reticularislamina

Reticular lamina, or lamina reticularis, is a thin, lattice-like extracellular layer that forms the apical boundary of the sensory epithelium in the organ of Corti within the cochlea. It is composed primarily of the apical surfaces and junctional complexes of the hair cells (inner and outer) and of supporting cells such as pillar cells and Deiters’ cells, whose processes interdigitate to create a continuous sheet across the organ. The reticular lamina lies just beneath the tectorial membrane and above the cuticular plates of the hair cells.

Functionally, the reticular lamina acts as the roof of the organ of Corti, separating the endolymph in the scala media from perilymph in the scala vestibuli and scala tympani. By forming a barrier at the apex of hair cells, it helps maintain the unique ionic composition of endolymph and provides mechanical integrity for the stereocilia as they deflect in response to sound. The structure is reinforced by tight junctions between adjacent cells, contributing to ion homeostasis and the proper functioning of mechanotransduction.

Development and clinical relevance are tied to its role as a boundary within the cochlea. The reticular lamina develops during cochlear maturation from the apical membranes of hair cells and surrounding supporting cells. Disruption of this lamina, due to trauma, ototoxic injury, or disease, can compromise barrier function, alter ionic balance, and contribute to sensorineural hearing loss.