The study of methyluracil induction action on osteogenesis raised a qu
estion of the reacting system. In rabbit isolated system experiments t
he stages of blood clot transformations were investigated in standard
conditions in vivo and under methyluracil phonophoresis, using diffuse
cameras. The contents of the cameras underwent macroscopical, histolo
gical and electron-microscopical examinations throughout 3 months. The
findings suggest tentative conclusions on the existence in the periph
eral blood of connective tissue precursors with strong proliferative p
roperties and differential potential including cells inducible to oste
ogenesis.