The barrier also prevents passage of cytotoxic agents (bodies or substances that are toxic to cells) into the seminiferous tubules.

The fluid in the lumen of seminiferous tubules is quite different from plasma; it contains very little protein and glucose but is rich in androgens, estrogens, potassium, inositol and glutamic and aspartic acid.

[1] The barrier also protects the germ cells from blood-borne noxious agents,[1] prevents antigenic products of germ cell maturation from entering the circulation and generating an autoimmune response,[1] and may help establish an osmotic gradient that facilitates movement of fluid into the tubular lumen.

[1] The blood–testes barrier can be damaged by trauma to the testes (including torsion or impact), by surgery or as a result of vasectomy.

The anti-sperm antibodies generated by the immune system can bind to various antigenic sites on the surface of the developing sperm within the testes.