<prompt> Blood testis barrier are present inSertoli cellsLeydig cellsPrimary spermatozoaSecondary spermatozoa  <response>: A. i.e. Sertoli cells 424- Ganong 22nd 403 - Ganong 23rd Tight junctions between adjacent sertoli cells near the basal lamina form a blood -testis barrier It prevents the entry of many substances from testicular interstitium into the lumen of seminiferous tubules Functions of sertoli cells1. Support and nourish the germ cells till the spermatozoa are released from them2. Provide hormonal and other substances necessary from spermatogenesis3. Convert androgens into estrogen4. Secrete - androgen binding protein ABP, Inhibin Mullerian regression factor MRF, Mullerian inhbiting substance MISBlood testis barrier helps maintaining the composition of the fluid in the lumen of the seminiferous tubules and also protects the germ cells from blood borne noxious agentsIt also prevents antigenic products of germ cell division from entering the circulation and generating an autoimmune responseIt contains high concentration of androgens, oestrogens, K, inositol glutamic and aspartic acid with low content of protein and glucose 808 - A.K. Jain 3rd 