Distribution of components of basal lamina and dystrophin-dystroglycan complex in the rat pineal gland: differences from the brain tissue and between the subdivisions of the gland.

The pineal gland is an evagination of the brain tissue, a circumventricular neuroendocrine organ. Our immunohistochemical study investigates basal lamina components (laminin, agrin, perlecan, fibronectin), their receptor, the dystrophin-dystroglycan complex (beta-dystroglycan, dystrophin utrophin), aquaporins (-4,-9) and cellular markers (S100, neurofilament, GFAP, glutamine synthetase) in the adult rat corpus pineale. The aim was to compare the immunohistochemical features of the cerebral and pineal vessels and their environment, and to compare their features in the distal and proximal subdivisions of the so-called 'superficial pineal gland'. In contrast to the cerebral vessels, pineal vessels proved to be immunonegative to alpha1-dystrobrevin, but immunoreactive to laminin. An inner, dense, and an outer, loose layer of laminin as two basal laminae were present. The gap between them contained agrin and perlecan. Basal lamina components enmeshed the pinealocytes, too. Components of dystrophin-dystroglycan complex were also distributed along the vessels. Dystrophin, utrophin and agrin gave a 'patchy' distribution rather than a continuous one. The vessels were interconnected by wing-like structures, composed of basal lamina-components: a delicate network forming nests for cells. Cells immunostained with glutamine synthetase, S100-protein or neurofilament protein contacted the vessels, as well as GFAP- or aquaporin-immunostained astrocytes. Within the body a smaller, proximal, GFAP-and aquaporin-containing subdivision, and a larger, distal, GFAP-and aquaporin-free subdivision could be distinguished. The vascular localization of agrin and utrophin, as well as dystrophin, delineated vessels unequally, preferring the proximal or distal end of the body, respectively.