A. Flock et al., VITAL STAINING OF THE HEARING ORGAN - VISUALIZATION OF CELLULAR STRUCTURE WITH CONFOCAL MICROSCOPY, Neuroscience, 83(1), 1998, pp. 215-228
Cells inside the intact organ of Corti were labelled with fluorescent
probes reflecting various aspects of structure and function. The dyes
were introduced into the perilymphatic space by perfusion of the scala
tympani of the temporal bone from the guinea-pig maintained in isolat
ion. The dyes were able to diffuse through the basilar membrane and in
to the organ of Corti where they were spontaneously absorbed by the se
nsory and supporting cells. Confocal microscopic observation was made
through an opening in the apex of the cochlea. A number of different d
yes were used; a carbocyanine dye which stains mitochondria; two styry
l dyes which are absorbed by the cell membranes and calcein, a cytopla
smic marker that fluoresces in vital cells. Extracellular space was st
ained by a cell-impermeant Dextran-fluorescein. The most striking find
ing was that the membrane dyes preferentially stained the sensory cell
s and neural elements whereas the staining of the supporting cells was
faint. The cytoplasmic dye in general stained sensory and supporting
cells to the same extent. By tilting the organ, a view could be obtain
ed from the side like a radial section through the organ. Outer and in
ner hair cells with their sensory hairs, nerve fibres and nerve ending
s, especially under the inner hair cells, could be seen in profile. In
troduction of a high molecular weight Dextran into the endolymphatic s
pace outlined the tectorial membrane which was seen in negative contra
st. The simultaneous perfusion with a membrane dye stained the hair ce
lls and their sensory hairs. Merging of the two images gave the possib
ility to examine, in the living tissue, the cilia to tectorial membran
e relationship. Of general interest is the finding that the membrane d
yes preferentially stained the sensory and neural elements of the nerv
ous system, represented here by the hair cells and nerve fibres of the
inner ear. (C) 1997 IBRO. Published by Elsevier Science Ltd.