DEVELOPMENT OF THE HYPOPHYSIS 429 
rior lobe stains readily, and indeed, sometimes more deeply than 
that of the anterior lobe. The nuclei, on the other hand stain 
less deeply than those of the anterior lobe. Those of the inferior 
lobe frequently stain very lightly. Sterzi has stated that the 
cytoplasm of the superior lobe stains with difficulty. 
d. Connective tissues, blood vessels and nerves. In very small 
embryos there are only occasional connective tissue cells lying 
between the hypophysis and the brain and vascular sac above, 
and these cells are along the dorso-lateral walls. Beginning in 
33 mm. embryos, however, there is a thin layer of mesenchyma 
between the dorsal (posterior) end of the hypophysis and the 
anlage of the vascular sac. In 50 mm. embryos small blood 
vessels are found between the superior lobe and the saccus 
vasculosus (fig. 37). At this time, also, a thin layer of mesen- 
chyma separates the hypophysis from the brain floor. In the 
superior lobe of the adult occasional small strands of connective 
tissue are found in the center of the core of nuclei of the 
columns. 
They anastomose with the connective tissue between the 
columns but have no cytoplasmic zone bordering them as do the 
larger, more vascular connective tissue strands between the 
columns. 
In the pup, there are small capillaries in the connective tissue 
over the anterior lobe of the hypophysis. On the ventral side there 
is considerable connective tissue between the developing tubules. 
The few capillaries here are not large. The capillaries between 
the columns of the dorsal lobe are large and numerous. These 
capillaries or sinusoids are to be found in the interstices between 
the cell columns and also between the ends of the columns and 
the overlying vascular sac. In the adult the capillaries over the 
anterior lobe are somewhat larger. There has been some in- 
crease in the size and number of the capillaries between the tub- 
ules of the anterior lobe and the same is true in the superior lobe 
between the cell columns. 
Nerves have been described in the nae by Edinger 
(92), Sterzi (09) and others. Sterzi described the floor of the 
brain in the hypophyseal area (above the superior lobe of the hy- 
