Mouse urothelial cells in early postnatal development--proliferation and apical plasma membrane specialization

The purpose of this work was to investigate proliferation and differentiation of the mouse urothelial cells from the day of birth until the 5th postnatal day. The expression of proliferating cell nuclear antigen (PCNA) was studied immunocytochemically and the differentiation of apical plasma membrane of superficial cells was analysed by scanning microscopy. It was established that proliferation activity is very high during all five days since PCNA positive cells are seen in the superficial and in basal cell layer of the urothelium. Results of scanning microscopy show that the differentiation of superficial urothelial cells is a nonsynchronous process, which gradually progresses from the day of birth and leads into homogeneous population of terminally differentiated superficial cells on the 5th postnatal day.