<正> The present study has been carried out in 10 dogs

in which fibronectinin wound fluid and plasma was measured with single radial immunodiffusion.Fibronectin in wound fluid rose from 24 h to 7 d after fracture.The meanincrease of fibronectin level was 0.79（P>0.01）

1.76（P<0.01）

3.07（P<0.001）and4.82（P<0.01）fold at 48

72 h

5 and 7 d

respectively

as comparison with 24 hafter fracture.Plasma fibronectin levels were markedly reduced 6 to 72 h afterfracture.The mean decline was 19.2％（P<0.01）

18.0％（P<0.01）

28.0％（P<0.01）and 9.2％（P<0.05）at 6

24

48 and 72 h

respectively.To our knowledge

therehas been no report on the regularity of the changes of fibronectin in wound fluidbefore

and a close correlation（r=0.9986;P<0.001） between the increase offibronectin levels and wound healing.A hypothesis

based on our study andcurrent literature

is presented that the increase of fibronectin in extracellularenvironment and the loss on cellular surface initiate

control and regulate themain biologic process of wound healing.