24 PRINCIPLES OF VETERINARY SURGERY 



younger cells and direct antecedents of the more matured 

 fibroblasts. These formative cells have received various 

 names depending upon the kind of mature tissue they are 

 intended to form — if fibrous tissue, fibroblasts; if cartilage, 

 chondroblasts; and if bone, osteoblasts. As they continue 

 proliferating, the old fibrous intercellular substance disap- 

 pears and the new tissue becomes soft and yielding like em- 

 bryonal tissue. The cells often overlie one another and may 

 exhibit an "epithelioid" arrangement. As soon as the defect 

 in the tissue has been made good, the fibroblasts begin se- 

 creting and storing a stroma-forming substance and their 

 protoplasmic processes break up into small fibrils. Ultimately 

 their cell bodies do likewise, forming small bundles of fibrils 

 arranged in parallel rows. They thus lose the greater part 

 of their protoplasm and finally return to the adult form of 

 connective tissue cell, the small narrow cell with a dark 

 spindle-shaped nucleus. The intercellular substance be- 

 comes more fibrous and the new tissue grad'ually approxi- 

 mates that of normal tendon, fascia, skin or whatever the 

 form of connective tissue may be. 



The method of repair varies somewhat according to 

 whether a blood clot is or is not present in the wound. After 

 division of a tendon, if no blood-clot be present, the sheath 

 simply collapses, becomes adherent to the tendon stump and 

 new tissue immediately is formed by the cells of the sheath 

 and cut tendon. When a blood-clot is present, the method of 

 repair is not so simple. Large numbers of leucocytes first in- 

 filtrate the clot and the ends of the cut tendon degenerate, 

 becoming soft and succulent. But in a few days, the cells 

 of the sheath and tendon begin to proliferate, new capillaries 

 are formed and a mass of granulation tissue replaces the 

 clot, extending some distance into the ends of the tendon. 

 Eventually the new vessels in the granulations join those of 

 the tendon, the embryonal cells develop into the adult form, 



