IN YOUNG PRIMARY CULTURES OF RABBIT KIDNEY CORTICAL COLLECTING DUCTS INTERCALATED CELLS ORIGINATE FROM PRINCIPAL OR UNDIFFERENTIATED CELLS

The evolution of a primary culture of rabbit kidney cortical collectin g tubule was followed over a period of 10 to 11 days. The cell types o f this segment were characterized by using monoclonal antibodies, spec ifically directed against principal (Mab 703) and intercalated (Mab 50 3) cells of the apical membrane. The activity of a H(+)pump ATPase was revealed in Mab 503-labeled cells, confirming that these cultured cel ls present characteristics of intercalated cells. The primary culture was also stained with peanut agglutinin (PNA), a specific ligand of be ta intercalated cells. During the first two days, some cells, mainly M ab 503-labeled cells, disappeared, and cell division did not occur. At 2 days, the culture showed 80% and 18% of Mab 703-labeled and Mab 503 -labeled cells, respectively. The first mitoses were observed at 2 day s. From two to four days, cell division was nestly in Mab 703-labeled cells and only rarely seen in Mab 503-labeled cells, although during t his period the proportion of Mab 703-labeled cells decreased to 44% of cells and that of Mab 503-labeled cells increased to 30%. The labelin g with PNA was curious. Up to 2 days, PNA stained Mab 503-labeled cell s, but from 4 days it stained other cells, probably dedifferentiated o nes. In our culture conditions types of cells other than Mab 703-label ed and Mab 503-labeled cells occurred. First, throughout the life of t he culture, some cells were not recognized by any monoclonal antibody; their number varied between 10 and 28% of the total cell number. Seco nd, at 10 to 11 days, some cells were labeled with both Mab 703 and Ma b 503, and the percentage of PNA-labeled cells was 72%, implying that some cells must have been recognized by both Mab 703 and PNA. It is no t yet known what these cellular types represent. Unlabeled cells were considered to be undifferentiated cells. From two to four days, the in crease in the percentage of Mab 503-labeled cells in spite of their lo w mitotic activity would indicate that in a young primary culture of c ortical collecting tubules, some Mab 503-labeled cells probably origin ate from Mab 703-labeled or from undifferentiated cells.