Introduction and purpose: The vomeronasal organ (VNO), through detecting pheromones, has an important role in many social and sexual behaviors in mammals. It also mediates defensive behaviours through detection of protein pheromone homologs. This work provides detailed morphological description of the developing "non sensory" epithelium (NSE) of the rabbit VNO.
Tools and method: Histological, immunohistochemical and morphometric techniques were used to study the NSE of the VNO in developing female rabbit. The following postnatal ages (five animals each) were used: new born, one week, two weeks and one month.
Result and interpretations: The rabbit NSE of VNO consisted of pseudostratified columnar partially ciliated epithelium. In addition to basal cells, it contained ciliated and three types of non ciliated columnar cells; dark, light and pale. Mitotic and apoptotic figures were observed during the first week. At birth, the dark cells which were the commonest type showed primary cilia extending from their surfaces. The light cells possessed large nucleus and numerous lysosomes. The pale cells had electron lucent cytoplasm. Their apexes projected above the surface and had constrictions like the olfactory knobs. They were found extending processes around the cells invading the epithelium which included neutrophils, lymphocytes and macrophages. Presence of subsurface mitochondria and clear vesicles in their cytoplasm suggested their involvement in ionic transport. Nucleolus-like bodies were observed in the cytoplasm of dark and basal cells up to two weeks postnatal. Scanning electron microscope revealed ciliated cells to be arranged singly, in clumps or in dense populations of cells. The structural features of growth of the rabbit VNO-NSE reflected a peculiar structure which consequently would reflect a peculiar function.