ELECTRON MICROSCOPY OF THE STRATIFIED EPITHELIUM LINING THE EXCRETORY CANAL OF THE DOGFISH RECTAL GLAND.

Abstract

AbstractIn spite of a renewed interest in the rectal (salt‐secreting) gland of the spiny dogfish, Squalus acanthias, the morphology of the stratified epithelium lining the central lumen and large ducts of this gland has been mentioned only briefly. The fluid removed from the duct of the rectal gland has been shown by Burger and Hess ('60a, b) and Burger ('62) to be a concentrated sodium chloride solution. The function of the stratified epithelium in the elaboration of this fluid is unknown. It is of interest to know if the stratified epithelium has morphological specializations which might suggest its function.The stratified epithelium of the central canal consists of surface cells, intermediate cells, and basal cells. Four types of surface cells can be distinguished: granular cells, mucous cells, flask‐shaped cells, and cells with large mitochondria. The intermediate cells form a loose network. In the large extracellular spaces between the intermediate cells, free cells presumably of blood origin, can be seen. The basal cells lie on a basement membrane. There is a structural resemblance of the epithelium to that of the toad bladder.