The characterisation and distribution of cells lining the axillary gland of the adult green turtle (Chelonia mydas L.)

Abstract

The axillary gland of the marine turtle lies in the angle formed by the carapace and plastron. The gland is compound tubular and the secretions released by the various acini are conveyed to the exterior via a large excretory duct lined by stratified squamous non-keratinised epithelium. The main secretory areas are lined by holocrine cells, i.e. they degenerate on discharging their contents. The epithelium lining the short ducts which carry the holocrine secretions to the large excretory duct is invaginated regularly giving rise to shallow intraepithelial acini. The cells lining these acini are of two types, granular and mitochondrial. These cells communicate via complex infoldings of their lateral cell walls. The granular cells produce an acidic mucosubstance. The holocrine regions are embedded in a large amount of striated muscle and are separated from the latter by a band of collagen containing variable numbers of melanocytes. The short secretory ducts and large excretory duct have less muscle associated with them but there is a corresponding increase in the volume of collagen. When handled, the adult turtle ejects a milky fluid via the plastral pore. This pungent secretion is weakly acidic.