. A text-book of physiology : for medical students and physicians . bers and ependymal cells, and aninvesting layer of epithelial cells, derived from the buccal ectodermand known as the pars intermedia (see Fig. 299). * Crowe and Wislocki, Johns Hopkins Hospital Bulletin, October, 1914. t For details and references to literature on this and other points in inter-nal secretion consult the excellent wOrk by Biedl, Innere Sekretion, Berlin,1913. SECRETION OF THE DUCTLESS GLANDS. 881 In the pars nervosa characteristic hyaline or colloid bodiesoccur and histological work makes it probable that this
. A text-book of physiology : for medical students and physicians . bers and ependymal cells, and aninvesting layer of epithelial cells, derived from the buccal ectodermand known as the pars intermedia (see Fig. 299). * Crowe and Wislocki, Johns Hopkins Hospital Bulletin, October, 1914. t For details and references to literature on this and other points in inter-nal secretion consult the excellent wOrk by Biedl, Innere Sekretion, Berlin,1913. SECRETION OF THE DUCTLESS GLANDS. 881 In the pars nervosa characteristic hyaline or colloid bodiesoccur and histological work makes it probable that this materialconstitutes an internal secretion. According to Herring,* it isformed from the epithelium of the pars intermedia. The cells ofthe latter invade the pars nervosa, undergo a hyaline degeneration,and are finally discharged into the cerebrospinal liquid of the thirdventricle. Investigations upon the physiology of the pituitarygland have taken the two usual directions, namely, a study of theeffects of removal and a study of the effects of extracts, and obser-. Fig. 299.—Median sagittal section through pituitary of monkey; semidiagrammatic(Herring): a, Optic chiasma; b, third ventricle; c, g, pars intermedia; d, epithelium of parsintermedia extending round neck of pars nervosa; e, pars glandularis seu epithelialis; /, intra-glandular cleft, lying between pars glandularis (e) and pars intermedia (g); h, pars nervosa. vations of this character have been made upon this gland as awhole and upon the anterior and posterior lobes taken of the Posterior Lobe.—Extracts of this lobe contain ma-terial from both the pars nervosa and the pars intermedia, but onthe evidence stated above it may be assumed that the results ob-tained are attributable in reality to the pars intermedia, which hasa glandular structure and is responsible for the hyaline materialfound in the nervous part. When extracts of the posterior lobeare injected into the circulation several distinct
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