Morphometric study of the plasmalemmal vesicles of the capillaries of the rat cerebellum, heart, diaphragm and lung during perinatal growth.
1. Morphometric techniques were used to determine the variation in number of plasmalemmal vesicles, their area and the area of the endothelium in capillaries of the cerebellum, heart, diaphragm and lung of rat fetuses aged 17, 19, 20 and 21 days and of newborn rats. 2. A curve fitting procedure showed that the evolution of vesicle number could be properly expressed by equations of the type ŷ = aoekx, where ŷ = number of vesicle images per capillary section or number of vesicles per micron3 of capillary wall, and x = age in days. The time necessary for the numerical density of the vesicles to duplicate in the capillary wall is on average 1.1-1.3 days in the lung, 1.4-1.9 days in the muscular organs and 2.3 days in the cerebellum. 3. Capillary maturation was characterized by thinning of the endothelium, especially for those at the base of the lung, and by increased numbers of vesicles. 4. The ratios: number of plasmalemmal vesicle images/endothelial area, plasmalemmal vesicle image area/endothelial area, and number of plasmalemmal vesicle images/plasmalemmal image area increased with age. The third parameter tended to reach 1 due to the increased area of the vesicles as a function of their numbers, even though there was a decrease in individual vesicle size.
Departamento de Morfologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Brasil.
P A
PA
Padovan
I P
IP
Padovan
A R
AR
Cruz
D000818:Animals; D002196:Capillaries / Q000648:ultrastructure; D002531:Cerebellum / Q000098:blood supply; D003331:Coronary Vessels; D003964:Diaphragm / Q000098:blood supply; D004730:Endothelium, Vascular / Q000196:embryology / Q000648:ultrastructure*; D005260:Female; D008168:Lung / Q000098:blood supply; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains