Abstract
Development of the vomeronasal organ in the golden hamster was chronologically examined by light and electron microscopy. This organ was embryologically derived from the olfactory placode and appeared as a tubular structure of the neuroepithelium on the medial wall of the nasal pit on either side at 11 days of gestation. At 12 days of gestation, this organ was completely separated from the nasal cavity and encircled by the immature vomeronasal cartilage. At 13 days of gestation, within the organ, the respiratory epithelium became easily distinguishable from the sensory epithelium. At 14 days of gestation the venous sinus and Jacobson's glands appeared, and this organ was equipped with all the histological components until birth. This organ began to communicate with the nasal cavity at 2 days after birth. The sensoly epithelium of this organ consisted of undifferentiated cells in the early fetal life. These stem cells were gradually differentiated into sensory and supporting cells. These cells were rather slowly maturated in their fine structure. For example, only some sensory cells became first provided with microvilli on their free surface at 8 days after birth. Even at 10 days after birth, some sensory cells were still devoid of microvilli and undifferentiated cells were sometimes observed in the sensory epithelium as well. Therefore, the olfactory function in the early postnatal life seems to be solely ascribed to the olfactory epithelium under these morphodifferentiation though the vomeronasal organ might be related with some kind of olfaction after this period.
