Extracellular shedding of photoreceptor membrane in the open rhabdom of a tipulid fly
Extracellular shedding of photoreceptor membrane in the open rhabdom of a tipulid fly
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毛蝇开放横杆中光感受器膜的细胞外脱落
DOI：
10.1007/bf00232283
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发表时间：
2004
影响因子：
3.6
通讯作者：
A. D. Blest
中科院分区：
文献类型：
--
作者：
David S. Williams;A. D. Blest
摘要澳大利亚斑潜蝇Ptilogyna的复眼在更替过程中将其横纹膜的大部分脱落到细胞外空间。视网膜的横纹位于一个共同的细胞外空间(ECS)，该空间在视网膜近端细分。黎明前，每个横纹肌的微绒毛的远端区域分化，并在常规固定后变得不那么电子密度。然后，分化的区域扩张并形成不规则的轮廓。黎明后的几个小时，转化的尖端断裂，在ECS形成碎屑。降解的膜通过大量的内吞作用内化回到视网膜细胞中。视网膜在与内皮细胞相邻的部位形成伪足，吞噬膜碎屑，首先位于受体细胞内的空泡中，然后形成非常大的多囊泡体。后者转变为多层和残余体，推测是裂解的。围绕这些次级溶酶体的是粗面内质网和光滑的管状系统，在比较的基础上初步认为它们可以提供水解酶。关于复眼超微结构的文献提供了少量的例子，可以怀疑细胞外脱落是由于形态原因。请注意与脊椎动物视网膜中光感受器膜脱落的类比。
SummaryThe compound eyes of the Australian tipulid fly, Ptilogyna, shed the bulk of their rhabdomeral membrane to extracellular space during turnover. The rhabdomeres of the retinulae lie in a common extracellular space (ECS), which is subdivided in the proximal retina. Before dawn, a distal region of the microvilli in each rhabdomere differentiates and becomes less electron-dense after conventional fixation. The differentiated region then dilates and develops an irregular profile. A few hours after dawn, the transformed tips break off and form a detritus in the ECS. The degraded membrane is internalised back into the retinula cells by mass endocytosis. Retinulae develop pseudopodia at sites bordering the ECS and engulf the membrane detritus, which comes to lie first of all in vacuoles within the receptor cells and then forms very large multivesicular bodies. The latter transform to multilamellar and residual bodies and are, presumably, lysed. Surrounding these secondary lysosomes are rough endoplasmic reticulum and smooth tubular systems, tentatively considered on comparative grounds to provide hydrolases. The literature concerning the ultrastructure of compound eyes offers a small number of instances where extracellular shedding can be suspected for morphological reasons. Attention is drawn to analogies with the shedding of photoreceptor membranes in vertebrate retinae.