[Comparative anatomical study on the ductal systems of rabbit and cat parotid glands]

A comparative study on the ductal systems of rabbit and cat parotid glands was performed by scanning and transmission electron-microscopies, and by light microscopy. Stereological structures of both ductal systems, which were observed as resin casts, resembled one another closely. Each branch showed repeated tree-like ramifications and the striated duct and the intercalated duct took a short linear course. The development of these ducts was poor. Numerous micromorphological differences and resemblances between rabbit and cat were found: Acinus 1. Rabbits had serous acini; and cats, seromucous ones. 2. In both specimens, secretory material was present in the intercellular spaces and these spaces were enlarged. 3. Secretory granules surrounded by a limiting membrane were present in the terminal lumen in cats, but not in rabbits. Intercalated duct 4. Small secretory granules occupying the supranuclear portion were present in rabbits and cats except the proximal region of the striated duct in rabbits. 5. Spherical secretory granules were present in the lumen in cats, but not in rabbits. Striated duct 6. The walls of the duct in both animals were composed of three types of cells; the light cell, the dark cell, and the basal cell. 7. Small secretory granules occupied the apical portion of the light cell in cats. 8. Spherical secretory granules were observed in the lumen in cats, but not in rabbits.