Which of the following is not true about blood testis barrier?

Ans. b. It is formed before primary spermatogenesis (Ref: Ganong 23/e p. 402-3; Grays Anatomy 40/e pe p1265-67, 1317-20)Blood Testis Barrier:Germ cells are not necessary for formation of the barrierFormed by Sertoli cells (Blood testis barrier is located between sertoli and sertoli cells.)Any rupture of barrier can cause immune response to germ cells: Blood testes barrier protects the developing sperms from immunologic attack and blood borne noxious agentsQFunctions of Sertoli CellsSertoli cells are specialized cells within the seminiferous tubules that are involved in the orchestration and coordination of all the key events during spermatogenesis and spermiogenesisQ.Provide support, nutrition to developing spermatozoaQ:The cells of spermatogenic series are physically supported by extensive cytoplasmic ramification of sertoli cells. Sertoli cells provide nutrition to cells of spermatogenic series.Protect developing germ cells by forming Blood Testes BarrierQ:Sertoli cells are linked by tight junctionsQ, the strongest intercellular harriers in the body.This arrangement forms the blood testes barrierQ.Blood testes barrier protects the developing sperms from immunologic attack and blood borne noxious agentsQSecretion of important substances:Secrete androgen binding proteinQSecrete inhibinQSecrete Mullerian inhibiting substanceQContain aromataseQ (CYP): This can convert testosterone to estrogenPresence of FSH receptors:Sertoli cells have high affinity FSH receptorsQ that bind FSHFSH binding stimulates the production of androgen binding protein, which concentrates testosterone. Spermatogenesis requires the presence of FSH and high mtratesticular levels of testosterone.Role in spermiogenesis (Phagocytosis):Spermiognesis is the process by which spherical spermatids are transformed into elongated spermsQ.Sertoli cells play an important role in the final maturation phase of spermiogenesis, which is characterized by shedding of excess or residual cytoplasm of the spermatids.Sertoli cells phagocytose this excess residual cytoplasm and thus helps in spermiogenesisQ.