DEVELOPMENT OF THE HYPOPHYSIS 411 
Fig. 13 Left lateral view of a reconstruction of the hypophysis of a 22 mm. 
embryo. X 100. For abbreviations, see figure 12. 
In a model of a 28 mm. embryo (fig. 14) the entire anterior 
portion is well closed off. It extends anteriorly almost to the 
postoptic recess. From its caudal surface a slender stalk con- 
nects the hypophysis with the mouth (fig. 6). The ventral 
end of the anterior lobe is somewhat wider than the mid part 
which connects it with the very much wider posterior portion or 
Rathke’s pouch (fig. 21). Distinct furrows on the anterior 
(ventral) side partially separate the lateral anlagen of the inferior 
sacs from the original Rathke’s pouch. A slight ridge on the 
caudal (superior) surface joins the two inferior sacs (fig. 14). 
In a median sagittal section (fig. 6) a shallow groove marks the 
connection between them. This connection is dorsal (caudal) 
to the stalk joining the hypophysis to the mouth. On the lateral 
dorsal surface at the posterior end of Rathke’s pouch two very 
slight outpouchings indicate the position of the developing 
superior lobe (fig. 14). 
