[The caudal gland in the cat is a hepatoid gland]

The cat supracaudal gland is usually considered as a conglomeration of massive sebaceous glands, although the author of the only detailed description of its structure stated that it is a hepatoid gland (HG) of lower order. Investigation of the supracaudal gland in adult cats of both sexes showed that it is a massive layer of HGs opening either into dilated follicles of coarse hairs or into large cisterns. These glands possess all features specific for HGs: polyhedral cells, a network of intracellular canaliculi, abundant cytoplasmic protein granules, release of protein structures from the cells to adjacent canaliculi. The reasons for misinterpreting certain structural properties are discussed. It was shown that the cat caudal gland is a typical "embryonal" HG previously described in dogs and certain hollow-horned ruminants. They secrete protein and hydrophobic lipids, have wide excretory ducts, are connected with coarse hairs, are devoid of cysts, and have no sexual dimorphism. Formation of cisterns, special secretion receptacles of the cat supracaudal gland, was monitored. It begins with stagnation of the lipid-protein secretion in the hair follicle and progresses until transformation of the whole glandular lobe to the cistern and dissolving of the hair shaft in it.