Electron microscopic observations of alveoli development and epithelial diff erentiation in the fetal lung of the Chinese

Abstract

Abstract: Objective To observe the development of the a lv eoli and the differentiation of the epithelium in the fetal lung of Chinese.Methods Chinese human lung tissues were obtained from 20 fetuses of 10 to 34 weeks old, and the ultrastructural changes of the alveolar epithelial cells were obs erved using both optical and transmission electron microscope.Results At the f irst 10 to 16 weeks of development, the lung showed a tubular structure, the epi thelial cells were columnar and poorly differ-entiated. At weeks 17 to 24, the b ronchioles increased and the epithelial cells were differentiated to approach ma turity. A few lamellar bodies were observed in the cuboidal lining cells with t he majority being type Ⅱalveolar cells at 25 weeks, when the primitive alveola r was formed. In this stage many primitive epithelial cells could be seen, which appeared primordial in form before evolving into type Ⅱand typeⅠcells and pe rhaps served as epithelial stem cells or progenitor cells. From about 26 weeks, type Ⅰcells were observed but most of the epithelial cells were type Ⅱcells. Type Ⅰcells began to increase in the alveolar epithelium until 32 weeks.Conclusions The alveolar type Ⅱcells and type Ⅰcells are probably both derived from the same precursor cells or stem cells, and no evidence has shown that type Ⅱ cells may differentiate into type Ⅰcells during the development of the fetal l ung.

CLC Number:

R562.25

KONG Xiang-yong¹, AN Jing², FENG Zhi-chun¹. Electron microscopic observations of alveoli development and epithelial diff erentiation in the fetal lung of the Chinese[J]. Journal of Southern Medical University, 2004, 24(01): 72-74,78.

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