Ultrastructural morphology of enzyme-dissociated cochlear sensory cells

Enzyme-dissociated chinchilla cochlear sensory cells maintained excellent cellular integrity for two hours or more when kept in the tissue culture medium. The healthy appearing sensory cells maintained their refractile characteristics. Early signs of cell stress were shown by the aggregation of nuclear chromatin, clustering of cytoplasmic contents in the central portion of the supranuclear region of the outer hair cells, and Brownian motion of the mitochondria. The ultrastructural morphology of the enzyme-dissociated outer hair cells was generally well maintained, but with such subtle changes as increased vesicle formation, condensation of mitochondrial matrix, nuclear chromatin aggregation, and vacuole formation. Some of the vesicles present in the infranuclear region are interpreted to be neural synaptic vesicles that have accumulated in the cell, or they may be dilated microsomes or vesicles formed from the degenerating cytoplasmic membrane system (ER system) as a sign of cell stress or degeneration.