HISTOLOGY, HISTOCHEMISTRY, AND ULTRASTRUCTURE OF THE HARDERIAN-GLAND OF THE SNAKE COLUBER-VIRIDIFLAVUS

Analyses of the histology, histochemistry, and ultrastructure of the Harderian gland of Coluber viridiflavus prove the gland to be compound acinar and to produce a seromucous secretion. Acinar cells (type I) contain secretory granules that are composite, consisting ultrastructurally of three distinct parts that are sharply separated. They are similar to the "special secretory granules" described in the cells of the Harderian gland of the lizard Podarcis s. sicula. Some acini of the most anterior and posterior parts of the gland are mucous. Acinar cells (type II) of this type contain secretory granules that are Alcian blue/PAS positive. At the ultrastructural level, they appear homogeneous and of low density, characteristic of mucous secretions. These mucus-secreting anterior and posterior parts of the Harderian gland may be considered as regions of initial differentiation of the anterior and posterior lacrimal glands.