Müllerian inhibiting substance production and testicular migration and descent in the pouch young of a marsupial.
Müllerian inhibiting substance production and testicular migration and descent in the pouch young of a marsupial.
复制标题
苗勒氏管抑制有袋动物幼崽育儿袋中的物质产生和睾丸迁移和下降。
作者：
J. Hutson;G. Shaw;W. O;R. Short;M. Renfree
利用小鼠胎儿泌尿生殖嵴的器官培养生物测定法，在育儿袋生活期间确定了一种澳大利亚有袋动物——尤金袋鼠（Macropus eugenii）发育中的睾丸产生苗勒氏管抑制物质（MIS）的个体发生过程。这一信息与睾丸迁移和下降过程中的形态学事件相关。在2至85日龄的育儿袋幼崽的睾丸（而非卵巢或肝脏）中发现了MIS生物活性。MIS的产生在第2天就已开始，这是在睾丸分化的最初大体形态学迹象出现后的一天内。苗勒氏管退化发生在10至30天之间，这部分与睾丸向腹股沟区迁移以及引带球增大（15至30天）相吻合。这些观察结果与MIS可能参与睾丸经腹腔迁移的假说相符。只有在睾丸通过腹股沟环下降之后，附睾才开始发育和生长。这并不支持附睾参与睾丸下降到阴囊的观点。袋鼠睾丸后性分化的基本事件顺序与真兽亚纲哺乳动物的情况足够相似，使其成为未来研究睾丸分化、迁移和下降的极佳实验模型。
The ontogeny of Müllerian inhibiting substance (MIS) production by the developing testis of an Australian marsupial, the tammar wallaby (Macropus eugenii), was determined during pouch life using an organ-culture bioassay of mouse fetal urogenital ridge. This information was related to the morphological events during testicular migration and descent. MIS biological activity was found in testes (but not ovaries or liver) of pouch young from 2 to 85 days of age. MIS production had commenced by day 2, which is within a day of the first gross morphological signs of testicular differentiation. Müllerian duct regression occurred between 10 and 30 days, which partly coincided with testicular migration to the inguinal region and enlargement of the gubernacular bulb (15 to 30 days). These observations are consistent with the hypothesis that MIS may be involved in testicular transabdominal migration. The epididymis commenced development and growth only after the testis had descended through the inguinal ring. This provides no support for the suggestion that the epididymis is involved in testicular descent into the scrotum. The basic sequence of events in post-testicular sexual differentiation in the wallaby is sufficiently similar to that seen in eutherian mammals to make it an excellent experimental model for future studies of testicular differentiation, migration and descent.