Ultrastructural localisation of alpha-fetoprotin (AFP) in regenerating mouse liver poisoned with CCL4

Abstract

The AFP-synthesizing cells were identified by ultrastructural localization of the antigen in regenerating liver of adult mice after CCl4 poisoning. An indirect immunoperoxidase method with rabbit anti-mouse AFP and peroxidase conjugates of anti-rabbit IgG or their Fab' was used. Good preservation of AFP and tissue structure, and sufficient permeability for the conjugates were obtained after 20' prefixation of small liver specimens in 8% formaldehyde -0.05% glutaraldehyde followed by 16 h fixation in 8% formaldehyde. The intracellular localization of AFP observed in the light microscope in most cases corresponded to its synthesis and secretion. It was found in two cell types, both concentrated mainly in the perinecrotic zones and constituting only a small part of the whole cell population. Most of the AFP-producing cells were normal differentiated hepatocytes without any structural signs of damage. A few smaller cells with active AFP synthesis were present in some animals. By their ultrastructure they resembled the oval cells found during chemical hepatocarcinogenesis in rats.

Hepatic Fibrosis Is Enhanced and Accompanied by Robust Oval Cell Activation after Chronic Carbon Tetrachloride Administration to Egr-1-Deficient Mice

“…27 To study the oval cell response in mice and rats, investigators combine two different agents: a hepatotoxin or 2/3 partial hepatectomy to induce liver injury and an antimitotic or DNA-damaging agent to inhibit hepatocyte proliferation. 41,46 -50 Aside from a single report that suggested an inconsistent and rare presence of cells with oval cell-like morphology in liver parenchyma after CCl 4 exposure, 51 the current study is the first to fully characterize a robust activation of the oval cell response in mice using CCl 4 in the absence of exogenous inhibitors of hepatocyte proliferation.…”

Expression of nestin–green fluorescent protein transgene marks oval cells in the adult liver

“…In this model, fast liver regeneration after a single CCl 4 administration is due to the high proliferative activity of hepatocytes. Although the involvement of oval cells in this process of regeneration is considered to be quite marginal (see Sell, 2001Sell, , 2003, a measurable proliferative activity of oval cells has been reported in this CCl 4 mouse liver regeneration model (Engelhardt et al, 1984; this model stands in contrast to the partial hepatectomy model, for which no contribution of oval cells has been reported). Moreover, several rounds of CCl 4 administration induce the appearance of small aggregates of proliferating oval cells (Faktor et al, 1982; note that prolonged, every 3-4 days for several months, administration of CCl 4 can induce hepatic tumors).…”

“…Thus, nestin-GFP-expressing Bgp1-positive cells may represent a transitional cell type between oval cells and hepatocytes. Such transitory cells derived from oval cells have been found to express some other hepatocyte markers, for example alpha-fetoprotein (AFP; Tchipysheva et al, 1977;Engelhardt et al, 1984), a serum glycoprotein produced by hepatocytes in the embryonic and regenerating liver as well as by hepatocellular tumors (see Abelev, 1971). We could not detect AFP in GFP-expressing cells in the regenerating liver after single or multiple rounds of administration of CCl 4 ( Fig.…”

Heterogeneity and plasticity of hepatocyte lineage cells

“…51 This produces sharply delineated centrolobular necrosis at 36 to 48 hours after administration, followed at 48 hours by proliferation of adjacent hepatocytes, which restores the necrotic area within 1 to 2 weeks. [52][53][54] In this case, transient elevation of ␣-fetoprotein (AFP) in the blood may be the result of production by proliferating hepatocytes adjacent to the necrotic zone, 55 which switch from albumin to AFP production. 56 There is little, if any, evidence of proliferation of ductal or periportal oval cells.…”