IMMUNOELECTRON MICROSCOPY IDENTIFICATION OF EARLY PROLIFERATING CELLSIN RAT-LIVER TISSUE DURING HYPERPLASIA INDUCED BY LEAD NITRATE

Citation
K. Rijhsinghani et al., IMMUNOELECTRON MICROSCOPY IDENTIFICATION OF EARLY PROLIFERATING CELLSIN RAT-LIVER TISSUE DURING HYPERPLASIA INDUCED BY LEAD NITRATE, Hepatology, 17(4), 1993, pp. 685-692
Citations number
50
Categorie Soggetti
Gastroenterology & Hepatology
Journal title
ISSN journal
02709139
Volume
17
Issue
4
Year of publication
1993
Pages
685 - 692
Database
ISI
SICI code
0270-9139(1993)17:4<685:IMIOEP>2.0.ZU;2-I
Abstract
Recent studies have suggested that hepatic stem cells may be involved in at least some forms of liver epithelial growth. To obtain further i nformation on this controversial hypothesis, we treated rats with lead nitrate to induce liver growth and identified the cells undergoing ea rly DNA synthesis by bromodeoxyuridine immunohistochemistry, using bot h light and electron microscopic detection methods. Eight hours after an intravenous injection of lead nitrate 100 mumol/kg, DNA synthesis w as detected in a few scattered hepatocytes and in nonparenchymal cells in portal connective tissue. At the light microscopic level, identifi cation of nonparenchymal cells was limited to bile duct epithelial cel ls. Other cell types were also labeled, but their identity could not b e established. At the ultrastructural level, however, four types of no nparenchymal cells were identified as containing bromodeoxyuridine imm unogold particles. These four types included bile duct epithelial cell s, fibroblasts, macrophages and nondescript periductular cells. These periductular cells displayed certain ultrastructural features of bile duct cells but did not line a lumen or display microvilli on their api cal membrane, nor did they reside within the bile duct basement membra ne. Because proliferation of nonparenchymal cells in portal areas prec eded that of hepatocytes, it is suggested that the former reaction ref lects a direct mitogenic effect of lead nitrate and not an adaptive gr owth response secondary to parenchymal enlargement. However, whether D NA synthesis in periductular cells or bile duct cells reflects activat ion of hepatic stem cells cannot be established from the present morph ological observations. If so, such a progenitor compartment must be do rmant because it does not seem to play a functional role in this and o ther forms of adult liver epithelial growth.