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Fine Structure of the Hepatic Sacculations of Glossobalanus minutus (Enteropneusta, Hemichordata)
Author(s) -
Benito Jesús,
Fernández Isabel,
Pardos Fernando
Publication year - 1993
Publication title -
acta zoologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.414
H-Index - 37
eISSN - 1463-6395
pISSN - 0001-7272
DOI - 10.1111/j.1463-6395.1993.tb01224.x
Subject(s) - coelom , biology , epithelium , anatomy , epidermis (zoology) , ultrastructure , cell type , pathology , myoepithelial cell , sinus (botany) , microbiology and biotechnology , cell , immunohistochemistry , immunology , zoology , medicine , genetics , genus
The hepatic region of Glossobalanus minutus is characterized by deep foldings of the dorsal side of the gut epithelium which affect the neighbouring tissues and structures: coelomic spaces, musculature and epidermis. The following cell types of the gut epithelium are described: vacuolated cells, undifferentiated cells, two types of mucous cells and two types of granular secretory cells. The nature and function of the different cell types are discussed. Data on the general ciliation and subepithelial nerve plexus of the gut epithelium are also given, with special mention of a possible neuroendocrine secretion towards the subjacent blood spaces. A well‐developed blood sinus (gut sinus) lies between the gut and the visceral peritoneum. The ultrastructural features of the gut epithelium and its close association with the blood sinus point to an absorptive function. The coelomic cavity is reduced to a narrow space limited by two peritoneal sheets (visceral and parietal) of myoepithelial nature. Amoebocyte‐like cells (coelomocytes) occur free in the coelomic fluid, and muscular, unicellular bridges are attached to both peritoneal walls across the coelomic space. The dorsal epidermis follows the gut foldings and is formed by flat, overlapping cells. The present observations are compared with previous histological, histochemical and ultrastructural data.