蓖麻蚕蛹脏器脂肪体的细胞超微构造

ULTRASTRUCTURE OF THE ADIPOCYTES OF PUPAL PERIVISCERAL FAT-BODY IN PHILOSAMIA CYNTHIA

本文用电子显微镜和光学显微镜观察蓖麻蚕(Philosamia cymthia)蛹脏器脂肪体的细胞构造特征。脂肪细胞在整个蛹期含有大量的脂肪滴和蛋白质颗粒,但只在蛹前期含有较多的糖原颗粒及相当数量的线粒体与粗面内质网,并有多泡体的形成。在蛹中期脂肪细胞内的自噬体明显增多,内质网消失。无脑蛹的脂肪细胞近似蛹后期脂肪细胞的构造。

The ultrastructure of the adipocytes of perivisderal fat-body in Philosamia pupae was studied with light and electron microscopy. The perivisceral fat-body mainly consisted of two types of cells: adipocytes and urocytes. The adipocytes constituted the major part of the fat-body. Oenocytes were also found in the fat-body.During the early stage of pupal development (day 1-3 pupae), the adipocyte contained a large amount of lipid droplets bounded with discernible membrane, light or deep electrondense protein granules and a number of glycogen granules. Within the scarce cytoplasm, some mitochondria and rough endoplasmic reticula (rER) were scattered. Formation of multi-vesicular bodies and outflow of nuclear materials via the nuclear pores were observed. Autophagosomes were present but few in number.At the middle stage of pupal development (day 4—10 pupae), the adipocyte underwent conspicuous changes. The membranes that confined the lipid droplets became disintegrated and protein granules degenerated, brokedown or invaded by peroxisomes. Glycogen granules and rER disappeared. Mitochondria degencrated and decreased in number while autophagosomes increased. These phenomena persisted in later stage till adult development.Investigation on the ultrastructure of the adipocytes in debrained pupae revealed that most organelles degenerated and numerous zymosomes, peroxisomes and autophagosomes were present.