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KMID : 0378019740170081045
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New Medical Journal
1974 Volume.17 No. 8 p.1045 ~ p.1058
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The Effect of Total Hypophysectomy on the Adrenal Gland in the Dog
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Abstract
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The purpose of this study is to present the histological effects on the adrenal gland following a new method of total hypophysectomy in the dog. In this study nineteen adult mongrel dogs, weighing from 7 to 10 kg, were used. Eleven of them were male and eight were female.
A newly devised operative method is as follows: Under pentobarbital sodium, 30 mg/kg body weight, intravenous anesthesia the dog was _ placed on the operating table in prone position, and a tube, about 5 cm in diameter, was inserted in the ´mouth to displace the mandibular angle anterodo￢wnwardly. A vertical incision from the midline to just behind the mandibular angle was made on the right side and the temporal muscles were also incised vertically, and retracted these to expose the temporal bone. Following wide craniectomy down to the base of the middle cranial fossa and dural incision, temporal lobe was elevated at the tip of the middle cranial fossa with narrow brain retractor. Since this approach was deep and narrow, a brilliant illumination was thrown from head lamp at the center of binocular magnifier. As the third cranial nerve and internal carotid artery were exposed, arachnoid membrane was torn and aspirated cerebrospinal fluid slowly to obtain wider exposure, then elevated posterior communicating artery to expose the pituitary body and stalk. The stalk was clipped or crushed with microforceps and sectioned with microscissors, then pituitary body was isolated with microelevator and removed in a piece. The wound was closed in layers.
Among these experimental aniamls, 6 dogs were observed for the period of 43-77 days, and in 6 dogs dexamethasone was given intramuscularly for one or two weeks, the rest 7 were not al control group.
Following clinical observation, these animals were sacrificed with intracarotid arterial infusion of 10% neutral formalin solution and removed the brain and adrenal gland, and fixed. iii 10% neutral￢formalin solution. Theremoved brain was examined and the adrenal gland was stained with hematoxylin-eosin, periodic acid Schiff (PAS) and Toluidine blue staining methods.
The observed results were as follows:
1. Adrenal cortical thickness in normal control dogs measured 1.03 mm, which decreased to 0.58 mm (56.3% of control group) following hypophysectomy. With administration of dexamethasone for 1 to 2 weeks, cortical width measured 0.85 mm and .0.56 mm, respectively.
2. The decrease of cortical thickness in hypophysectomized dogs? was interpreted as a consequence of atrophy, being much profound in the zonae fasciculata and reticularis. Proportional thickness of both zonae fasciculata and reticularis was 83.6% in normal control group, but decreased to 73.8% follo￢wing hypophysectomy. With administration of dexamethasone, figures of 75.1% and 64.1% reflected similar reduction as in overall cortical thickness.
3. Those cortical alterations proved to be the results of cytolysis, atrophy and fat depletion of cortical cells, being more prevalent in the zona reticularis. Modification of histological changes following dexamethasone administration was only slight increase of width in zona fasciculata, but reticular zone underwent progressive reduction.
4. Atrophic changes in zona glomerulosa was not remarkable but appeared in relative increase. Effect of administration of dexamethasone accentuated slightly the width of the zona glomerulosa.
5. No significant alterations were found in medullary tissue regardless the type of procedures.
6. Mast cells, distributed normally in the capsule and periadrenal adipose tissue, zona fasciculata and medulla in order, disappeared from the all layers following hypophysectomy, but restored by administration of dexamethasone especially in zona reticularis.
The above experimental features indicated that adrenal cortical atrophy following hypophysectomy was the cytologic reflection of cytolysis, atrophy and fat depletion in zonae fasciculata and reticulasis.´ Administration of dexamethasone disclosed a tendency of suppression of cortical atrophy in the early phase, but the cortex eventually undergwent atrophy as well as similar features in mast cells.
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