Development of the fetal rat liver: ultrastructural and stereological study of hepatocytes

Transcriptional regulation of liver development

“…Between Days 12 and 17 dpc the pre-hepatocytes gradually adopt a more cuboidal morphology (Medlock and Haar, 1983;Vassy et al, 1988). During late stages of gestation the pre-hepatocytes begin to establish the polarized epithelium that is an essential feature of the hepatic parenchyma (Medlock and Haar, 1983;Vassy et al, 1988). It is during these later stages that the bile canalicular network is established and the expression of tight junction, intermediate junction and cell adhesion proteins is detected (Stamatoglou et al, 1992;Stamatoglou and Hughes, 1994).…”

“…Throughout earlygestational stages of liver development the pre-hepatocytes maintain a stellate appearance, contain a large irregular nucleus and posses relatively few distinct organelles. Between Days 12 and 17 dpc the pre-hepatocytes gradually adopt a more cuboidal morphology (Medlock and Haar, 1983;Vassy et al, 1988). During late stages of gestation the pre-hepatocytes begin to establish the polarized epithelium that is an essential feature of the hepatic parenchyma (Medlock and Haar, 1983;Vassy et al, 1988).…”

“…Indeed between 13 and 20 dpc in the rat pre-hepatocytes on average undergo 8 doublings and the liver expands in volume by 84-fold (Greengard et al, 1972;Vassy et al, 1988;Grisham and Thorgeirsson, 1996). Gene-inactivation studies in mice have outlined a pathway that links the growth promoting properties of septum transversum mesenchyme to regulation of the hepatocyte cell cycle, recently reviewed by Zaret (1998).…”

Embryonic development of the liver†

“…Studies in rat embryos have shown that between E13.5 and E20.5, the volume of the liver expands 84-fold, during which time the hepatoblasts undergo 8-doublings. [85][86][87] Several mechanisms have been identified through gene knockout studies in mouse embryos that are required for growth of the liver. These include protection of the fetal liver from tumor necrosis factor ␣-mediated apoptotic cell death through the nuclear factor B signaling pathway, regulation of cell proliferation by the transcription factors Xbp1 and Foxm1b, and signaling mechanisms that are mediated through the AP-1 transcription factor cJun.…”

Study of hepatocyte differentiation using embryonic stem cells

“…The onset of synthesis of secreted proteins is around rat embryonic day 12, while deposition of glycogen rosettes is identifiable after embryonic day 18 in the rat [Duncan, 2003]. It was also shown that the fetal rat liver tissue gets the polygonal characteristic adult structure just prior to birth [Vassy et al, 1988]. This data suggests that hepatocytes in different developmental phases are functionally diverse and we may discriminate between them.…”