Cioffi M
Tissue Cell. 1979;11(3):467-79. doi: 10.1016/0040-8166(79)90057-0.
Light and electron microscopic examination of the midgut of Manduca sexta has shown that the organization of this tissue is more complex than was originally believed. The midgut can be divided into anterior, middle and posterior regions on the basis of the pattern of folding of the epithelial sheet, and variations in the structure of goblet and columnar cells which occur along its length. The columnar cells show gradual structural changes form the anterior to the posterior end of the midgut. For example, the microvilli in the anterior region form a dense, interconnecting network from which vesicles break off. This organization becomes less obvious through the middle region, until by the posterior region each microvillus is unconnected to adjacent microvilli along its entire length and vesicles are no longer produced. Two distinct types of goblet cells are found. In the anterior and middle regions the goblet cells have a large basally located cavity, but in the posterior region the cavity occupies only the apical half of the cell. In both cases the cavity is formed by invagination of the apical membrane, which is studded with small particles implicated in active ion transport. In the anterior and middle regions this membrane is closely associated with mitochondria, but not in the posterior region. The significance of the observed structural differences is discussed in relation to active ion transport.
对烟草天蛾中肠进行的光学显微镜和电子显微镜检查表明，该组织的结构比最初认为的更为复杂。根据上皮层的折叠模式以及沿中肠长度分布的杯状细胞和柱状细胞结构的变化，中肠可分为前部、中部和后部区域。柱状细胞从中肠前端到后端呈现出逐渐的结构变化。例如，前部区域的微绒毛形成一个密集的、相互连接的网络，囊泡从中脱离。这种结构在中部区域变得不那么明显，直到后部区域，每个微绒毛在其整个长度上都与相邻微绒毛不相连，并且不再产生囊泡。发现了两种不同类型的杯状细胞。在前部和中部区域，杯状细胞有一个位于基部的大腔，但在后部区域，腔仅占据细胞顶端的一半。两种情况下，腔都是由顶端膜内陷形成的，顶端膜上布满了与主动离子运输有关的小颗粒。在前部和中部区域，该膜与线粒体紧密相关，但在后部区域则不然。结合主动离子运输对观察到的结构差异的意义进行了讨论。
