412 EDGAR H. NOREIS 



II. LITERATURE 



The literature concerning the thyroid follicle will be consid- 

 ered in chronological order. First, it is desirable to mention 

 briefly the various views which have been held concerning the 

 morphology of the adult (human) thyroid follicle. Then fol- 

 lows a brief statement of the conclusions concerning follicle de- 

 velopment (including also prefollicular stages), which have been 

 arrived at by the observers who have worked upon human ma- 

 terial. A few observations, made on lower forms, which have 

 seemed especially pertinent to the present problem, are also in- 

 cluded. Unless otherwise indicated, however, all statements 

 fefer to human material. 



The follicular structure of the adult human thyroid gland has 

 long been known. According to Boechat ('73), Lalouette (1750), 

 who was the first to describe the minute structure of the thyroid 

 gland, found vesicles which seemed to communicate with each 

 other. Bardeleben ('41) is said by Zeiss ('77) to have been the 

 first to describe the adult thyroid foUicles as isolated structures. 

 Five years earlier, however, Jones ('36) described the thyroid 

 follicles in considerable detail as completely closed vesicles. 

 Although there has been considerable disagreement concerning 

 the structure of the adult thyroid follicle, the majority of the 

 later observers have, like Jones, described the vesicles of the 

 adult gland as closed, spheroidal bodies. Cruveilhier ('43), 

 Virchow ('63), and more recently Boechat ('73), Zeiss ('77), and 

 Hitzig ('94), however, have followed Lalouette in describing 

 the follicles as forming a system of branched and conmiunicat- 

 ing cavities "within the gland. Still others, like Streiff ('97), 

 have maintained that both branching forms and isolated vesicles 

 occur in the adult gland. 



Jones ('36), who was perhaps the first to describe the micro- 

 scopic structure of the human fetal thyroid, found that in a fetus 

 of four and one-half months the cells of the gland had become 

 partially arranged into solid, globular masses; but no vesicles 

 were observed at this stage. 



