A text-book of physiology, for medical students and physicians . invests the body and neck of therior or nervous lobe. To this latter the special name ofthe pars intermedia has been given. When fully formed theposterior lobe consists of two parts, the pars nervosa, composed ofneuroglia cells and fibers and ependymal cells, and an investing of epithelial cells, derived from the buccal ectoderm and* Klliott and Tuckett, Journal of Physiology, 34, 332, L906. SECRETION OF THE DUCTLESS GLANDS. 845 known as the pars intermedia* (see Fig. 289). The cells of thepars intermedia may also penetrate more
A text-book of physiology, for medical students and physicians . invests the body and neck of therior or nervous lobe. To this latter the special name ofthe pars intermedia has been given. When fully formed theposterior lobe consists of two parts, the pars nervosa, composed ofneuroglia cells and fibers and ependymal cells, and an investing of epithelial cells, derived from the buccal ectoderm and* Klliott and Tuckett, Journal of Physiology, 34, 332, L906. SECRETION OF THE DUCTLESS GLANDS. 845 known as the pars intermedia* (see Fig. 289). The cells of thepars intermedia may also penetrate more or less into the sub-stance of the pars nervosa. Howellf and others have shown thatextracts of the anterior lobe when injected intravenously havelittle or no physiological effect, while extracts of the posteriorlobe, on the contrary, cause a marked rise of blood-pressure andslowing of the heart-beat. These effects resemble in general thoseobtained from adrenal extracts, but differ in some details. Itwas subsequently shown by Schafer and Herring! that extracts. Fig. 289.—Mesial sagittal section through developing pituitary body of a human fetus(fifth month;. Drawing from a photograph.—(Herring.) a, Optic chiasma ; b, tongue-like process of epithelium ; c, third ventricle ; d, anterior lobe ; e, neck of posterior lobe ;/, epithelium surrounding neck ; g, epithelial cleft ; h, posterior lobe. made from the posterior lobe when injected into the blood causea dilatation of the renal vessels and an increased secretion ofurine. Evidence was thus obtained that the posterior lobefurnishes an internal secretion which has a specific effect upon theorgans of circulation and upon the kidneys. Further work byHerring§ has made it very probable that this internal secretion * See Herring, Quarterly Journal of Experimental Physiology, 1, 121,161, 1908. ** t Journal of Experimental Medicine, 3, 245, 1898; also Schafer andVincent, Journal of Physiology, 25, 87, 1899; and Herring, QuarterlyJour
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