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Comparative Morphology and Function of Hepatic Caeca in Four Enteropneusts
Author(s) -
Bridges Todd S.,
Woodwick Keith H.
Publication year - 1994
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.1463-6395.1994.tb00973.x
Subject(s) - biology , vacuole , cytoplasm , morphology (biology) , vesicle , lumen (anatomy) , ultrastructure , electron microscope , digestion (alchemy) , dorsum , anatomy , botany , zoology , microbiology and biotechnology , biochemistry , chemistry , chromatography , membrane , optics , physics
Abstract A morphological and functional study was made of the hepatic region in four enteropneust hemichordates: Schizocardium sp., Ptychodera flava, Ptychodera bahamensis , and an undescribed ptychoderid from Maui, Hawaii, using light and electron microscopy. The hepatic region of these enteropneusts, as well as others, is characterized by a brown‐green color and the presence of numerous caeca which represent dorsal extensions of the gut. These caeca extend above the dorsal surface of the worm and are organized into bilateral rows. Species‐specific differences were noted in the organizational pattern of the sacculations within rows and the morphology and histology of individual sacculations. Numerous brown‐green vesicles were discovered in both the epithelial cells and lumen of sacculations. Transmission electron microscopy revealed these bodies to be heterophagic vacuoles and residual bodies. Morphological evidence suggests that hepatic caeca are involved in intracellular digestion. Once endocytosed food particles are packaged as heterophagic vacuoles, and digestion has been completed, the residual bodies are packaged together and exuded from the cell in a spherule of cytoplasm.