Chew Keng Y, Renfree Marilyn B
School of BioSciences, The University of Melbourne, Melbourne, Vic., Australia.
Sex Dev. 2016;10(5-6):301-312. doi: 10.1159/000450927. Epub 2016 Oct 29.
Marsupials are born with undifferentiated gonads, and their reproductive organs differentiate consecutively, not simultaneously as in eutherian mammals. Thus, in the main marsupial model, the tammar wallaby, Macropus eugenii, the testis forms cords 2 days after birth, the ovary develops cortex and medulla about 8 days after birth, the Wolffian duct enlarges from day 10, the prostate begins to form prostatic buds about 25 days after birth, and the phallus does not become sexually dimorphic until after 50 days postpartum (pp). The brain responses also become sexually dimorphic relatively late in development, after day 25 pp. This relatively elongated period of differentiation has allowed experimental manipulation at each stage of development to induce often dramatic sex reversal of both internal and external genitalia.
有袋类动物出生时性腺未分化，其生殖器官是相继分化的，不像有胎盘哺乳动物那样同时分化。因此，在主要的有袋类动物模型——帚尾袋鼩（Macropus eugenii）中，睾丸在出生后2天形成索状结构，卵巢在出生后约8天发育出皮质和髓质，中肾管从第10天开始增大，前列腺在出生后约25天开始形成前列腺芽，而阴茎直到产后50天（pp）后才出现性别二态性。大脑反应在发育过程中也相对较晚出现性别二态性，在产后25天之后。这种相对较长的分化期使得在发育的每个阶段进行实验操作，常常能诱导内外生殖器发生显著的性反转。
