The androgenic induction of spinal sexual dimorphism is independent of supraspinal afferents.

On the day of birth, female rats received either a thoraco-lumbar spinal transection or sham operation, followed by administration of either testosterone propionate (TP) or oil immediately after surgery and again on the third day of life. Upon sacrifice at 30 days of age examination of spinal cords revealed that TP masculinized the spinal nucleus of the bulbocavernosus (SNB) in terms of cell number, soma size, and nuclei size. The perineal muscles innervated by the SNB were present only in those rats which received TP. Neonatal transection did not alter any of these effects of androgen treatment. Thus, supraspinal afferents are unnecessary for androgen induction of sexual dimorphism in the SNB. Remaining candidates for the site of androgen action include the SNB motoneurons and/or muscles themselves.