[Dark cells of the rat olfactory epithelium]

Two types of basal cells can be identified in the olfactory epithelium: a) the clear basal cells, round in shape, which are true stem cells capable of giving rise to the olfactory and the supporting cells; b) the dark basal cells characterized by a very irregular shape and by the presence in the cytoplasm of numerous mitochondria and bundles of microfilaments. In the aim of interpreting the significance of these dark cells we studied them with the light and electron microscope in the olfactory epithelium of male and female prepubertal and postpubertal rats. The nature of the microfilaments was investigated with the indirect immunofluorescence method for prekeratin and actin. The results show that the basal cells modify their morphology in different endocrine conditions and that microfilaments are made up by actin. Therefore, in our opinion, these cells must be considered as a particular type of supporting cells, capable of directing the cellular movement and arrangement in the olfactory epithelium, when an active cellular turnover occurs.