Sathananthan A H, Selvaraj K, Trounson A
Institute of Reproduction and Development, Monash Medical Centre, Melbourne, Australia.
Mol Cell Endocrinol. 2000 Mar 30;161(1-2):3-8. doi: 10.1016/s0303-7207(99)00216-6.
Foetal ovarian tissue is now being cultured or frozen, to generate oocytes for assisted reproduction, an emerging technology. This study examines the ultrastructure of oogonia at 13-15 weeks of gestation, which could be used as a control for culture and freezing of foetal ovaries. Oogonia are largely located in the ovarian cortex, whilst primordial germ cells (PGC) and somatic follicle cells compose the surface epithelium. Oogonia and PGC have large vesicular nuclei with clear cytoplasm, compared to dense follicle cells, which have polymorphic nuclei. Follicle cells intermingle with oogonia and establish close contacts - beginning of folliculogenesis. Nuclei of oogonia contain one to three highly reticulated nucleoli, reflecting high levels of RNA synthesis at the onset of growth. Rough endoplasmic reticulum (RER) form stacks of cisternae associated with numerous ribosomes. Prominent organelles in the ooplasm are elongated mitochondria with dense matrices and tubular cristate presenting a multilocular appearance. Typical Golgi complexes, dense bodies and clear vacuoles are present and microfilaments are located beneath the plasma membrane. The most remarkable feature of oogonia is that they have typical juxtanuclear centrioles (diplosomes) with dense pericentriolar material, which nucleate microtubules, characteristic of functional centrosomes organizing the cytoskeleton. The mature oocyte has no centrioles, since the maternal centrosome is inactivated or reduced, while the paternal is dominant. Centrioles are most likely involved in mitosis of oogonia.
胎儿卵巢组织目前正在进行培养或冷冻，以生成用于辅助生殖的卵母细胞，这是一项新兴技术。本研究检查了妊娠13 - 15周时卵原细胞的超微结构，其可作为胎儿卵巢培养和冷冻的对照。卵原细胞主要位于卵巢皮质，而原始生殖细胞（PGC）和体细胞卵泡细胞构成表面上皮。与具有多形核的致密卵泡细胞相比，卵原细胞和PGC具有大的泡状核和清晰的细胞质。卵泡细胞与卵原细胞相互交织并建立紧密联系——卵泡发生的开始。卵原细胞核含有一到三个高度网状的核仁，反映了生长开始时高水平的RNA合成。粗面内质网（RER）形成与众多核糖体相关的扁平囊泡堆叠。卵质中的显著细胞器是具有致密基质和管状嵴的细长线粒体，呈现多泡状外观。存在典型的高尔基体复合体、致密体和透明液泡，微丝位于质膜下方。卵原细胞最显著的特征是它们具有典型的近核中心粒（双体），周围有致密的中心粒周物质，这些物质使微管成核，是组织细胞骨架的功能性中心体的特征。成熟卵母细胞没有中心粒，因为母本中心体失活或减少，而父本中心体占主导。中心粒很可能参与卵原细胞的有丝分裂。
