Type I and Type III Collagen Content of Healing Wounds in Fetal and Adult Rats

TLDR

The study compared collagen composition in granulation tissue from full‑thickness dermal wounds in fetal (day 17) and adult rats, extracting collagen from tissues harvested at 2 days and up to 30 days, respectively, and quantifying type III to type I ratios by densitometry of electrophoretically separated α‑chains. Both fetal and adult granulation tissues had elevated type III collagen, but fetal tissue exhibited a markedly higher type III content than normal adult tissue.

Abstract

Full-thickness, dermal wounds were surgically created on the dorsa of fetal rats on the 17th day of gestation. The granulation tissue which developed after 2 days (19 days of gestation) was harvested from six to nine animals and pooled and the collagen was extracted with 0.5 M acetic acid and acetic acid plus pepsin. The ratio of type III:type I collagen was estimated from densitometer scans of electrophoretically separated α-chains. Full-thickness (to fascia depth) wounds were also produced on the dorsa of adult rats and granulation tissue which had developed for different periods of time up to 30 days was excised. Relative proportions of type III and type I collagen were assessed in normal and granulation tissues taken from the adult rats. Both fetal and adult granulation tissues have elevated type III collagen content but normal fetal tissue has a much higher content of type III than does normal adult tissue.