Visualization of Sensory Hair Cells in an in vivo Preparation

Abstract

In order to obtain visual control over micromechanical and electrophysiological measurements on the sensory hair cells of the fish lateral line in vivo we developed an optical method based on polarization microscopy. The thickness of the preparation prevents the use of transmitted light microscopy. The results of the investigation show that under conditions of polarized incident light illumination, visualization of the cell surface and of the hair bundles of the sensory hair cells can be realized. The image of the hair cells and bundles is formed by the light reflected back by the nerves underlying the low reflective sensory epithelium in the macula. Although at a magnification of 800 × the image of the sensory epithelium is contrast limited, under the most favourable conditions of illumination the individual stereocilia and the kinocilium of the hair bundle can be distinguished. The cupula, a jelly-like structure in which the hair bundles are embedded, does not noticeably disturb the image of the hair cells and its integrity assures physiological conditions for the apical surface of the hair cells.