8. Findings in pericardial pore formarmation

I have described the pericardial pores which communicate the pericardial cavity with pleural cavities. In order to investigate the formative process of the pores, the pericardium of the ddY mice from birth to 21 days was examined. Up to 6-7 postnatal days, the mice pericardiunl consisted of the mesothelial cell layer of the parietal pericardium, the mesothelial cell layer of the parietal pleura and the connective tissue sandwiched between them. Abundant pericardial pores made their appearance at 10-20 days after birth, cell processes from the mesothelial cells of one side towards those of another side developed to form cellular junctions connecting from the side developed to form cellular junctions connect heart side to the lung side. As a result. pericardium made tongue-like processes connected with each other at the tips. When the junctional contact of the processes separated. the pericardial pores were produced.