출생 후 제대혈관 폐쇄에서의 세포고사 = The Role of Apoptosis in thc Closure of Human Umbilical Vessels at Birth and Its Mechanism

다국어 초록 (Multilingual Abstract)

Background: The mechanism of the closure of umbilical vessels is known to be multifactorial. In order to verify that apoptosis is one of the possible closure mechanisms, we studied to identify apoptosis in umbilical vessels and evaluate its mechanism by studying apoptosis-related gene and the relationship between the pattern of apoptosis and gestational age (GA). Methods: Twelve umbilical cords of GA of 37-42 weeks were obtained immediatly (less than 10 min. for minimal ongoing external influences) after birth. The presence of apoptotic cells was demonstrated by electron microscopy (EM) and terminal deoxynucleotidyl transferasemediated dUTP nick end labeling (TUNEL). Immnohistochemical staining and Western blotting were used for the analysis of the proteins of apoptosis-related gene. Results: Apoptosis of the smooth muscle cells of media and intima of umbilical vessels was identified at EM, regardless of GA from 37 to 42 weeks. The proportion of TUNEL(+) cells was 80% in intima, 40% in media, 80% in connective tissue of umbilical cord. The expressions of bax-a, bcl-Xs/L were strong in intima, in media and connective tissue, but those of bcl-2 were detected in only in connective tissue, regardless of GA in immunohistochemistry. The ratios of expressions of bax- a to bc1-2, bcl-Xs to bcl-XL, did not change with increasing GA from 37 to 42 weeks in Western blot- ting. Conclusion: Apoptosis was identified in umbilical vessels. The closure of umbilical vessels can be explained by apoptosis where the ratios of bax-a/bcl-2, bcl-Xs/ bcl-XL play an important role. The fact that there were no differences in the extent of apoptosis and the expressions of bax-a/bcl-2, bcl-Xs/bcl-XL according to GA, suggests that apoptosis of umbilical vessels is more dependent on the external stimuli during delivery than GA.