The morphology and morphometric data of collagen and elastin fibers in the pulmonary alveolar walls are presented. Specimens were obtained from postmortem lungs quick-frozen at specified transpulmonary pressures. Collagen was stained by silver, and elastin was stained by orcein. Photomicrographs were composed by computer. Young lungs typically show small collagen fibers that radiate from the "posts," whereas larger fiber bundles traverse the septum irrespective of capillary blood vessels. In older lungs, rings of collagen around the posts appear enlarged. Elastin bundles do not show obvious variation in pattern with age and inflation pressure. Statistical frequency distributions of the fiber width and curvature are both skewed, but the square root of the width and the cube root of the curvature have approximate normal distributions. Typically, for young lungs at transpulmonary pressure of 4 cmH2O, the mean of (width)1/2 (in micron1/2) for collagen fibers is 0.952 +/- 0.242 (SD), that of (curvature)1/3 (in micron-1/3) is 0.349 +/- 0.094. The corresponding values for elastin are 0.986 +/- 0.255 and 0.395 +/- 0.094.
Morphometic data of the pulmonary artery in the cat's right lung are presented. Silicone elastomer casts of cat's right lung were made, and measured, counted and analyzed. The Strahler system is used to describe the branching pattern of the arterial vascular tree. These data are needed for any quantitative approach to the study of the pulmonary circulation. For all the pulmonary blood vessels of the cat lying between the main pulmonary artery and the capillary beds, there are a total of 10 orders of vessels in the right upper lobe, 9 orders of vessels in the right middle lobe and 11 orders of vessels in the right lower lobe. The ratio of the number of branches in successive orders of vessels or the branching ratio, is 3.58. The corresponding average diameter ratio is 1.72, whereas the average length ratio is 1.81.
After 1 h of exposure to 0.5 atm of pressure, the electron microscopy of intra-acinar arterioles of the young female adult rat showed edema and subendothelial blebs. Pulmonary hypertension developed rapidly with an increase in hemoglobin, hematocrit, and right ventricular weight. By 24 h, there was a threefold increase in the number of fibroblasts within the arteriolar wall, followed during the next 2 days by transformation of the fibroblast through a transitional cell form to a smooth muscle cell. By 1 wk, the neomuscularization was essentially complete. There was further minor thickening and increase in density of the wall over the next 9 mo. On return to 1 atm after prolonged hypoxia, within 4 wk, the smooth muscle of neomuscularized arterioles dedifferentiated but did not disappear. There was a concurrent rapid fall in the pulmonary arterial pressure, hemoglobin, hematocrit, and right ventricular weight. Veins, capillaries, and arteries remained normal. Parallel studies in the male rat during 14 days of hypoxia demonstrated the same phenomena except slightly accelerated over the female. The rapid sequential changes in the arteriole, beginning with subendothelial blebs and wall edema, followed by fibroblast recruitment and transformation into smooth muscle through a transitional cell form, suggest a cascade. The anatomic and physiological responses to hypoxia are not sex related.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.