The fetal rat gubernaculum contains higher levels of androgen receptor than does the postnatal gubernaculum.

The androgen receptor of the rat gubernaculum was measured by a sensitive immunoblotting technique from day 19 of fetal development to day 20 of postnatal development. In relative terms (densitometric units/microgram. protein), it was found that the amount of the gubernacular androgen receptor decreased dramatically from fetal to postnatal development, coincident with the transition of the gubernaculum from a tissue primarily composed of undifferentiated mesenchymal cells in the fetus to a tissue that is primarily made up of muscle during postnatal development. We conclude that the undifferentiated mesenchyme of the fetal gubernaculum is a primary target of androgen action.