Cell population kinetics in the epithelium of the colon of the male rat.

The present study was undertaken in order to try to define some of the kinetic parameters in the colonic mucosa of normal Wistar rats. Preliminary observations showed considerable morphological differences in the mucosa from site to site along the length of the colon. In particular the height of the crypts (measured in cells) was variable. In addition labelling index studies demonstrated dramatic variations in the distribution of labelling along the length of the crypts from site to site in the bowel. A single site in the descending colon was selected for more detailed study using a stathmokinetic agent, vincristine, and the continous labelling technique with tritiated thymidine. The results of these investigations suggest that there exists at the base of the crypt a subpopulation of cells cycling more slowly than the cells in the rest of the proliferative compartment. Growth fraction appears to fall with rising cell positions within the crypt.     

Cell population kinetics of the mouse lens epithelium

The dividing lens epithelium of 8-week-old CF1 mice consists of a monocellular layer of about 31,000 cells and does not include the postmitotic cells of the meridional rows and another postmitotic zone of seven cell positions' width immediately anterior to the rows. The latter two populations contain approximately 3,600 and 9,000 cells, respectively, for a total of 44,000 cells in the entire lens epithelium. Autoradiographic analysis based upon mitotic index and cell cycle times indicates that the epithelium produces 207 new lens fibers a day. Throughout the 20-day period of study, labeled cells appeared almost entirely as pairs following a single dose of ³H-thymidine and clusters of labeled nuclei were not seen. Moreover, the number of labeled cells dropped only slowly with time, as did the grain counts. These observations indicate that logarithmic division “cascade” does not occur in the lens. The dividing cell population consists largely of a slowly cycling stem cell group, dividing once about every 17–20 days, and consisting of some 5,000 cells. A subpopulation may exist which undergoes two rapid consecutive divisions before becoming postmitotic, but this is too small to make a significant contribution to lens fiber production. Four days are required to transit the postmitotic zone, and an additional 43 or so are needed to transit the meridional rows and differentiate into anucleate lens fibers. Data from other laboratories indicate that the entire process, from mitosis to final differentiation, requires about 4 months. Hence, most of this time is spent in migration of nondividing cells.     

Cell kinetics of mouse urinary bladder epithelium

A dose of 0.2 ml propylene glycol (1,2 propanediol) was injected subcutaneously into 12 hairless mice three times a week for three months. Four animals were killed at 1, 2 and 3 months and micro-flow fluorometric histograms of the bladder epithelial cells were made. The proportion of cells in diploid S phase was not much altered, but the proportion of tetraploid S-phase cells was significantly reduced and at three months DNA synthesis in tetraploid cells completely disappeared. The proportion of diploid cells increased, the proportion of tetraploids was slightly reduced and almost all octoploid cells disappeared. The changes are qualitatively similar to those seen after the bladder carcinogen dibutylnitrosamine, and after repeated injections of cyclophosphamide, but quantitatively much less pronounced. They can be explained as a result of cell toxicity whereby propylene glycol kills some bladder epithelial cells and disturbs the mechanism of repeated DNA synthesis. Propylene glycol is thus not a completely harmless solvent and when the kinetic effects of bladder carcinogens dissolved in propylene glycol are studied, the effect of the solvent alone must be accounted for.     

Cell kinetics of vocal fold epithelium in rats.

In order to investigate the kinetics of vocal fold epithelium a bromodeoxyuridine-anti bromodeoxyuridine method has been applied in vivo at both light and electron microscopy level. This method is able to define the length of both epithelium turnover and cell-cycle in basal elements, as well as the existence of a higher proliferation rate during night time in comparison with day time. Moreover distinct labeling patterns observed in incorporating cells allow us to define the precise localization in S-phase of cycling elements.     

The brush cells of the common bile duct of the rat

Summary Two different fixative procedures (immersion and perfusion) and four different fixative solutions were used in order to obtain the best preservation of the brush cells of the common bile duct of the rat. The results indicate that only perfusion fixation through the common bile duct is suitable, independent of the fixative solutions and their osmolarity.Numerous brush cells were seen in the proximal and distal regions of the common bile duct. In these locations, they could be implicated in a registration and/or regulation of intraluminal pressure variations.     

Monoclonal antibodies directed against rat liver epithelial cell lines selectively recognize bile duct epithelium in livers of adult rats

Monoclonal antibodies directed against antigens on rat liver epithelial cell lines were prepared. Three antibodies, 4C3, 19C6, and 3C2, recognized surface antigens present (although in different quantities) on eight epithelial cell lines tested, irrespective of whether they were normal or transformed. For MAb 3C2, the primary antigen common to all but one cell line showed a Mr of 135 kD. In paraffin sections of liver tissue, two antibodies, 40 and 19C6, reacted exclusively with bile duct epithelium, whereas the MAb 3C2 additionally reacted with sinusoidal endothelium and the endothelium of the portal venules. In sections of livers from rats exposed to diethylnitrosamine, the MAb 19C6 selectively stained bile duct-like structures in cholangiomas, while other preneoplastic and neoplastic lesions were not stained. These results demonstrate that the monoclonal antibodies obtained may prove useful for investigating cell lineages related to propagable liver epithelial cell lines and suggest that these cells may be derived from terminal bile ductular cells.Abbreviations ABTS2 2,2azinobis(3-ethylbenzthiazolinesulfonic) acid - ARL adult rat liver - DEN diethylnitrosamine - FCS fetal calf serum - MAb monoclonal antibody - PAP peroxidase antiperoxidase