扬子鳄胚胎中肾发生及退化

Development and degeneration of mesonephros in Alligator sinensis embryos

目的:在11个不同发育时期扬子鳄胚胎中观察中肾的发生及退化过程。方法:采用电镜、细胞化学及免疫组织化学方法。结果:孵育第6期在中肾管前端附近出现一些中肾小泡。第8期形成“S”形中肾小管。第13～17期鳄胚体前部部分中肾小管盲端内陷,形成原始的肾小囊和肾血管球,中肾小管显著伸长并迂回曲折。第20～22期,体前后部中肾组织均已形成完整的肾单位。中肾小管颈段由纤毛柱状上皮细胞组成,近球小管上皮细胞含丰富的PAS阳性物质并呈表皮生长因子(EGF)、转化生长因子(TGFβ_1)和生长抑素(SS)免疫阳性反应。第24～28期,体前部至后部的中肾组织依次退化。结论:(1)扬子鳄中肾除重吸收作用外还具有内分泌功能;(2)中肾退化时,细胞凋亡依次表现为核固缩,出现大量凋亡小体,线粒体数目剧增并膨胀,线粒体等细胞器自溶及核消失;(3)中肾退化可能与小管细胞中TGFβ_1及SS大量表达有关。

Objective:To investigate the development and degenration of mesonephros in Alligator sinensis embryos at 11 different incubation stages. Methods:Electromicroscopic,cytocriemical and irnmunohistochernical methods were applied. Results:Some mesonephric vesicles appeared in the vicinity of the anterior of the mesonephric ducts at 6th stage. At 8th stage S-shaped mesonephric tubules took shape. During 13rd-17th stages a part of mesonephric tubuli in the anterior of the embryos invaginated at its blind ends, resulting in primitive renal sacs and glomerulus and mesonephric tubuli elongated distinctly and curved back and forth. All mesonephric tissue had produced integrated nephric units during 20th-22nd stages. The neck part of tubuli was covered with ciliated epithelial cells. The epithelial cells of proximal tubuli contained abound-ant PAS-positive substances and appeared epidermal growth factor(EGF), transforming growth factor pi (TGF Pi), so-matostatin immunoreaction. During 24th-28th stages mesonephric tissue from anterior to posterior of the embryos degen-eratd in turn. Conclusion: (1)Mesonephros of Alligator sinensis embryo,besides reabsortion,also has the function of endocrine. (2)While mesonephros degenerating,apoptosis takes place with following characteristics:nuclear condensation,appearance of many apoptosis bodies, rapid increase in the number and expending of mitochondria, self-decay of cell organs such as mitochondria and disappearance of nuclei. (3)Degeneration of mesonephros might be related with the excessive expression of TGF (3) and somatostain.