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KMID : 0381919990290030291
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Korean Journal of Microscopy
1999 Volume.29 No. 3 p.291 ~ p.301
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The Differentiation and Ultrastructural Characteristics of Type II Pneumocyte in Early Human Fetal Lungs
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Yoo Dong-Hwa
Kim Dae-Joong
Kim Sung-Su
Kim Kyung-Yong
Lee Won-Bok
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Abstract
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The differentiation and ultrastructural characteristics of type II pneumocyte was investigated using 7 cases of human fetal lungs from 9 to 20 weeks of gestation by transmission electron micropscopy. The result obtained were as follows. 1. From the pattern of epithelium, type II pneumocyte was not discernable, but with the gradual development of gestation, the epithelium of the future pulmonary alveoli was transformed from pseudostratified columnar into simple cuboidal epithelium after 15 weeks of geatation. 2. The multilamellar body very specific to type II pneumocyte was observed at first at 9 weeks of gestation. Besides, another characteristics of the cell were also observed such as cytoplasmic inclusion body, granular inclusionbody,multivesicularinclusionbodyanddensebody. 3. The number and size of multilamellar body increased, but those of other inclision bodies decreased at 19 and 20 weeks of gestation. In summary, type II pneumocytes (or precursor cells) with multilamellar body and another characteristic inclusion bodies were observed in the human fetal lungs from 9 weeks of gestation. And so, it is suggested that the differentiation of type II pneumocyte starts at or before 9 weeks of gestation.
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KEYWORD
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Lung, Type II pneumocyte, Ultrastructure
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