THE ORIGIN OF THE NASCENT BLASTOCOELE IN PREIMPLANTATION MOUSE EMBRYOS - ULTRASTRUCTURAL CYTOCHEMISTRY AND EFFECT OF CHLOROQUINE
THE ORIGIN OF THE NASCENT BLASTOCOELE IN PREIMPLANTATION MOUSE EMBRYOS - ULTRASTRUCTURAL CYTOCHEMISTRY AND EFFECT OF CHLOROQUINE
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DOI：
10.1007/bf00637187
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发表时间：
1991-01-01
期刊：
影响因子：
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通讯作者：
ALEXANDRE, H
中科院分区：
文献类型：
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作者：
AZIZ, M;ALEXANDRE, H
已知小鼠桑椹胚在一些外部细胞进入第六个细胞周期后立即发生空化（Garbutt等人，1987）。由于早期细胞学特征的空化仍然不清楚，我们进行了仔细的超微结构分析晚期桑椹胚初生囊胚。此外，由于溶酶体的成熟可能参与腔形成的第一步，我们把注意力集中在这些细胞器的三偏磷酸酶活性的细胞化学定位和氯喹对precavitation胚胎的影响的研究。我们的研究结果表明，空化开始在一些外部细胞（大概是主管细胞进入第六个细胞周期），由氯喹敏感的形成的降解性自噬泡吞噬脂滴和空泡含有嗜锇物质。这些复杂的结构扩大（由于脂质代谢？）并因此转化成胚泡内空腔，其通过膜融合过程非常迅速地变成细胞外空腔并结合。胚泡的胚外极就是这样确定的。此外，我们认为，覆盖内细胞团（ICM）细胞的胞质突起（已知其在早期空化期间限制其全能性的表达）（Fleming et al. 1984）是生长中的胚泡内腔壁的最新残留物。
Mouse morulae are known to undergo cavitation as soon as some external cells have entered the sixth cell cycle (Garbutt et al. 1987). Since the early cytological features of cavitation are still unclear, we undertook a careful ultrastructural analysis of late morulae-nascent blastocysts. In addition, since maturation of lysosomes might be involved in the first step o cavity formation, we focused our attention on these organelles by means of the cytochemical localization of trimetaphosphatase activity and by the study of the effects of chloroquine on precavitation embryos. Our results suggest that cavitation starts in a few external cells (presumably competent cells entering the sixth cell cycle), by the chloroquine-sensitive formation of degradative autophagic vacuoles engulfing lipid droplets and vacuoles containing osmiophilic material. These complex structures enlarge (as a result of lipid metabolism?) and so transform into intrablastomeric cavities which, by means of a membrane fusion process, very rapidly become extracellular cavities that coalesce. The abembryonic pole of the blastocyst is determined in this way. Moreover, we suggest that the juxtacoelic cytoplasmic processes covering the inner cell mass (ICM) cells, which are known to restrict the expression of their totipotency during early cavitation (Fleming et al. 1984), are the latest remnants of the walls of the growing intrablastomeric cavities.