seminiferøse

Seminiferøse (seminiferous) tubules are the functional units of the testes, organizing the production of sperm. They are highly coiled tubular structures housed within the testicular parenchyma and arranged into lobules. Each tubule is bounded by a basement membrane and has an outer layer of myoid cells, with an inner germinal epithelium composed of Sertoli cells and a spectrum of germ cells at successive stages of development. The lumen contains differentiating spermatozoa and residual cytoplasm.

Function: Spermatogenesis occurs in the seminiferous epithelium. Spermatogonia undergo mitosis, giving rise to primary spermatocytes that enter meiosis and produce haploid spermatids. Through spermiogenesis, spermatids mature into spermatozoa that are released into the tubule lumen and transported through the reproductive tract. Sertoli cells nourish developing germ cells, form the blood–testis barrier via tight junctions, phagocytose residual cytoplasm, and respond to follicle-stimulating hormone (FSH). Leydig cells in the interstitial tissue secrete testosterone, which supports spermatogenesis and Sertoli cell function.

Structure and connections: The seminiferous tubules connect at the tubuli recti to the rete testis, which channels sperm into the efferent ducts toward the epididymis. The arrangement maximizes surface area for cell division and differentiation.

Clinical relevance: Abnormal seminiferous tubules underlie many causes of male infertility, including impaired spermatogenesis, obstruction, or germ cell tumors. Pathology can include Sertoli cell-only syndrome, maturation arrest, or intratubular germ cell neoplasia.

Terminology: In Danish, "seminiferøse" is used as the adjective form for seminiferous; in English texts the term "seminiferous" is common.