Chlamydia isopodii sp. n., an obligate intracellular parasite of Porcellio scaber.

In an ultrastructural study of the hepatopancreas of Porcellio scaber, an obligate intracellular parasite, Chlamydia, was noted in the epithelial cells. Although the infection was found to extend the entire length of the hepatopancreas, it was most extensive in the glandular region. Indirect immunofluorescence testing revealed no cross-reactivity with either lymphogranuloma venereum or psittacosis antisera.

An investigation of the presence of smooth endoplasmic reticulum and GERL during vitellogenesis in the ovary of Drosophila melanogaster.

The presence of a type of smooth endoplasmic reticulum often associated with the Golgi-endoplasmic reticulum-lysosome complex (GERL) is demonstrated in the cortical region of the nurse cells located in the vitellarium of the Drosophila melanogaster ovary. This proliferation of smooth endoplasmic reticulum/GERL-like structures appears to be restricted to the area of the nurse cells that are actually involved in endocytosis in the region of adjacent, non-vitelline membrane-forming follicle cells. Smooth surface vesicles are also found in conjunction with rough endoplasmic reticulum in a close-fitting arrangement enclosing follicle and nurse cell lipid vesicles suggesting an association of GERL with secretory body formation and lipid metabolism. Autophagic vacuoles (type 2) are observed near the 'trans' aspect of the Golgi while residual bodies are noted to be more distal to this region. The relationship of observed ultrastructural similarities during the oogenesis of an insect to previously established findings of GERL in a variety of mammalian cell types is discussed.

Fine structure of the digestive tract epithelium in the terrestrial isopod. Armadillidium vulgare.

An ultrastructural study of the hindgut, associated hepatopancreatic lobes and hepatopancreatic ducts of the terrestrial isopod, Armadillidium vulgre was undertaken. The simple epithelium which lines the heptopancreas consists of two cell types, S and B. Both cell types have numerous microvilli. A simple epithelium consisting of one cell type lines the hepatopancreatic ducts and the hindgut. Microvilli are not evident in the duct. The cells of the duct and the hindgut are covered with a cuticle. Dense granular bodies are characteristic of the cytoplasm of the duct cells. The hindgut epithelial cells have pronounced apical and basal-lateral cytoplasmic infoldings. Apical infoldings from large subcuticular spaces, especially in the posterior hindgut. Microtubules and large numbers of mitochondria are associated with the cytoplasmic infoldings. Large microtubular bundles are seen in the peripheral cytoplasm, and residual bodies are present in the central cytoplasm. Lateral plasma membranes form septate desmosomes in the apical region of cells, while zonulae adherentes and intercellular spaces are found basal to the septate desmosomes. The cellular organization of the hindgut is suggestive of cells active in water and ion transport.

The fine structure of the hepatopancreas of the woodlouse, Oniscus ascellus.

The present ultrastructural study of the hepatopancreas of Oniscus ascellus would seem to indicate that the entire gland functions as a true midgut and is involved in absorption and secretion. Two differentiated cell types, the S and B, are present throughout the gland except for a small area of the posterior or regenerative zone. Ultrastructural features that have been associated with absorption include the presence of a surface enteric coat, regularity of microvillar core filaments, an organelle free region under the microvilli and the uniform distribution of mitochondria below this area. These features are present in both the S and B cell types. Features that are typical of secretory cells include the presence of extensive arrays of parallel rough endoplasmic reticulum, the very active dictyosomes with dilated cisternae and large secretory bodies. These features are present in the B cell. Although occasional arrays of parallel endoplasmic reticulum were noted in the S cell, active dictyosomes with dilated cisternae were not evident. From this ultrastructural study it would appear that the B cell functions in absorption and secretion, while the S cell functions primarily in absorption. A cytochemical study is now in progress.