Ultrastructure of the reticulate uterus and specific features of matrotrophy in three species of higher cestodes (Cestoda, Cyclophyllidea)

Abstract

The ultrastructure of the reticular uterus has been analyzed in pregravid and gravid proglottids of cyclophillid cestodes dwelling in water (Alcataenia dominicana and A. larina) and in terrestrial hosts (Arostrilepis tenuicirrosa). Cells of the medullary parenchyma surrounding the uterus are filled with lipid inclusions in all species investigated. The hypertrophic development of small excretory ducts that surround the uterus, contact the uterine epithelium, and penetrate the diverticula is characteristic of Alcataenia dominicana and Arostrilepis tenuicirrosa. A comparative analysis of the results and the data available for other cestode species allow for the assumption that the reticulate structure of the uterus, lipid accumulation, and contacts between the uterine epithelium and the excretory ducts are morphological and functional adaptations that enable matrotrophy and the attainment of maximal fecundity by cyclophillid cestodes.