Characterization of trabecular cells in the gonad of Haliotis asinina Linnaeus

摘要

Trabeculae are the connective tissue sheets that extend perpendicularly from the outer capsules of both the testis and ovary to make contact at their innermost ends with the inner capsules separating the gonad from the hepatopancreas. Thus they divide the gonad into small compartments, and each trabecula forms the axis for individual spermatogenic or oogenic units, from which maturing germ cells are generated. When studied by light and electron microscopes, each trabecula is composed of central capillaries surrounded by muscle cells, collagen fibers, fibroblasts, and granulated cells that contain large rugby-shaped electron dense granules about 270 X 550 nm in size. The granulated cells branch extensively, and their processes become closely associated with bundles of nerve fibers that contain two types of granules, i.e., electron-dense and electron-lucent spherical-shaped granules with a diameter of about 165 nm and 150 nm, respectively. Thus, bundles of nerves and branches of granulated cells provide profuse innervation of the capsules and trabeculae. The granulated cells may be endocrine cells of the gonad which produce certain gonadotrophic factors yet to be identified.