Apoptosis in Rat Liver Development: tTG and TGF beta1 Expression Related to Apoptotic Mechanism / 대한해부학회지

This study was designed to investigate the apoptosis and the roles of TGF beta1 and tTG in apoptosis in fetal and postnatal rat livers using TUNEL and immunohistochemical staining. Results obtained were as follows: 1. Apoptosis began to appear in gestation day 15, reached the peak in gestation day 16 showing the highest activity of hepatic hemopoiesis, and gradually decreased after gestation day 18. But apoptosis repeatedly increased after postnatal day 1. 2. The cells showing apoptosis were mainly hemopoietic cells during gestation period, but were mainly hepatocytes after birth. In addition, apoptosis increased in sinusoidal endothelial cells after birth. 3. Apoptotic bodies rarely appeared in gestation day 16, increased in gestation day 18, and partly decreased after gestation day 20. Thereafter, the frequency of apoptotic bodies was relatively constant untill postnatal day 10. 4. TGF b1 began to be expressed from gestation day 14 when apoptosis occurred, was strongly expressed from gestation day 16, and became to be expressed weakly after gestation day 18. The expression of TGF beta1 was increased in sinusoidal endothelial cells after birth. 5. tTG began to be expressed in gestation day 16 during the highest activity of hemopoietic stage, and became to be expressed weakly in apoptotic bodies after gestation day 18. The expression of tTG increased again mainly in sinusoidal endothelial cells after birth. In summary, it is suggested that apoptosis is related to the control of hemopoiesis in prenatal period and the maintenance of the physiological balance of hepatic tissue after birth, and that TGF beta1 is related to the induction of the apoptosis during liver development and to the formation of apoptotic bodies through the control of the expression of tTG.

Expression pattern of transforming growth factors observed immunohistochemically in fetal rat / 대한해부학회지

The roles of TGF-beta1, beta2 and beta3 according to gestational ages and histodifferentiation were studied using immunohistochemistry with rat fetuses. 1. From day 14 to 21 of fetal rat, all the TGF-beta1, beta2 and beta3 were expressed in endocardium, myocardium, bronchiole, tunica intima of blood vessles, mucosa and serosa of intestine, striated muscle, hepatic capsule, hepatic hemopoietic cells, meninges, epidermis and dermis. 2. From day 14 to 21 of fetal rat, TGF-beta1 was not expressed in the smooth muscle of blood vessel and intestinal tract, alveolar cell and renal tubular cell. TGF-beta2 was not expressed in the smooth muscle of blood vessel and intestinal tract and alveolar cell. TGF-beta3 was not expressed in osteocyte, alveolar cell, and basement membrane of renal cuboidal epithelial cell. And TGF-betas expressed especially in early or late gestational age and the degree of expression increased or decreased with gestational age. 3. The TGF-beta1, beta2 and beta3 were expressed in tissues originated from 3 germ layers except several tissues, and those originated from mesoderm exhibited strong expression. The TGF-beta1 was expressed more widely than TGF-beta2 and beta3 during gestation. In summary, TGF-beta1, beta2 and beta3 were considered as important control factors of cell to cell interaction in the morphogenesis of tissues during fetal development.