Pi. ch. 
Vent. lat, 
37 
Fig. 33. Through the more rostral portion of the tuberculum olfactorium. 
This is comparable with the level shown of brain H 173, figure 29. The islands 
of Calleja appear as denser cell groups in the marginal velum of the ventral 
region. 
Fig. 34 This section is slightly caudal to the previous one and illustrates the 
deepening of the embryonic fissura hippocampi. 
Fig.35 Through the septum ependymale. The marginal velum is just 
visible. 
Fig.36 Through the foramen interventriculare and the lateral choroid 
plexuses. 
Fig. 37 Through the thalamus and the telencephalon caudal to the di-telen- 
cephalic groove. The roof of the third ventricle is non plexiform. The epen- 
dymal walls of both the lateral plexus and the diencephalic roof plate appear very 
thick. The tissue adjoining the taenia of the lateral plexus, both dorsal and 
ventral to it, is the hippocampus. The same type of cellular arrangement as 
that shown in the depth of the embryonic fissura hippocampi in more rostral 
levels is seen. 
144 
