Mate K E
Cooperative Research Centre for Conservation and Management of Marsupials, School of Biological Sciences, Macquarie University, New South Wales, Australia.
Anim Reprod Sci. 1998 Oct;53(1-4):237-52. doi: 10.1016/s0378-4320(98)00116-x.
The zona pellucida (ZP) is an extracellular coat that surrounds the mammalian egg, and serves as the primary recognition site for fertilizing spermatozoa. The timetable of ZP formation was examined in two marsupials, the tammar wallaby (Macropus eugenii) and the brushtail possum (Trichosurus vulpecula) using conventional histological methods, immunofluorescence and electron microscopy. Ovaries from tammar wallaby pouch young less than 80 days of age contained only primordial follicles with a single layer of flattened granulosa cells. There was no evidence of ZP formation until 98 days, when a small number of eggs surrounded by a single layer of cuboidal granulosa cells had a ZP detectable by periodic-acid-schiff staining and rabbit anti-pig ZP polyclonal antibody labelling. Possum ovaries at 108 and 114 days also contained a small number of eggs with a ZP and a single layer of cuboidal granulosa cells. The antibody also labelled the peripheral cytoplasm of oocytes at this stage and, occasionally, the granulosa cells. Antral follicles were first detected at 144 days in the wallaby and 125 days in the possum, and always contained an egg surrounded by a ZP. Ovaries from 147, 158, 165, 181, 184 and 210-day-old tammar wallabies contained a range of follicle types from primordial through early antrum formation. Electron microscopy confirmed observations made at the light microscope level. The ZP was first detectable in small primary follicles with a single layer of cuboidal granulosa cells in areas where microvilli had begun to form on the egg plasma membrane. Immunogold labelling indicated the egg cytoplasm as the origin of the ZP proteins. The ZP completely filled the space between the egg and the adjacent granulosa cells in preantral follicles, so that there was no perivitelline space.
透明带（ZP）是一种围绕哺乳动物卵子的细胞外被，是精子受精的主要识别位点。利用传统组织学方法、免疫荧光和电子显微镜，研究了两种有袋动物——帚尾袋鼩（Trichosurus vulpecula）和短尾矮袋鼠（Macropus eugenii）中ZP形成的时间表。小于80日龄的短尾矮袋鼠育儿袋幼崽的卵巢中仅含有原始卵泡，其颗粒细胞为单层扁平细胞。直到98日龄才有ZP形成的迹象，此时少数被单层立方形颗粒细胞包围的卵子，通过高碘酸希夫染色和兔抗猪ZP多克隆抗体标记可检测到ZP。108日龄和114日龄的帚尾袋鼩卵巢中也含有少数带有ZP和单层立方形颗粒细胞的卵子。该抗体在此阶段也标记了卵母细胞的周边细胞质，偶尔也标记颗粒细胞。在短尾矮袋鼠中，144日龄首次检测到有腔卵泡，在帚尾袋鼩中为125日龄，且总是含有被ZP包围的卵子。147、158、165、181、184和210日龄的短尾矮袋鼠卵巢含有一系列从原始卵泡到早期有腔卵泡形成阶段的卵泡类型。电子显微镜证实了光学显微镜水平的观察结果。在卵子质膜上开始形成微绒毛的区域，单层立方形颗粒细胞的小初级卵泡中首次可检测到ZP。免疫金标记表明卵细胞质是ZP蛋白的起源。在窦前卵泡中，ZP完全填充了卵子与相邻颗粒细胞之间的空间，因此没有卵周间隙。
