无尾两栖类性腺发育研究进展

脊椎动物的性腺发育一直是生物学领域研究的热点,无尾两栖动物因其胚胎发育的独立性和易观察性而成为发育生物学研究领域的良好材料,并取得了许多成果。本文综述了无尾两栖类原始性腺形成、性腺分化、精巢和卵巢的发育,以及配子发生等方面的研究进展。无尾两栖类原始性腺形成主要发生在鳃盖褶和后肢芽形成时期,不同物种略有不同;性腺分化通常以卵原细胞或卵巢腔出现为标志,但对于部分具有初级性腔的物种并不适用;精巢内支持细胞包围精原细胞形成生精囊,囊内细胞经过一系列事件最终排出精子;卵巢由于卵母细胞发育最终卵巢腔消失,卵母细胞在卵泡内不连续分裂,最后形成卵细胞。无尾两栖动物的性腺发育过程具有一定相似性,但不同物种之间存在差异。

Gonadal Development in Anuran Amphians

The development of vertebrate gonads has been extensively investigated. Anuran amphibians are good animal models in the field of developmental biology because of their embryonic development independence and observabilit. In this paper, we review the research progress on primitive gonad formation, gonadal differentiation and development of testis and ovary, as well as gametogenesis in anuran amphibians. Primitive gonad formation in anuran amphibians occurs mainly during the periods of gill cover fold and hindlimb bud formation, and that different species show slight difference. Gonadal differentiation is usually marked by the presence of oogonias or ovarian cavities, but not for some species with primary sex cavities. Support cells surround the spermatogonia to form a seminal vesicle, and the cells in the vesicle undergo a series of activities to finally discharge the sperm. Ovary is formed eventually, due to the the oocyte development and disappearance of ovarian cavity, and the oocyte divides discontinuously within the follicle and finally form egg cells. The gonadal developmental processes in anuran amphibians are similar, but also show differences between species.