Cytological Studies on the Liver Tissue in the Latter Half of Embryonic Stage

Abstract

Changes in fine structure of chick liver cells throughout an embryogenic development are studied on light and electron-microscopy with the following results.1. Formation of the liver cell-cords and the bile canalicules begins about 6th incubation day. Then the vascular net work rapidly develops resulting a completion of whole liver organization hitologically on about 14th incubation day. The hemopoietic function and KUPFFER's cell's phagocytic function (phagocytosis) are active at this period.2. Only a small dose of glycogen is observed on the 6th incubation day partially in the liver cell's. It increases about the 16th incubation day, and a considerable increase is observed before the chick comes out of shell. But there follows a rapid decrease again.3. In chick fetus liver cell's fat develops slightly later than glycogen. The fat increases day after day and fills at the end of fetal period the cell together with glycogen. After the chick comes out of shell the liver cell contains still fat in quantities. The fat is at first small particles of lipoid nature, which gradually turn to droplets of neutral fat.4. Mitochondria in the liver cells are granular at the initial stage of fetal period, becoming rods and threads at the middle stage, then again granular at the final stage. The initial granula are primary forms, and the latter granula are assumed, on the basis of investigations on many intermediat forms to be related with a formation of paraplasm. The aforesaid morphological changes of mitochondria are observed in the electron-microscope. The middle layer of the cristae is wider at the final stage of fetal period.5. The endoplasmic reticulum initially appears vesicular. In the middle stage the vesicle type is gradually replaced by a flat and plate ones. At the final stage, they split through cleavage to form vesicles which increase after the hatching.