Sertoli

Sertoli cells are specialized somatic cells located within the seminiferous tubules of the testis. They extend from the basement membrane to the tubule lumen and are bound by tight and gap junctions, forming the blood-testis barrier that divides the tubule into basal and adluminal compartments. Named after Enrico Sertoli, they are essential supporters of spermatogenesis and the testicular microenvironment.

Development and structure: Sertoli cells differentiate from the supporting gonadal lineage under genetic and hormonal cues, organizing the seminiferous epithelium and guiding germ cell maturation. Their long cytoplasmic extensions envelop developing germ cells, providing structural support and a regulated milieu for differentiation.

Functions and hormonal regulation: They provide nourishment and metabolic support to germ cells and phagocytose residual cytoplasm during spermiation. Sertoli cells secrete androgen-binding protein (ABP), which concentrates testosterone in the tubule to sustain spermatogenesis. They also produce anti-Müllerian hormone (AMH) during fetal development and continue to release inhibin B (and activin) to regulate FSH secretion. Sertoli cells express FSH receptors, making them responsive to follicle-stimulating hormone, and they have androgen receptors to respond to testosterone from nearby Leydig cells. They secrete growth factors such as GDNF that help maintain the spermatogonial stem cell niche.

Clinical relevance: Sertoli cell function can be assessed by inhibin B levels and AMH in certain pediatric and fertility contexts. Impaired Sertoli cell function contributes to male infertility, including Sertoli cell-only syndrome. Rare Sertoli cell tumors can arise from these cells. Overall, Sertoli cells are central to testicular architecture and the regulation of spermatogenesis.