THE HYPOPHYSIS IN REPTILES 257 



Presumably it is the minute secretory granules which stain thus 

 intensely. The nuclei, although sometimes indented, are more 

 nearly spherical than those of the pars intermedia. The chro- 

 matin network is very light and at least one darkly-staining 

 nucleolus is always present. Often the nuclei of those cells in 

 which the cytoplasm has retained the haematoxylin, particu- 

 larly phosphotungstic haematoxylin, appear as clear spaces, ex- 

 cept for the dark nucleolus. In the clear cells the nuclei may 

 stain very lightly. A few stain intensely with Mallory's phos- 

 photungstic or with iron haematoxylin. Occasional dilated tu- 

 bules 1 with walls of a flattened epithelium and containing degen- 

 erated cells are found. These tubules may be 100 micra long 

 and 50 micra in diameter. Their lumina also contain a colloid- 

 like substance. 



A description of the pars tuberalis includes the thin cortical 

 zone of the anterior lobe, both because of its development and 

 because of its histologic appearance. They are composed of 

 narrow strands of cells which are seldom tubular in arrange- 

 ment, although they may occasionally form solid cords. The 

 strands and cords of the cortical layer are closely applied to 

 those of the anterior lobe, and occasionally extend a short dis- 

 tance into the latter. In many cases they appear to be con- 

 tinuous with those of the anterior lobe. A large amount of 

 connective tissue surrounds the pars tuberalis. The cells are 

 small polyhedrals and stain, like those of the pars intermedia, 

 a light pink (fig. 52). The small nuclei are round and contain 

 a distinct nucleolus. In the cortical zone, as in the main part 

 of the anterior lobe, some nuclei stain very deeply, while only 

 the nucleolus stains in others. In staining reaction the cells 

 of the pars tuberalis and cortical zone appear more like the cells 

 of the pars intermedia than like those of the anterior lobe. 



Lizards 



In adult Sceloporus, there is, as already noted, a central 

 residual lumen in the pars intermedia. The roof of the lumen 

 is composed of a lamina two or three cells deep. A wide periph- 



JOURNAL OF MORPHOLOGY, VOL. 28, NO. 1 



