AUTHOR 8 ABSTRACT OF THIS PAPER ISSUED 

 BY THE BIBLIOGRAPHIC SERVICE, APRIL 11 



STUDIES IN THE DYNAMICS OF HISTOGENESIS 



IV. TENSION OF DIFFEKENTIAL GROWTH AS A STIMULUS TO MYO- 

 GENESIS IN THE LIMB 



V. COMPRESSION BETWEEN THE ACCELERATED GROWTH CENTERS 

 OF THE SEGMENTAL SKELETON AS A STIMULUS TO JOINT 

 FORMATION 



VI. RESISTANCES TO SKELETAL GROWTH AS STIMULI TO CHONDRO- 

 GENESIS AND OSTEOGENESIS 



EBEN J. CAREY 



Marquette University Medical School, Department of Anatomy, Milwaukee, Wisconsin 



NINE FIGURES 



1. INTRODUCTION 



The writer has presented facts ('19-'20 a; '20 b) which prove 

 that the elongation of the developing muscular fasciculi of the 

 digestive tract is in the direction of a dominant growth mechani- 

 cal-energy extrinsic to the zone of myogenesis. This elongation 

 is dependent on the fact that the primitive gut presents two 

 zones of differential rates of growth. The inner epithelial tube 

 is accelerated in growth, as compared with the outer splanchnic 

 mesenchymal tube, which is retarded in growth. The growth 

 of the inner tube is after the mode of a left-handed spiral, and 

 is at first relatively more rapid in diameter than in length. The 

 inevitable mechanical resultant of this differential growth is a 

 tension of the outer tube in the same direction as the growth of 

 the inner one. The inner close spiral muscle coat of the colon, 

 in embryos of 14-25 mm. in length, begins to form during this 

 initial transversely accelerated growth of the epithelial tube. 



This initial muscle coat reacts upon the epithelial tube, thus 

 restricting growth in diameter. This resistance causes the inner 



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