Localization and distribution of laminin in the basal lamina of certain mechanoreceptors--an immunogold study

The applied immunogold cytochemical technique in investigating the cytologic distribution of the laminin (LAM) molecule in the capsulated Pacinian and Herbst mechanoreceptors shows the presence of LAM around most elements of the receptor structures. The LAM immunoreactivity (LAM-IR) is best expressed in the vicinity of the perineural capsule cells of both receptor types, where it is primarily concentrated around the perinuclear regions as well as the cytoplasmic lamellae. Such a localization overlaps with the already known ultrastructural localization of a basal lamina (BL) around these cells. Laminin immunoreactivity is less well expressed around the modified Schwann cells. Even in these cells, however, there is an apparent immunoreaction around the cytoplasmic lamellae regardless of the lamellar location. In both receptor types, there is no LAM-IR in the cells of the subcapsular space. Of particular significance we consider the localization of gold particles (respectively the presence of a BL) between the innermost lamellae of the modified Schwann cells and the non-myelinated part of the receptor nerve fiber and their endings, as well as around the axoplasmic protrusions of the nerve endings. We discuss the role of the BL and LAM in the investigated rapidly adapting mechanoreceptors and their trophic influence upon the sensory regions. We also assume the arresting and selective effect of these membranes in building up the ion channels of the axolemma which probably has a certain importance in mechanotransduction.