246 Regeneration. 



measure ; at least microscopically proliferation of remnants of nu- 

 cleated sarcoplasm may be observed, whole chains or rows of new 

 nuclei being produced b}- direct nuclear division, these in asso- 

 ciation with proliferation of the sarcoplasm by longitudinal divis- 

 ion going to form the so-called muscle cylinders (\\'aldeyerj and 

 lateral olT-shoots known as muscle buds (Naumannj. Apparently 

 the sheath of the sarcolemma develops from the surrounding con- 

 nective tissue, which is also proliferating; and the developing sar- 

 coplasm takes on a fibrillar structure. In tramnatic lesions connec- 

 tive tissue formation predominates, the healing of the wound usually 

 giving rise not to the reconstruction of the contractile elements, 

 but to the formation of dense scars. 



Smooth muscle even in traumatic lesions exhibits active mitosis, 

 and multiplication of the muscle of the blood vessel walls is to be 

 observed in granulating tissue ; but in lesions of muscular tunics, 

 as of the stomach, intestine or uterus, complete restitutio ad inte- 

 grum has never been observed, scar formation taking place instead. 



Eegeneration of tendon tissue (studies of this process being 

 often afiforded in the rather common performance of tenotomy) 

 begins, according to Alarchand, principally from the loose cellular 

 tissue between the bundles of tendon fibrils. This formative ma- 

 terial, composed principally of spindle cells, develops (by mitosis) 

 into the cleft between the cut ends of the tendon, which is filled up 

 with blood or exudate, and unites the tendon stumps as a soft gray- 

 ish fibroplastic mass. Later the fibroblasts form a fibrillar matrix, 

 the fibrils arranged parallel with each other, and the tendon scar 

 gradually acquires great firmness. According to Paget a divided 

 tendon of Achilles of a rabbit may be found united as early as from 

 three to five days and in ten days may be of sufficient strength to 

 require a tensile force of twenty-eight pounds to tear it apart. 



Lesions of cartilage, as that of the air passages, the auricle, or 

 ribs, are restored by connective tissue formation from the perichon- 

 drium, the cells of which give origin to a fibrillar, collagenous sub- 

 stance. The latter may become homogeneous and by a metaplastic 

 process the connective tissue thickening be converted into hyaline 

 cartilage ; and it is possible that by an infiltration of calcareous 

 salts ossification of the embryonic tissue occupying the space of 

 the lesion may ensue. The cartilage itself takes no part in the 

 process of restoration and connective tissue scar formation is usually 

 but slight. 



New formation of osseous tissue after fractures and operative 

 lesions arises exclusively from the periosteum and bone marrow 



