Ultrastructure of the ileum of Locusta migratoria

Abstract

The epithelium of the ileum of Locusta migratoria is composed of a single layer of columnar cells surrounded on the luminal side by cuticle and on the haemocoel side by a circular muscle layer. Where the circular muscles contact the epithelium, longitudinal muscles are present and the epithelium is slightly reduced. Elsewhere, a subepithelial sinus separates the epithelium from the circular muscle layer. The epithelial cells are characterised by extensive infoldings of the apical and basal cell membranes, which in the latter case, produce a maze of interconnecting channels and spaces. Mitochondria are closely associated with both apical and basal infoldings, although the bulk of these organelles is located in the cytoplasm underlying the infoldings of the apical plasma membrane. Vesicles of assorted sizes occur throughout the cytoplasm. They are particularly abundant in the apical region, where they appear to be produced by pinocytosis. Larger vesicles, containing either material of varying electron density or smaller vesicles, occur in the medial and basal regions of the cells. The contents of some of these vesicles have, in section, a lamellar appearance, composed of concentric layers of material. Similar vesicles are present in the basement membrane as well as the cells and connective tissue of the subepithelial sinus. Microtubules and groups of ribosomes commonly occur throughout the cytoplasm, and lipid-like droplets are also present in some of the cells. Ultrastructural features of the epithelial cells are discussed in relation to current knowledge of the function of the ileum.

Ultrastructure of the hindgut of Drosophila larvae, with special reference to the domains identified by specific gene expression patterns

“…This structure resembles the "apical complex" of the rectal papillae of the termite (Noirot and Noirot-Timothée, 1977) and cockroach (Noirot and Noirot-Timothée, 1976). Similar structures have also been reported in the anterior portion of the hindgut of the termite and Locusta (Yamaoka and Nagatani, 1978;Peacock, 1986). The apical complex is thought to be involved in ATP-dependent ion or water transport.…”

Ultrastructure of the Excretory Organs ofBombus morio(Hymenoptera: Bombini): Bee Without Rectal Pads

“…Vesicles partially filled with electron-dense materials of concentric arrangement, vesicles containing an amorphous particulate material and electron-lucent vesicles were found in the cytoplasm of types I and II cells of the Malpighian tubules of B. morio . We suggest that the interior of these vesicles were fully occupied by spherocrystals, however their content may be lost during histological procedures, resulting in the formation of vesicles with different degrees of spherocrystals dissolution (Berridge & Oschmann, 1969; Bell & Anstee, 1977; Peacock, 1986; Garayoa et al, 1992).…”

“…Type I cells of the ileum of B. morio did not exhibit features of cells involved in absorption, like the small cells in the ileum of L. migratoria (Peacock, 1986). However, well-developed rough endoplasmic reticulum, euchromatic nucleus, and larger vesicles in the apical region suggest that type I cells may play a role in the secretion of protein, as reported for the ant Cephalotes atratus (Bution & Caetano, 2010).…”

K+ absorption by locust gut and inhibition of ileal K+ and water transport by FGLamide allatostatins.

“…This ultrastructure suggests that the colon is not a major site of ion and fluid reabsorption. In contrast, the epithelial cells of the ileum possess extensive apical and basal infoldings that are closely associated with numerous mitochondria, indicative of an epithelium that carries out transport (Peacock, 1986). Using an everted cannulated sac of the locust rectum, Goh and Phillips (Goh and Phillips, 1978) determined that the absorption rate of ions (Na + , Cl − , K + ) and water did not significantly change after the first hour and remained steady for 4 h. The SIET-measured K + fluxes at the ileum utilizing the semi-intact gut preparation showed that these fluxes remained consistent for at least 1.5 h, which was the maximum length of time required to carry out the experiments.…”

“…For instance, developmentally, the foregut arises from ectoderm and is lined by relatively impermeable cuticle, making storage a primary function of this region and absorption difficult (Dow, 1987). The hindgut also originates from ectoderm, but the cuticular lining of the hindgut is far more permeable than the foregut (Maddrell and Gardiner, 1980), allowing this region to carry out ion and water transport (Hanrahan and Phillips, 1983;Peacock, 1985;Peacock, 1986). The epithelial cells of the colon possess short apical microvilli with mitochondria residing at their base but not in close association (Peacock, 1985).…”