Sertoli cell origin of testicular androgen-binding protein (ABP)

In this report it is suggested that the specific adrogen-binding protein (ABP), previously shown to originate in the testis of rat and other species, is produced by the Sertoli cells. This suggestion is based upon the following experimental findings: 1) ABP was found in high concentrations in testicular efferent duct fluid but only in trace amounts in inter-tubular lymph. i) ABP could be recovered from crude preparations of testis tubules, but not from Leydig cells from the same testes. 3) Testes whose germinal epithelium had been severly damaged by gamma irradiation showed no decrease in ABP content. The transport of ABP to epididymis was also preserved as judged from the levels of ABP in caput epididymis. 4) Testes that were completely devoid of germ cells following prenatal gamma irradiation showed high levels of ABP, These high levels approached zero following hypophysectomy, but could be restored by FSH administration to the hypophysectomized animals. ABP has been well characterized and now provides a valuable experimental tool as an indicator of Sertoli cell function.