Histochemistry and fine structure of the bladder tegument of a larval Multiceps endothoracicus.

Certain differences were found in the histochemistry and fine structure of an active bladder tegument of an infective larva of M. endothoracicus and a regressively changing bladder of an aging larva of this species. The bladder tegument of an aging larva contained an accumulation of acid mucosubstances and phospholipids, that of a younger larva neutral mucosubstances, and it reacted less strongly than the former to tyrosine, cystine and tryptophane. Evidence was obtained with the scanning (SEM) and transmission (TEM) microscope for regressive changes in the bladder of an aging larva: its microtriches were more slender, less tightly packed and fibrously interconnected, and there were spherical formations adhering to the microthrix border. Sometimes, the vacuolation of rod-shaped bodies was so much advanced that these bodies looked like vacuoles arising to the surface of the distal cytoplasm. Another sign of bladder regression was the formation of vacuoles in the cytoplasm of subtegumental cells with contents of a granular to crystalline structure.