34 PRINCIPLES of VETERINARY SURGERY 



division and also by karyokinesis), and ultimately push their 

 way over the gap in the tissue which has been filled up with 

 granulations. Comparatively few epithelial cells are requi- 

 site to cover defects that originally were very large, for the 

 contraction of the granulation-tissue lessens the superficial 

 area of the wound. 



The multiplication of cells takes takes place chiefly from 

 the deep layers of the rete Malpighii, but if the whole thick- 

 ness of the skin has not been destroyed, the epithelial cells of 

 remnants of glands and hair-follicles may give rise to the new 

 epithelium, little islets of new epithelium being scattered 

 over the granulating surface, a so-called "insular" epider- 

 mization., 



Cylindrical epithelium is usually accompanied by a 

 change of form when regenerating. The new cells are lower 

 and more squamous in form, but later assume their riorrnal 

 shape. In the intestine, the surface cells are replaced by 

 proliferation of the cells in Lieberkiihn's glands. 



The appendages of the skin, the hoofs and hair, are re- 

 stored if suf^cient portions of the matrix or root remain from 

 which the new tissues may grow. In large wounds of the 

 skin which heal with a cicatrix, the hair and glands are not 

 restored. 



As regards the regenerative power of the glandular epi- 

 thelium, opposite conclusions have been drawn by various 

 investigators, some claiming that glands will readily repair 

 their parenchyma, while others directly deny this. Experi- 

 ments with lower animals seem to confirm the first conclu- 

 sion, while practical experience suggests the opposite as the 

 more usual result. According to Diirck, true regeneration 

 of glandular substance capable of functionating probably 

 never takes place. The reparative process consists in simple 

 scar-formation when a liver, kidney, ovary or testicle is to be 

 healed. The cicatricial tissue varies slightly in the different 



