Effect of androgens on the cranial suspensory ligament and ovarian position

Androgens have been postulated to have a major role in testicular descent via regression of the cranial suspensory ligament, which in normal rodents anchors the ovary to the retroperitoneum near the lower pole of the kidney. This study aimed to quantitate the degree of descent of the foetal ovary in androgen-treated female mice to determine the role of androgens in regression of the cranial suspensory ligament and descent of the testis. Time-pregnant mice were injected with testosterone propionate or methyl testosterone (2.5-3.0 mg) in vehicle on day 13 or 14. Control animals received vehicle only. Newborn mice were anaesthetised and dissected for macroscopic anatomy of the ovary, which was quantified by measuring the vertical distance from the lower pole of the kidney to the lower pole of the ovary. Histological analysis was also performed. The external genitalia were masculinised in all females exposed to prenatal androgens. The ovaries of treated animals were mobile, with no cranial suspensory ligament, and located slightly caudal to the kidney. Wolffian duct structures were identifiable, but the gubernaculum was qualitatively unchanged compared with control females. The ovary was displaced caudally (P< 0.001), but only 15-25% of the distance to the lower abdomen. Exogenous androgens induce regression of the cranial suspensory ligament, causing the ovary to be more mobile and lower in the abdominal cavity. However, since the testicular position at birth is at or below the bladder neck, androgen-mediated regression of the cranial suspensory ligament is only an adjunct to the control of transabdominal testicular descent.