[Various mechanisms of reducing the vascular system of granulation tissue in the process of its maturation]

Rat granulation tissues were histologically and electron radioautographically examined at Days 7, 20, 30, 40, 53, and 60 after making a 3 X 4-cm2 wound in the back. During the entire period of cicatrization, alterations were shown to occur in the capillaries, as manifested by destructive changes in endotheliocytes, break in their contacts, thinning of the capillary wall with occasional lacerations, disintegrity of the basal membrane and, finally, vessel-composing cell dissociation and departure, as well as unusual arrangement among other cells and fibrous structures. On the basis of the findings it is proposed that the known diminished numbers of vessels during granulation tissue maturation involves not only disappeared vessels due to their progressive dystrophic changes, but the described unusual capillary alterations whereby the vascular wall cells are gradually converted to the cellular elements freely located in the interstitial tissue.