The effects of intrauterine pneumonectomy in lambs. A morphometric study of the remaining lung at term.
A morphometric study was made of the remaining lung of term lambs that had undergone left pneumonectomy at 60, 80, 100, or 120 days gestation. All pneumonectomy lambs showed some compensatory growth since right lung volume to body weight ratio was higher in all lambs after pneumonectomy than in term controls. In 3 lambs operated at 80, 100, and 120 days, respectively, however, compensatory volume increase was more complete than in the other lamb of each age pair or the 2 lambs operated at 60 days. Despite individual variation, the potential for compensatory lung growth seems greater in the canalicular and later stages than in the pseudoglandular. Measurements indicating distal air-space size (volume density of alveoli, volume density of alveolar duct, surface density of alveolar epithelium, numerical density of alveoli, and mean linear intercept) were similar in all animals, but total alveolar surface area and number increased proportionally to lung volume. The fact that the remaining lung compensates by increasing alveolar number rather than by enlarging air spaces is a model of human developmental abnormalities in which the alveolar number at birth is greater than normal (polyalveolar). At the intraacinar level, a higher than normal proportion of muscularized arteries was found in lambs operated early in gestation and in lambs with smaller compensatory lung growth: an inverse relationship was seen--the lower the lung volume the higher the proportion of muscular arteries. The cause for this is unknown, but may result from the relatively increased flow to a vascular bed smaller than that of two normal lungs.
D000792:Angiography; D000818:Animals; D001835:Body Weight; D005333:Fetus / Q000601:surgery*; D008168:Lung / Q000033:anatomy & histology / Q000196:embryology* / Q000601:surgery; D008176:Lung Volume Measurements; D011651:Pulmonary Artery / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D012119:Respiration; D013909:Thorax / Q000033:anatomy & histology