THE MORPHOGENESIS OF THE FOLLICLES IN THE 

 HUMAN THYROID GLAND 



EDGAR H. NORRIS 



Institute of Anatomy, University of Minnesota 



SEVENTEEN FIGURES 



CONTENTS 



I. Introduction 411 



II. Literature 412 



III. Material and methods 417* 



IV. Morphogenesis of the thyroid follicle 420 



a. Prefollicular period 420 



b. Follicular period , 423 



V. Discussion and conclusions 437 



VI. Summary 445 



VII. Literature cited 446 



I. INTRODUCTION 



In spite of numerous investigations, many questions concern- 

 ing the development of the thyroid gland are still unsettled. 

 This applies particularly to the morphogenesis of the thyroid 

 follicles. The various and contradictory views in the literature 

 on the development of the follicles are doubtless due in part to 

 lack of adequate series of successive embryonic stages (especially 

 of human embryos) available for study. The greatest difficulty, 

 however, has arisen from the use of inadequate methods of 

 investigation. The method hitherto almost exclusively used, 

 that of direct observation of the microscopic sections, is insuffi- 

 cient. By the use of reconstruction methods, however, it has 

 been found possible in the present study to reach a satisfactory 

 solution of this difficult and important problem, at least regard- 

 ing some of the more fundamental features. 



This study was undertaken in the Anatomical Laboratory of 

 the University of Minnesota at the suggestion of Prof. C. M. 

 Jackson, under whose supervision the work was conducted. I 

 wish to thank Dr. Jackson for his valuable aid and criticism. 



411 



