AGE-DEPENDENT CHANGES IN PREVALENCE, SIZE AND PROLIFERATION OF ARTERIAL LESIONS IN COCKERELS .1. SPONTANEOUS LESIONS

  • 1 January 1980
    • journal article
    • research article
    • Vol. 7  (6) , 448-463
Abstract
Age-dependent changes were determined in the prevalence, size and proliferation of early spontaneous aortic lesions in White Leghorn cockerels. Groups of 6 animals received weekly i.m. injections of dimethyl sulfoxide (DMSO) or remained uninjected. They were sacrificed at 6, 8, 12, 16, 20 and 38 wk of age. Lesions were observed microscopically in all animals 8 wk of age and older. They appeared in 20-30% of the aortic segments until 16 wk of age and in 60% of the segments thereafter. The presence of a long single lesion along the aortic length was revealed by sectioning serially, at 50-.mu.m intervals, 10- to 20-mm lengths of lesion-containing aorta. Between 8 and 20 wk of age, lesion cross-sectional area increased by a factor of 2.4 while lesion volume index increased by a factor of 6. Similar patterns of proliferation were observed at each time point between lesion cells and those in the underlying media. Labeling indices of media and lesion cells were highest when the animals were growing rapidly and lowest when the animals reached full size. Spontaneous lesions increase in depth and extend radially at a low constant level at 8-20 wk of age and increase markedly in length at 16-20 wk. Lesion cell proliferation is sufficient to account for the observed increase in lesion size and proliferation of lesion cells and medial cells may be governed by the same control mechanism(s).