composed primarily of Sertoli cell squamous epithelium haemolymphatic fluid-testis barrier Sertoli cell barrier blood-testes barrier blood testis barrier The blood-testis barrier (abbreviated as BTB) is a physical barrier between the blood vessels and the seminiferous tubules of the animal testes. The barrier is formed by tight connections between the Sertoli cells, which are sustentacular cells (supporting cells) of the seminiferous tubules, and nourish the spermatogonia. The barrier prevents passage of cytotoxic agents (bodies or substances that are toxic to cells) into the seminiferous tubules. MESH:D001814 UBERON:0036185 Wikipedia:Blood-testis_barrier