Butterworth F M, Emerson L, Rasch E M
Department of Biological Sciences, Oakland University, Rochester, MI 48309.
Tissue Cell. 1988;20(2):255-68. doi: 10.1016/0040-8166(88)90047-x.
Using morphometric and cytochemical techniques we have described changes taking place in the fat body cells during three different stages of development. The cell number remains constant at about 2200 cells during larval life and then decreases gradually and continuously throughout metamorphosis and the first 3 days of the adult stage until no more cells can be observed. Cell size increases rapidly during the larval period and decreases steadily during metamorphosis and adult stage. The size of the nuclei increases during the larval instars and decreases during the pupal interval. The change in nuclear size is correlated with the amount of DNA present throughout development implying the nuclear DNA is synthesized during the larval period and degraded gradually during metamorphosis. The cell size changes are due in large part to accumulation or loss of reserve substances: lipid droplets, glycogen deposits and protein granules. During metamorphosis the amount of lipid decreases slightly whereas glycogen experiences two loss cycles. The protein granules in the form of lysosomes continue to increase in amount during the first day of metamorphosis because of a short period of massive autophagy. Then the lysosomes decrease in amount throughout the remainder of metamorphosis. The lysosomes stain positively for lipofuscin.
我们运用形态测量和细胞化学技术，描述了脂肪体细胞在三个不同发育阶段所发生的变化。在幼虫期，细胞数量保持恒定，约为2200个细胞，然后在整个变态发育过程以及成虫期的前3天逐渐持续减少，直至无法观察到更多细胞。幼虫期细胞大小迅速增加，在变态发育和成虫期则稳步减小。幼虫龄期细胞核大小增加，蛹期细胞核大小减小。细胞核大小的变化与整个发育过程中DNA的含量相关，这意味着核DNA在幼虫期合成，并在变态发育过程中逐渐降解。细胞大小的变化在很大程度上归因于储备物质的积累或损失：脂滴、糖原沉积物和蛋白质颗粒。在变态发育过程中，脂质含量略有下降，而糖原经历两个损失周期。由于短时间的大量自噬作用，以溶酶体形式存在的蛋白质颗粒在变态发育的第一天数量持续增加。然后，在变态发育的剩余阶段，溶酶体数量减少。溶酶体对脂褐素呈阳性染色。
