Age-related changes in the neurosensory epithelium of the mouse vomeronasal organ: Extended period of post-natal growth in size and evidence for rapid cell turnover in the adult

The total number of neurosensory cell in the mouse vomeronasal organ was estimated during postnatal development by counting the cell density and measuring the total volume of the neurosensory cell layer. There is a 43% increase in neurosensory cell number between 1 and 4 months of age, followed by a 21% fall in cell number between 4 and 8 months. There is no further significance change in cell number between 8 and 18 months of age. Cell division was shown to be occuring in the vomeronasal organ of animals at 7 months of age by labelling dividing cells with [³H]thymidine continuously administered by means of implated ‘osmotic pumps’. At least 1 in 6 cells were labelled by 12 days of thymidine administration, indicating a turnover time of 2–3 months for the whole epithelium. This raises the general problem of how a fixed central nervous system accomodates a changing peripheral input.