Browsing by Subject "Lung development"

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    Morphological and molecular aspects of lung development
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2025) Schmiedl, Andreas; Mühlfeld, Christian
    Healthy breathing relies on normal morphological and functional development of the lung. This includes different prenatal and postnatal developmental stages. Depending on species and postnatal behavior as nest escapers or nest squatters, the duration of individual developmental phases and the state of differentiation of the lungs at birth differ. However, the sequence and morphology of the lung developmental stages are similar in all mammals, so knowledge gained from animal models about development-specific genetic control and regulatory mechanisms can be translated in principle to the human lung. Functional lung development comprises the maturation of the surfactant system, which is closely linked to the morphological development of the pulmonary acini. Although a number of reviews are found in the literature, a presentation that integrates the morphological and molecular regulatory mechanisms is missing. Therefore, the aim of this article was to provide an up-to-date comprehensive review of the main morphological steps and regulatory mechanisms of lung development, including clinical aspects related to developmental disorders.
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    Time-dependent effects of maternal continuous propranolol on fetal lung development in rats
    (Murcia : F. Hernández, 2002) Smith, Dennis M.; Sommers Smith, Sally K.
    Previous studies have demonstrated a role for the beta-adrenergic system in the maturation of the fetal alveolar epithelium. Chronic blockade of beta-adrenergic binding sites has been shown to adversely ef f e c t p hysiologic and biochemical indices of fetal lung maturation. In the present study timed-pregnant female Sprague-Dawley rats were treated with a continuous 0.5 mg/hr dose of propranolol HCl, or saline, via an osmotic pump. The treatment periods were days 18-21, or 20-23 of gestation. Fetal body weights were obtained, and the morphology of the fetal lungs studied by light and electron microscopy. Cytoplasmic volume densities of lamellar inclusion bodies and glycogen within d eveloping type II alveolar epithelial cells were also determined. In addition, total phospholipids (as phosphorus) and glycogen content were determined b i o c h e m i c a l l y. The fetuses from females treated from day 20-23 demonstrated no differences between salinetreated and propranolol-treated groups, in either fetal weight or the morphologic appearance of the developing lung. In contrast, the fetuses from mothers treated from day 18-21 with propranolol were significantly smaller, and their lungs appeared less mature than saline-treated counterparts. The glycogen content of developing type II alveolar epithelial cells was significantly more abundant (as judged by stereologic and biochemical analyses) in the propranolol-treated fetuses. In addition, total phospholipids were decreased in the propranolol-treated 21-day fetuses. The results of the present study suggest that the development of the alveolar epithelium is s e n s i t ive to continuous beta-adrenergic blockade by propranolol during a critical time late in gestation.