0
views
0
recommends
+1 Recommend
1 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found

      Changes in Skin Color and Fine Structure of the Intermediate Pituitary Gland of the Frog, Rana nigromaculata, after Extirpation of the Median Eminence

      Read this article at

      ScienceOpenPublisherPubMed
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          The pars intermedia was investigated by electron microscopy, with relation to changes in skin color, in frogs ( Rana nigromaculata) that were first adapted to a white background, then subjected to extirpantion of the median eminence, and subsequently kept on the white background for various periods. It was found that: 1. Following extirpation, the animals begin to darken on a white background and to lose their background adaptability. After 2–3 h, the extirpated animals become intensely dark and remain so for at least 2 weeks. From 3 or 4 weeks on, such animals begin to adapt to their background again and slowly blanch, although they do not lighten at 6 months as fully as do intact animals at the end of that period. 2. The pars intermedia cells at the irreversible, dark stage of the extirpated animals show a progressive decrease in the number of secretory granules in the cytoplasm, followed by an incease in the amount of rough-surfaced endoplasmic reticulum. In the 2-day animals, there is a marked diminution of the secretory granules and a slight expansion of the rough-surfaced endoplasmic cisternae. At this stage, degenerative changes appear in the ordinary nerve endings that make synaptic contact with the pars intermedia cells. 3. The pars intermedia cells at the adaptive, light stage of the extirpated animals indicate the successive accumulation of secretory granules in the cytoplasm, followed by the reduction of rough-surfaced endoplasmic reticulum. The appearance of the cells of the 6-month animals seems very similar to that seen in the preoperative, white-background-adapted animal. At this stage, the degenerated synapses rapidly progress toward normal. These findings were discussed with particular respect to the hypothalamic neural inhibition of the pars intermedia, leading to the conclusion that this inhibition appears to operate first on the release mechanism of melanophore-stimulating hormone (MSH) in the gland through the ordinary, possibly adrenergic, nerve fibers originating in the hypothalamus. Furthermore, it was suggested that the synthesis of MSH is regulated by a feedback mechanism activated by the hormone stored in the gland.

          Related collections

          Author and article information

          Journal
          NEN
          Neuroendocrinology
          10.1159/issn.0028-3835
          Neuroendocrinology
          S. Karger AG
          0028-3835
          1423-0194
          1971
          1971
          19 March 2008
          : 8
          : 3-4
          : 180-197
          Affiliations
          Department of Anatomy, Fukushima Medical College, Fukushima
          Article
          122027 Neuroendocrinology 1971;8:180–197
          10.1159/000122027
          5093954
          © 1971 S. Karger AG, Basel

          Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

          Page count
          Pages: 18
          Categories
          Paper

          Comments

          Comment on this article