Untreated organ cultures of normal @entity35 bladder can be maintained for long periods, up to 160 days, in a supplemented Waymouth's medium MB 752/1. During that time, the urothelium retains a similar appearance to that seen in vivo, namely a three-cell thick epithelium with specialised superficial cells whose characteristic surface features are identifiable by scanning electron microscopy. These superficial cells cover the major part of the explants, but the surface features of basal and intermediate cells can be observed on the cut edges and re-epithelialising surfaces of the explant. These are described and illustrated. When normal cultures are treated with the direct-acting carcinogen, @entity7044 ( @entity7045 ), the in vitro response of the urothelium resembles to a certain extent the in vivo response to @entity7045 instilled directly into the bladder. A histological progression is seen through mild to severe @entity1141 which resembles @entity2735 . However, no marked changes in growth pattern, such as the development of @entity4383 are seen. It is suggested that this is related to the failure of the vascular and stromal elements of the explants to respond to @entity7045 treatment in vitro. The development of @entity1141 is reflected by marked changes in cell surface differentiation, including development of @entity1893 , which closely resemble those seen following @entity7045 treatment in vivo. These changes appeared earlier and were far more severe in vitro than in vivo. The significance of @entity1893 in bladder cultures is considered. A few were seen in control cultures but primarily on epithelial outgrowths onto the Millipore filter support, suggesting a relationship to the distance of the urothelium from viable stromal support. In the @entity7045 -treated cultures, they were numerous and found on the surface of cells covering most of the explants. They were not solely related to the proliferative state of the urothelium in these cultures. This in vitro culture system provides a useful model with which to study the effects on the urothelium of various known and suspect carcinogens.

@entity7044 induces @entity1141 and cell surface markers of neoplasia in long-term XXXX bladder organ cultures.

@entity7045 :: ('CHEBI:50102', 'Chemical') :: ['MNU'] @entity1893 :: ('MESH:D008228', 'Disease') :: ['pleomorphic microvilli'] @entity2735 :: ('MESH:D002278', 'Disease') :: ['carcinoma in situ'] @entity4383 :: ('MESH:D020518', 'Disease') :: ['papillary or nodular hyperplasia'] @entity7044 :: ('MESH:D008770', 'Chemical') :: ['N-methyl-N-nitrosourea'] @entity35 :: ('10116', 'Species') :: ['rat'] @entity1141 :: ('MESH:C535662', 'Disease') :: ['dysplasia', 'urothelial dysplasia']
@entity35 :: (10116,Species) :: ['rat']
