable in the prepubescent epididymal lamina propria. However, in the adult and senescent men, elastin deposits were observed in the middle and outer layers of the lamina propria. In these cases the elaunin and elastic fibers appeared to increase with the gradual proximo-distal thickening of the subepithelial coat of contractile cells. In senescent men, only in few cases the epididymal lamina propria showed some alterations. It is suggested that these changes are not related to age but more likely to the state of individual testicular function. The functional significance of the special architecture of the epididymal lamina propria is discussed.