Stem Cells of Olfactory Cells During Development

Abstract

There are two types of basal cell in the basal region of the olfactory epithelium of mice: (1) The basal cells proper, which are in direct contact with the basement membrane, are positive for keratin as detected with anti-keratin antibodies [1–4]. (2) The globose basal cells, which lie between basal cells proper and olfactory cell nuclei, or often close to the basement membrane, are stained positively with antineural cell adhesion molecule (N-CAM) antibody [5,6] and are devoid of keratin [2]. An earlier study using [3 H]thymidine autoradiography revealed that basal cells proper divide and give rise to new olfactory cells via globose basal cells because olfactory cells are continuously replaced by stem cells [7]. We reported in a previous study combining immunohistochemistry of keratin with the bromodeoxyuridine (BrdU) method for labeling dividing cells that globose basal cells increase their mitotic activity after axotomy but that basal cells proper do not show any change in their mitotic rate, suggesting that globose basal cells are stem cells of olfactory cells [8]. These two types of basal cell have been shown to differentiate in the basal region of the olfactory epithelium at birth [2]; however, the changes in the mitotic activity of these cells during postnatal development have not been investigated.