Fetal wound healing proceeds without fibrosis or scar formation in con
trast to adult wound healing. The mechanisms responsible for this rema
rkable process are mediated in part through a fetal wound extracellula
r matrix rich in hyaluronic acid (HA). Polyvinylalcohol sponge (PVA) w
ound implants were placed pervertebrally at 24 days' gestation in feta
l (N = 118) rabbits and in adult (N = 44) rabbits, and then harvested
at 1, 2, 3, 4, 5, and 7 days postwounding. To analyze-the fetal and ad
ult wound matrix, the HA concentration of wound fluid within the PVA s
ponge was quantitated using a-newly developed assay. A significantly i
ncreased (P < .05) HA deposition on days 1 through 7 in the fetal woun
ds was found compared with the adult wound. These observations may sug
gest an important physiologic role in fetal wound healing by providing
a more fluid and malleable matrix. These results, coupled with earlie
r findings of the lack of an acute inflammatory response in the fetus,
further support the hypothesis that fetal response to injury is signi
ficantly different from adult response in this prescience of an implan
ted PVA sponge. Copyright (C) 1997 by W.B. Saunders Company