An autoradiographic assessment of epithelial cell proliferation and post-natal maturation of the tracheal epithelium in infant ferrets

The tracheal epithelium of infant ferrets undergoes rapid postnatal maturat ion over the first month of life to achieve the pseudostratified columnar c onfiguration characteristic of the large airways of other mammals. We have used in vivo pulsing with tritiated thymidine ((HT)-H-3) to elicit autoradi ographic labeling of cells synthesizing nucleic acids in order to character ize more fully the contribution to development of different cell types comp rising the nascent epithelial layer during this period of rapid growth. The se studies indicate that two distinct populations of epithelial cells posse ss proliferative potential and contribute to the establishment of the matur e adult epithelial layer: These investigations further confirm the mitotic potential of basal cells during a period of rapid postnatal growth sold dev elopment of the tracheal epithelial layer. These studies also document the contribution to early airway development by non ciliated cells, which predo minate on the luminal border of the ferret trachea at birth. The temporal a nd histologic patterns of airway epithelial maturation during post-natal li fe in the ferret as contained in this study exhibit similarities to those w hich occur with recovery from injury by infection and irritant exposure in mature airways. Thus, the characterization of epithelial cell compartments having proliferative potential may provide insights into the mechanisms whe reby normal airway epithelial organization is established and maintained du ring development as well as the possible recapitulation of these mechanisms during times of epithelial regeneration following injury. Anat Rec 256:242 -251, 1999. (C) 1999 Wiley-Liss, Inc.