. The endocrine organs; an introduction to the study of internal secretion . ntermedia. When sucha separation is effected the term posterior lobe has been given to parsnervosa plus pars intermedia, the pars anterior being termed in contra-distinction anterior lobe. Pars anterior seu glandularis.—As already mentioned, this is formedof trabecular masses of epithelium-like cells between which are verynumerous sinus-like blood capillaries lying in intimate relation to the cells, 78 The Endocrine Organs which are indeed sometimes set closely round the blood-spaces. Soabundant are the blood-vessels
. The endocrine organs; an introduction to the study of internal secretion . ntermedia. When sucha separation is effected the term posterior lobe has been given to parsnervosa plus pars intermedia, the pars anterior being termed in contra-distinction anterior lobe. Pars anterior seu glandularis.—As already mentioned, this is formedof trabecular masses of epithelium-like cells between which are verynumerous sinus-like blood capillaries lying in intimate relation to the cells, 78 The Endocrine Organs which are indeed sometimes set closely round the blood-spaces. Soabundant are the blood-vessels that a photograph of a section of this partof the injected organ appears almost black (fig. 47): the contrast with thepars intermedia and pars nervosa being marked. The pars anterior issupplied with blood by about eighteen to twenty small arterioles whichconverge towards the infundibulum from the circle of Willis and pass intoit along the stalk (Dandy and Goetsch). They open into the sinus-likechannels which in this part take the place of capillaries; the blood from SSB. FIG. 49.—Section of ox pituitary at intraglandular cleft (&), showing on left side (a) a portionof the highly vascular pars anterior, and on right side (c) a portion of pars 200 diameters. these passes away by corresponding venules (fig. 48). The pars anterior ofthe pituitary constitutes one of the most vascular organs in the body. The cells of the pars anterior appear as two varieties, viz., clear, non-staining (chromaphobe), and granular, staining (chromaphil): and thegranular cells are again divisible into oxyphil and basiphil, thosestaining with acid and basic dyes respectively, the oxyphil cells beingnormally by far the more numerous. It has been suggested that thesethree types of cells represent different stages of the same cell; this isprobably only true for the chromaphobe cells and for the cells with oxyphilgranules. The last-named cells are very distinct (figs. 49 and 50,
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