Caracterização histológica do desenvolvimento hepático em diferentes estágios embrionários de ratos

Abstract

The rats have embryonic development similar to other domestic animals and human beings, thus a valid model for scientific studies. Among them, the F344 stands out for be isogenic, facilitating the reading of the results obtained because of their genetic homogeneity. Due to the lack of histological studies concerning hepatic development in rats, the present study aimed to characterize histologically for the first time the process of developing liver in the stages of gestation of E12.5 (12.5 days of gestation), E13.5, E14.5, E15.5 and E16.5 in rats F344. Five embryos of each embryonic stage were collected, fixed in Metacarn, embedded in Paraplast and then histological stains and histochemistry were performed. The hepatic bud of embryo among 12.5-14.5 days presented themselves a cluster of hepatoblasts still disorganized and surrounded by numerous nucleated blood precursor cells. It was observed that the hepatoblasts have a large nucleus basophilic with little cytoplasm. Sinusoids with erythroblasts and Kupffer cells also have been found. At 14.5 days it was observed the coexistence of hepatoblasts and hepatocytes. In the embryos with 15.5 days began the verify distinction between the cords of hepatocytes in formation limited by capillary sinusoids. Such cords began to converge for the present centrilobular veins. At 16.5 days the parenchymal architecture was nearer found in the adult liver, being the quantity of hepatocytes greater than hepatoblasts. During this gestation period the liver also had hematopoietic function. The study brings histologically the rats F344 hepatic development between 12.5-16.5 days, evidencing the cells that comprise each gestational period generating subsidies for future studies.