THE DIENCEPHALIC FLOOR Zat 
ular evagination shows a constriction at its point of junction 
with the infundibular region, in this way demarcating the 
definitive infundibular stem (1/1) and the infundibular process 
(13). The ventricular cavity extends through the narrow in- 
Ss 
SS 
iy 
SENS 
os 
SESS 
SOO 
3 
Fig. 9 Mesial view of forebrain reconstruction of 10mm. catembryo. X 100. 
The unshaded area shows the cut surfaces of the reconstruction. 11, infundib- 
ular stem; 12, infundibular canai; 13, infundibular process; 17, infundibular 
region; 19, inter-optic groove; 20, lamina terminalis; 24, mid-brain; 25, mam- 
millary region; 29, optic evagination; 34, post-infundibular eminence; 35, post- 
infundibular recess; 37, post-mammillary evagination; 39, paraphysis; 40, 
recess of the infundibular process; 43, thalamencephalon; 44, telencephalon; 
4§, tuberculum postero-superius; 46, tubercle of the floor of Schulte. 
fundibular process, thus giving rise to the infundibular canal 
(12) and the infundibular recess (40). Dorsal to the infundibular 
stem the floor of the ventricle shows a large post-infundibular 
evagination, which from this time maintains the same general 
