The Cell Science Laboratories, Department of Zoology, University of Western Ontario, London, Ontario, Canada N6A 5B7.
Tissue Cell. 1985;17(6):901-21. doi: 10.1016/0040-8166(85)90045-x.
Epidermal cells in Calpodes and other insects form basal processes or feet that at first extend axially and later shorten at the same time as the larval segment shortens to the pupal shape. The feet grow into spaces at the surfaces of other cells to make a basal interlacing meshwork of cellular extensions that are combined mechanically by their desmosomal attachments to cell bodies above and to the basal lamina below. Microtubules and microfilaments are linked to these junctions by a reticular fibrous matrix. Gap junctions on the feet may couple cells that are several cell bodies removed from one another. The meshwork is also a sieve separating the hemolymph from the spaces between cells to form an intercellular compartment. Entry to the intercellular compartment is through the sieve made by the negatively charged basolateral cell surfaces that can prevent the entry of positively charged molecules such as cationic ferritin. As the cells become columnar, coincident with the metamorphic change in segment shape, the feet shorten and pack more densely together. At this time the basal lamina buckles axially as if responding to contraction of the feet. Segment shape change involves cell rearrangement and relative cell movement, necessitating the transient loss of plasma membrane plaque attachments to the cuticle apically and the loss of junctions laterally. Gap junctions involute in characteristic vacuoles. The metamorphic reduction in cell surface area coincides with the loss of basolateral membrane in smooth tubes and vesicles and the turnover of the apical surface in multivesicular bodies. New apical plasma membrane plaques and new lateral and basal junctions stabilize the cells in their pupal positions.
鳞翅目昆虫及其他昆虫的表皮细胞形成基足，起初沿轴向延伸，随后随着幼虫体节缩短至蛹形，基足同时缩短。这些基足延伸到其他细胞的表面间隙，形成一个基底交织的细胞延伸网络，通过细胞体上方的桥粒连接和下方的基底膜机械结合。微管和微丝通过网状纤维基质与这些连接相连。基足上的间隙连接可以连接彼此相隔几个细胞体的细胞。该网络也是一个筛子，将血液与细胞之间的空间分隔开来，形成细胞外室。进入细胞外室是通过带负电荷的基底外侧细胞表面形成的筛子进行的，这可以防止带正电荷的分子，如阳离子铁蛋白的进入。随着细胞变成柱状，与体节形状的变态变化一致，基足缩短并更加紧密地堆积在一起。此时，基底膜沿轴向弯曲，好像对基足的收缩有反应。体节形状的变化涉及细胞重排和相对细胞运动，需要暂时失去顶端的质膜斑块与角质层的附着以及随后的侧部连接的丧失。间隙连接卷入特征性的空泡中。细胞表面积的变态减少与基底外侧膜在光滑管和小泡中的丧失以及多泡体中顶端表面的周转相吻合。新的顶端质膜斑块和新的侧部和基底部连接稳定了细胞在蛹位的位置。
