424 



EDGAR H. NORMS 



the cells of the plate (fig. 3). The cell outlmes can be made 

 out only with difficulty in most cases. But in those places 

 where they can be seen, they bound cells which are more or less 

 columnar in form. The nuclei are ovoidal or elliptical in out- 

 line and are placed with their long axes perpendicular to the sur- 

 face of the plate. Here and there along the course of the plate 

 (fig. 3) it will be noticed that some of the nuclei have shifted 

 their axes and have changed their relative positions. Certain of 

 the nuclei have rotated through an arc of 90 degrees so that their 



Foil. 



Mes. 



Fig. 2 Semi-diagrammatic drawing (camera lucida outlines) of a section 

 through the right lateral lobe of the thyroid gland and neighboring structures 

 of a human fetus 30 mm. long (No. 30). Shows epithelial plates developing 

 rough surfaces; also early follicles in various stages of separation from the plates. 

 Note the general increase in width of the plates as compared with those shown 

 in figure 1, and the swellings and constrictions, giving 'beaded chain' appearance. 

 Cap., capillary; Fol.L., follicle limaen; S.Ep.PL, smooth epithelial plate ; 

 R.Ep.Pl., rough epithelial plate; Mes., mesenchyme; C, cartilage; L., larynx. 

 X 133. 



