PLATE 1 
EXPLANATION OF FIGURES 
1 Froma photograph of a portion of a transverse section of the caudal fourth 
of the thyroid gland showing the left ultimobranchial body (U.). The colloid 
in the thyroid gland is represented by black dots. Froma pig7.5 days old. X 60. 
2 From a photograph of a portion of a transverse section of the caudal half 
of the thyroid gland showing the more anteriorly located segment of the right 
ultimobranchial body (U.). The white spots in the thyroid gland represent 
follicles out of which the colloid has dropped. From a pig 15 days old. X 60. 
3. From a photograph of a portion of a transverse section through the caudal 
fourth of the thyroid gland showing the left ultimobranchial body (U.). From 
pig 42 days old. X 60. 
4 From a photograph of a portion of a transverse section of the posterior 
fourth of the thyroid gland showing the right ultimobranchial body (U.?) and 
two very large (cystoid) follicles (C.F.) which are filled with colloid. From 
young adult hog no. 1. X 45. 
ABBREVIATIONS 
C.F., eystoid follicle; 7., thyroid; U., ultimobranchial body 
