The integument of glossobalanus minutus kowalevsky (Enteropneusta ptycoderidae). Ultrastructural analysis

The fine structure of the integument of Glossobalanus minutus Kowalevsky (Enteropneusta Ptycoderidae) has been examined by electron microscopy. The organization of the various cell-types of the epidermis is described. Epithelial ciliated cells extend trough the whole depth of the epithelium, reaching the basal lamina. Gland cells of four morphologically distinct types are interspersed with ciliated cells; differences in cytoplasmic structures and in secretory contents are noted. Collar cells or «choanocyte-like» cells have also been found. Cell junctions have been investigated; the only morphological specialization of the junctional surface of epithelial cells corresponds to an intermediate junction. Filament bundles of two different thicknesses, about 50 and 180 Å respectively, are often found in close association with the junctions. Possible functions of these filaments are discussed. In the deep zone of the epidermis a layer of intraepidermal neural elements is apparent. The basal lamina and connective layer are also examined. © 1978 Taylor & Francis Group, LLC.