Notenboom R G, Moorman A F, Lamers W H
Department of Anatomy and Embryology, University of Amsterdam, Academic Medical Centre, The Netherlands.
Microsc Res Tech. 1997 Dec 1;39(5):413-23. doi: 10.1002/(SICI)1097-0029(19971201)39:5<413::AID-JEMT4>3.0.CO;2-H.
To resolve an apparent discrepancy in the developmental appearance of glutamine synthetase (GS) protein in rat [Gaasbeek Janzen et al. (1987) J. Histochem, Cytochem., 35:49-54] and mouse [Bennett et al. (1987) J. Cell Biol., 105:1073-1085] liver, we have investigated its expression during liver development in the mouse and compared it with that of carbamoylphosphate synthetase I (CPS). The expression of glutamate dehydrogenase was used as a marker to identify all hepatocytes in these strongly hematopoietic livers. GS protein accumulation starts in mouse hepatocytes at embryonic day (ED) 15. The first hepatocytes in which the enzyme accumulates were found around the major hepatic veins. CPS protein was found to accumulate in mouse hepatocytes from ED 13 onward: first, at the center of the median and lateral lobes, but temporarily not at the periphery of these lobes and not at the caudate lobe. The initial phase of accumulation of GS and CPS protein was characterized by a heterogeneity in enzyme content between hepatocytes. By ED 17, both enzymes were detectable in all hepatocytes at the center of the median and lateral lobes. This event marked the onset of the development of the complementary distribution of the enzymes typical of zonal heterogeneity in the adult mammalian liver. However, during the perinatal period, the pericentral hepatocytes temporarily accumulated CPS protein. We also observed heterochrony between species in the appearance of CPS protein in the small intestine.
为了解决大鼠[Gaasbeek Janzen等人（1987年）《组织化学与细胞化学杂志》，35:49 - 54]和小鼠[Bennett等人（1987年）《细胞生物学杂志》，105:1073 - 1085]肝脏中谷氨酰胺合成酶（GS）蛋白发育外观上的明显差异，我们研究了其在小鼠肝脏发育过程中的表达，并将其与氨甲酰磷酸合成酶I（CPS）的表达进行了比较。谷氨酸脱氢酶的表达被用作标记来识别这些造血功能很强的肝脏中的所有肝细胞。GS蛋白在胚胎第15天开始在小鼠肝细胞中积累。发现该酶最早积累的肝细胞位于主要肝静脉周围。发现CPS蛋白从胚胎第13天起在小鼠肝细胞中积累：首先在中叶和外侧叶的中心，但这些叶的周边以及尾状叶暂时没有积累。GS和CPS蛋白积累的初始阶段的特征是肝细胞之间酶含量的异质性。到胚胎第17天，在中叶和外侧叶中心的所有肝细胞中都可检测到这两种酶。这一事件标志着成年哺乳动物肝脏典型的区域异质性中酶互补分布发育的开始。然而，在围产期，中央周围的肝细胞暂时积累了CPS蛋白。我们还观察到小肠中CPS蛋白出现的种间异时性。
