Identification of the holocrine oil gland in gills of silver carp using semi-thin sections and transmission electron...

Gills are associated with a gland known as the cervical gill slit gland. Little is known regarding the composition, function, and nature of the secretion from the gill slit glands. The current work used semi-thin sections and transmission electron microscopy to analyze the morphological aspects of the gill or brachial gland in the apparently, three healthy silver carp (H. molitrix). The oil cells' basal zone had a flattened profile, a prominent nucleus with euchromatin and distinct nucleuses, and cytoplasm with relatively few lipid droplets and an indistinguishable smooth endoplasmic reticulum. The maturation zone takes on a polyhedral form, has pronounced SER, and accumulates various lipid droplets. They have a dilated smooth nuclear membrane and a dilated SER. Lipid droplets may be associated with the SER. The pyknotic nucleus identified damaged oil cells that had empty spaces and were involved in different stages of making lipids connected to the formation of small sacs. More studies should be done to explore the chemical properties of the secretion, and the tissue features of the secretory epithelium to gain a clearer understanding of the signal produced by the gill slit gland.