Relationship between the development of the gubernaculum and the testicular descent in the rat fetus: Macroscopic and light and electron microscopic observation.

Abstract

The gubernaculum consists of the gubernacular cord connected with the vas deferens and the gubernacular bulb connected with the retroabdominal wall. The cord was first distinguished on day 15 of gestation. Its length reached the peak on day 16, followed by a reduction until day 18 to be almost constant thereafter. The bulb was first distinguished on day 16, and its length was steadily increased toward term. The testis began to descend with a reduced length of the cord. By day 19, the testis descended close to the caudal part of the bulb by the sharp bending of the cord. Microscopically, the bulb consisted at first of a centrally located mesenchymal mass and of a covering layer of myoblasts. Thereafter, the mesenchymal mass was gradually shifted toward the cranial part of the bulb, trailing loose mesenchymal tissue in the caudal part of the bulb. On day 19, the mass was decreased in cell population but increased in amount of collagen fibers. It is suggested that the testicular descent starts on day 16 together with the commencement of shortening of the gubernacular cord and enlargement of the gubernacular bulb.

Morphologic alterations of the genital mesentery implicated in testis non‐descent in rats prenatally exposed to flutamide

“…However, only the decreased length of the gubernacular ligament ("g") increased the likelihood of testis non‐descent. Normally, the gubernacular ligament undergoes marked elongation before it starts to regress 22,24,25 . The abnormally short gubernacular ligaments found in all flutamide‐exposed testes in our study suggested that flutamide administered in rats during the period the gubernacular elongation takes place (gestational days 16‐17 when day 1 = sperm‐positive day 24 ) inhibits the elongation process.…”

“…Normally, the gubernacular ligament undergoes marked elongation before it starts to regress. 22,24,25 The abnormally short gubernacular ligaments found in all flutamide-exposed testes in our study suggested that flutamide administered in rats during the period the gubernacular elongation takes place (gestational days 16-17 when day 1 = sperm-positive day 24 ) inhibits the elongation process. Moreover, the shortest gubernacular ligaments in association with the undescended testes…”