THE DEVELOPMENT OF THE ADRENALS IN THE 



TURTLE 



ALBERT KUNTZ 



From the Laboratories of Animal Biology of the State University of Iowa 



NINE FIGURES 



CONTENTS 



Introduction .• 71 



Observations 76 



Earlj' development 76 



Cortical substance 76 



Chromaffin substance 79 



Later development 81 



Genetic relationship and differentiation of chromaffin cells 85 



Summary 87 



Bibliography 88 



INTRODUCTION 



A review of the literature bearing on the development of the 

 adrenals in the several classes of vertebrates reveals several oppos- 

 ing theories of development each of which has been supported 

 by investigators of recognized ability. The adrenal system is 

 a compound system. In the lower vertebrates it includes (accord- 

 ing to the nomenclature proposed by Balfour) the interrenals 

 and the suprarenals. In the higher vertebrates these two sys- 

 tems are consolidated more or less completely into a single pair 

 of adrenal organs composed of the cortical substance which cor- 

 responds to the interrenals of the lower vertebrates, and the med- 

 ullary, or chromaffin, 1 substance which corresponds to the supra- 

 renals. These organs have been described by some investigators 



1 The term, chromaffin substance, will be used in this paper in preference to the 

 term, medullary substance. A true medulla occurs only in the adrenals of mam- 

 mals. 



71 



