THE HYPOPHYSIS IN REPTILES 269 



In very young adult Chrysemys, the cells of the anterior lobe 

 are arranged in cords, three to five cells thick. The staining 

 reactions are much less marked than in older adults. Cells 

 staining homogeneously with eosin, others clear and vacuolated, 

 and a third kind staining darkly with iron haematoxylin occur 

 in the same tubule. The nuclei are oval, the cytoplasmic zone 

 narrow. The nucleolus is distinct and the chromatin network 

 dense. A thin layer of narrow cell strands forms the pars tu- 

 beralis. Here the cytoplasm is light-staining and the nuclei 

 elongated. The laminae of the pars intermedia are four or five 

 layers deep; the cells show no granules and the nuclei stain 

 darker than those of the anterior lobe. 



In 12 mm. Tropidonotus embryos there are about five rows 

 of elongated nuclei in the hypophyseal wall. The surface of 

 Rathke's pouch is regular, while many epithelial buds project 

 from the surface of the anterior lobe. The basal membrane is 

 indistinct. The nuclei of the distal ends of the lateral buds are 

 spherical while those of Rathke's pouch and those lining the 

 lumen of the anterior lobe are elongate. The entire anterior 

 lobe of a 10.5 mm. Eutaenia is a mass of glandular cords and 

 tubules. Many thickened regions in the wall of the ventral 

 part of Rathke's pouch and the occasional extensions of the 

 lumen into them indicates beginning glandular development from 

 this part. 



In a 10 cm. (total length) Tropidonotus the pars intermedia 

 is a thick-walled, flattened vescicle (fig. 38) from which only 

 very few glands are, as yet, outlined. In the inner layer of cells 

 surrounding the lumen, the nuclei are oval, while in the outer 

 three or four layers the nuclei are less crowded and are spherical. 

 The glandular buds of the anterior lobe are long, sometimes 

 dilated at the ends, where there may be a small lumen or cyto- 

 plasmic zone. The lumina are surrounded by a two layered 

 epithelium containing round nuclei. One can hardly character- 

 ize the cells of the hypophysis in embryo alligators as lymphoid 

 tissue, although Reese so regards them. Bruni has stated that a 

 differentiation in staining reaction of the cells is present in a 44.7 

 mm. Gongylus embryo where the hypophysis is composed of 



