The trophotaenial placenta of a viviparous goodeid fish. I. Ultrastructure of the internal ovarian epithelium, the maternal component
The trophotaenial placenta of a viviparous goodeid fish. I. Ultrastructure of the internal ovarian epithelium, the maternal component
复制标题
胎生古德鱼的滋养层胎盘。
作者：
J. Lombardi;J. P. Wourms
古德鱼的胚胎在卵巢腔内发育至足月，由于母体营养物质通过营养胎盘的转移，它们的体重显着增加。胎盘由胚胎成分（滋养层）和母体成分（卵巢内膜）组成。通过透射电子显微镜、扫描电子显微镜和光学显微镜对胎生古德鱼 Ameca splendens 的妊娠和非妊娠卵巢进行了检查。芨芨草的单个正中卵巢是一个中空结构，其腔被高度折叠的纵向卵巢隔膜分成侧室。生发组织发生在卵巢内壁的褶皱内，延伸到两个侧室中的每一个。母体营养型胚胎发育发生在卵巢室内。在妊娠期间，卵巢管腔内壁与发育中胚胎的体表和滋养层上皮直接并置。卵巢内膜由一个简单的立方形上皮组成，称为内部卵巢上皮（IOE），覆盖在血管化良好的结缔组织床上。 IOE 的细胞顶部凸出。发育良好的颗粒状和无颗粒状内质网和大量具有电子致密内容的大膜结合囊泡占据了 IOE 细胞的顶端细胞质。 IOE 内区分同一细胞类型的两种功能状态。 I 期细胞含有很少（如果有的话）位于顶部的大囊泡； II期细胞包含许多。 IOE 的分泌产物被认为是胚胎发育的重要营养来源。结合母体胚胎营养转移过程讨论了 IOE 与发育胚胎滋养层上皮的结构和功能关系。
Embryos of goodeid fishes develop to term within the ovarian lumen, where they undergo considerable increase in weight due to transfer of maternal nutrients across a trophotaenial placenta. The placenta consists of an embryonic component, the trophotaeniae, and a maternal component, the ovarian lining. The latter was examined by transmission electron microscopy, scanning electron microscopy, and light microscopy in both gravid and non‐gravid ovaries of the viviparous goodeid fish, Ameca splendens. The single median ovary of A. splendens is a hollow structure whose lumen is divided into lateral chambers by a highly folded longitudinal ovarian septum. Germinal tissue occurs within folds of the ovarian lining that extend into each of the two lateral chambers. Matrotrophic embryonic development takes place within ovarian chambers. During gestation, the lining of the ovarian lumen is in direct apposition to body surfaces and trophotaenial epithelia of developing embryos. The ovarian lining consists of a simple cuboidal epithelium, termed the internal ovarian epithelium (IOE), overlying a well‐vascularized bed of connective tissue. Cells of the IOE are apically convex. Well‐developed granular and agranular endoplasmic reticula and numerous large membrane‐bound vesicles with electron‐dense content occupy the apical cytoplasm of IOE cells. Two functional states of the same cell type are distinguished within the IOE. Phase I cells contain few, if any, large apically situated vesicles; Phase II cells contain many. Secretory products of the IOE are presumed to be an important source of nutrients for embryonic development. Structural and functional relationships of the IOE to the trophotaenial epithelium of developing embryos are discussed in relation to maternal‐embryonic nutrient transfer processes.