ULTRASTRUCTURE OF THE INTESTINAL EPITHELIUM, LUMEN, AND ASSOCIATED BACTERIA IN HETERORHABDITIS-BACTERIOPHORA

Heterorhabditis bacteriophora is an obligate parasite of insects that contains the bacterial symbiont, Xenorhabdus luminescens, in its intestinal lumen. Ultrastructural observations were made of the intestinal epithelium, lumen, and associated bacteria. The oligocytous intestine of the infective juvenile of H. bacteriophora has junctional complexes that delineate the boundaries of cells forming the intestinal lumen. Fine structure of the intestinal cells includes microvilli on the apical membranes bordered by a dense matrix of vesicular endoplasmic reticulum and accumulations of variably stained electron-dense granules within each cell. Rod-shaped granules within each cell. Rod-shaped bacterial cells occur singly or en masse in the lumen of the intestine. Some bacteria appear to undergo autolysis or show interaction with the lumen contents.