花背蟾蜍蝌蚪皮肤在类坏死条件下超微结构的变化~*

已知发生类坏死的无尾两栖类蝌蚪皮肤,可加速被眼诱导为角膜的进程。采用弱酸(0.01N醋酸)和弱碱(0.001N氨水)处理花背蟾蜍蝌蚪皮肤使之发生类坏死,对比观察了正常和发生类坏死皮肤的超微结构,结果发现皮肤在类坏死条件下发生下列变化:(1)表皮细胞内的张力原纤维显得疏松,有变粗及聚集的现象,弱酸处理者更明显;(2)表皮细胞中细胞器减少,细胞质内出现大量液泡;相邻细胞的细胞间隙变狭窄;(3)表皮细胞核内的染色质分布不均匀,浓缩为较大的团块,使核内出现不规则的空隙;(4)基膜中胶原纤维明暗相间的条纹结构较模糊。文中对类坏死条件下皮肤超微结构的变化和加速角膜诱导进程间的可能关系进行了讨论。

ULTRASTRUCTURAL CHANGES IN SKIN OF TOAD (BUFO RADDEI) TADPOLE UNDER THE CONDITIONS OF PARANECROSIS

Previous studies had shown thatwhen the paranecrotic skin of thetadpole was transplanted to the positionof the excised cornea of a tadpole atthe same stage,this piece of skin wastransformed into a new cornea muchmore rapidly than the intact one. In this paper the authors made anattempt to compare the ultrastructuresof normal tadpole skin with that ofparanecrotic skin caused by low con-centration of acetic acid(0.01N)andof ammonia water(0.001N).Certainultrastructural changes in the skin underthe conditions of paranecrosis are foundas follows: (1)The tonofilaments in the ehider-mal cells become more or less aggre-gated and appeared loosened.Thesechanges are more obvious in the skin ofweak acid treatment. (2) The organelles in epidermal cellsare decreased in quantity,numerousvacuoles are observed in the cytoplasm;the intercellular spaces between adja-cent cells have become narrowed thanthe normal. (3)The chromatin granules arefound in condensed clumps scatteredunevenly throughout the nucleus,lea-ving irregular spaces in the nucleus. (4)The dark and light periodicbands of the collagenous fibres in thebasement membrane are obscure incontours. The changes mentioned above arediscussed in relation to the possiblemechanisms of quickening the processof corneal induction under the conditions of skin paranecrosis.