Postnatal restoration of the mouse urinary bladder urothelium.
Mouse urothelium is disrupted just before birth, followed by a postnatal restoration process which includes cell proliferation, death and differentiation. We assessed urothelial proliferation by the expression of proliferating cell nuclear antigen (PCNA), desquamation by electron microscopy, and apoptosis by TUNEL staining and urothelial differentiation by the expression of uroplakins and cytokeratin 20 (CK20) as well as the apical plasma membrane maturation. Our results indicated that urothelial proliferation was high from birth until about the 14th postnatal day. A majority of basal cells and even occasional superficial cells were PCNA positive during the first 5 postnatal days. Cell death occurred during the first 9 postnatal days. Between birth and day 5, single cells underwent apoptosis, whereas between days 6 and 9 cells mainly desquamated. CK20 and uroplakins were expressed in all superficial cells in postnatal urothelium. Their subcellular distribution characteristically changed in accordance with the progressive differentiation of superficial cells. During the urothelial postnatal development, proliferation activity slowly decreases to the proliferatively quiescent urothelium of the adult animal. Apoptosis is present in the first 9 postnatal days and within a few days of this period it appears simultaneously with desquamation. Superficial urothelial cells gradually differentiate, which is reflected in the changeable morphology of the apical plasma membrane.
Erman
A
A
Institute of Cell Biology, Medical Faculty, Lipiceva 2, 1000 Ljubljana, Slovenia. aerman@ibmi.mf.uni-lj.si
Jezernik
K
K
Stiblar-Martincic
D
D
Romih
R
R
Veranic
P
P
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002455:Cell Division; D002462:Cell Membrane / Q000648:ultrastructure; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling / Q000379:methods; D007381:Intermediate Filament Proteins / Q000378:metabolism*; D053554:Keratin-20; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D018613:Microscopy, Confocal; D059470:Tetraspanins; D001743:Urinary Bladder / Q000166:cytology* / Q000378:metabolism*; D060170:Uroplakin II; D060171:Uroplakin III; D060167:Uroplakin Ia; D060169:Uroplakin Ib; D019459:Urothelium / Q000166:cytology / Q000254:growth & development* / Q000648:ultrastructure
D007381:Intermediate Filament Proteins; C507499:KRT20 protein, human; D053554:Keratin-20; C489975:Krt20 protein, mouse; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D059470:Tetraspanins; C086452:UPK1B protein, human; C554658:UPK2 protein, human; C490123:Upk1a protein, mouse; C490124:Upk1b protein, mouse; C554659:Upk2 protein, mouse; D060170:Uroplakin II; D060171:Uroplakin III; D060167:Uroplakin Ia; D060169:Uroplakin Ib