Müllerian Inhibiting Substance Activity in Bovine Fetal, Newborn and Prepubertal Testes1

Abstract

A graded organ culture assay was used to detect Müllerian Inhibiting Substance activity in bovine testes. Müllerian Inhibiting Substance was present in all fetuses available for study from Day 110 to Day 210 of gestation. The assay detected similarly high activity during the first six weeks after birth. At eight weeks, activity was still present but diminished. Loss of activity, as in the rat, appeared to coincide with the time of weaning. Electron microscopic studies of the neonate calf testes demonstrate highly active Sertoli cells with a morphology suggestive of a protein secreting cell, and implicate the Sertoli cell as the source of Müllerian Inhibiting Substance. The neonate calf testes should be an excellent source of material for the isolation and biochemical characterization of Müllerian Inhibiting Substance.