Biochemical Analysis of Granulation Tissue in Bipedicle Tube Flaps: An Experimental Study

Abstract

The concentration of collagen, RNA and DNA was measured in 2 to 8 week old granulation tissue collected from steel wire mesh cylinders implanted in bipedicle tube flaps. Granulation tissue collected from cylinders implanted in skin folds was used as control. Up to weeks 3 and 4 the concentration of collagen increased. The pattern was similar in the skin flap and the skin fold groups, except for a higher concentration of collagen in the controls at week 4. The cell density, as measured by DNA, was high in both groups at week 2 and then decreased. RNA was also high at week 2 and then fell similarly in the two groups. Between weeks 4 and 6 the collagen decreased in concentration as well as total amount in both groups, indicating that the degradation of collagen exceeded its synthesis during this period. In the control group the cell density at weeks 5 and 6 was increased and the activity of acid phosphatase and β-glucuronidase showed a peak at week 5. These findings were interpreted as an invasion of macrophages containing lysosomal enzymes involved in the resorption of collagen. Granulation tissue development was thus largely equal in the skin flap and control groups with a period of fibroblasia up to week 4 and a period characterised by decrease in the amount of collagen between weeks 4 and 6. The latter phase may be related to the maturation of flaps.