ABSTRACT
Background: The interaction between the mesenchyme and epithelium is required for the normal differentiation of fetal lung tissue. The morphogenic interaction may be mediated by changes in the composition and structure of the extracellular matrix .
Aim of the work: to examine the distribution of fibronectin and laminin in the prenatal and postnatal mice lung tissue.
Materials and Methods: This study was conducted on samples of 6 groupes, 4 prenatal [14,16, 19,and 21days] and two postnatal [3 and 7 days] mice lung tissue. Histological and immunohistochemical methods using H & E, fibronectin and laminin antibodies were performed.
Results: the present work showed many stages during differentiation of the lung that starts as pseudo-glandular stage (14 day) followed by the canalicular stage (16-21 day) which is formed by epithelial cell buds and the surrounding invaded mesenchyme. Smooth muscles of the blood vessels, bronchi and bronchioles are well developed from the surrounding mesenchyme by the 19th prenatal day.
Fibronectin immunoreactivity was variable in the cell membrane of epithelial cells lining bronchioles, while it was more evident in the cytoplasm and cell membrane of the mesenchymal cells and vascular endothelial cells in the prenatal group to reach its peak before birth and gradually decreased after birth.
Laminin immunoreactivity was also variable in the apical and basal cell membranes of epithelial cells lining bronchioles. This immunoreactivity became stronger and localized to the basal membrane as the development proceeded and became more evident in the cytoplasm and cell membrane of the endothelial cells to increase gradually prenataly then declined after birth.
Conclusion: Fibronection and laminin are important markers for indicating the development of lung stroma and parenchyma , where their immuoreactivity increased gradually during the prenatal period in the cell membranes of epithelial cells lining bronchi, bronchioles, alveoli, endothelial and mesenchymal cells which is more evident basally for laminin. Both fibronectin and laminin play an important role in development of mature lung structure as they were gradually decreased in the postnatal period.
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