Shackell G H, Norman N G, McLeod B J, Hurst P R
AgResearch Invermay, Mosgiel, New Zealand.
Anat Rec. 1996 Oct;246(2):224-30. doi: 10.1002/(SICI)1097-0185(199610)246:2<224::AID-AR9>3.0.CO;2-0.
Although the pattern of gonadal differentiation in marsupials is well documented, there is little information available on germ cell initiation and development. Furthermore, neither parameter has been well described for the brushtail possum (Trichosurus vulpecula).
A quantitative study of ovarian germ cell proliferation and the onset of folliculogenesis was undertaken in pouch young of the brushtail possum. Pouch-young age was estimated from measurements of head length and crown-rump length. Estimates of total ovary volume, the number of primary and meiotic germ cells, and the numbers of primordial follicles were made by using Cavalieri's principle and the optical disector. In addition, the age at which follicle growth began was determined.
The estimated ages of the pouch young in the study ranged from 26 to 207 days postpartum. Body weight, ovary weight, and ovary volume were all highly correlated with estimated age. Germ cell meiotic activity was well established by day (d) 26 of pouch life. Germ cell numbers reached a maximum (691 x 10(3)/ovary) at d67 postpartum and then declined with increasing age. Primordial follicles were first evident at d67. Primary follicles were first seen at d97, secondary follicles at d105, and antral follicles at d155.
This first quantitative study of ovarian follicle development in the female pouch young of the brushtail possum provides a basis for the temporal definition of ovarian maturation in this marsupial species. The pattern of germ cell proliferation and development is similar to that seen in eutharian mammals.
虽然有袋类动物性腺分化模式已有充分记录，但关于生殖细胞起始和发育的信息却很少。此外，帚尾袋貂（Trichosurus vulpecula）的这两个参数都没有得到很好的描述。
对帚尾袋貂育儿袋幼崽的卵巢生殖细胞增殖和卵泡发生起始进行了定量研究。通过测量头长和冠臀长来估算育儿袋幼崽的年龄。利用卡瓦列里原理和光学分割器对卵巢总体积、初级和减数分裂生殖细胞数量以及原始卵泡数量进行估算。此外，还确定了卵泡开始生长的年龄。
研究中育儿袋幼崽的估计年龄范围为产后26至207天。体重、卵巢重量和卵巢体积均与估计年龄高度相关。在育儿袋生活第26天，生殖细胞减数分裂活动已充分确立。生殖细胞数量在产后第67天达到最大值（691×10³/卵巢），然后随着年龄增长而下降。原始卵泡在第67天首次出现。初级卵泡在第97天首次出现，次级卵泡在第105天出现，窦状卵泡在第155天出现。
这项对帚尾袋貂雌性育儿袋幼崽卵巢卵泡发育的首次定量研究为该有袋类物种卵巢成熟的时间定义提供了依据。生殖细胞增殖和发育模式与真兽类哺乳动物相似。
