The thyroid and parathyroid glands in the Rhinocerotidae

As a contribution to rhinoceros splanchnology obsevations are submitted upon the gross and microscopical anatomy of the rhinoceros thyroid and parathyroid glands, following a particular examination of these organs in examples of the genera Rhinoceros, Didermocerus, Ceratotherium and Diceros .     

Limited depletion of central adrenaline stores following administration of adrenaline synthesis inhibitors in rats

The aim of the present study was to maximise the selective depletion of adrenaline stores in the rat brainstem and spinal cord, obtained by administering inhibitors of adrenaline synthesis. Partial depletions of adrenaline in the hypothalamus and medulla were observed after a single injection of either LY134046 or SKF 64139 (40 mg/kg i.p.). The rate and extent of depletion seen in the hypothalamus 3 or 6 h after a single dose of LY134046 could be increased by simultaneous exposure to cold or by lowering blood pressure, but not by prior administration of the synthesis inhibitor at 12 h intervals for 3 days. None of the treatments used were able to significantly lower spinal cord adrenaline levels, despite at least 80% inhibition of spinal cord PNMT activity. These results suggest that the ability to reduce central adrenaline stores by synthesis inhibition is limited, especially in the spinal cord.     

Hypoplasia of the bone marrow in rats following removal of the parathyroid glands

Removal of the parathyroid glands caused a marked and permanent lowering of the mitotic activity in rat bone marrow, which was followed by a pronounced decline (ca. 40%) in the size of the marrow's nucleated cell population. These changes occurred only when the hypocalcemia induced by the lack of parathyroid hormone (PTH) was maintained by feeding the animals a calcium deficient diet. Since the overall marrow hypoplasia was almost entirely due to strikingly large reductions (ca. 70%) in the size of the erythroid and lymphoid subpopulations, it is concluded that PTH and calcium are major physiological regulators of the proliferation of erythroid and lymphoid cells.     

The thyroid and parathyroid glands in the Giant panda, Ailuropoda melanoleuca

Observations are submitted upon the anatomy of the thyroid and parathyroid glands of Ailuropoda melanoleuca following gland investigation in three specimens. Variations of thyroid configuration and of parathyroid topography are noted, the thyroid vasculature is described in detail and an initial contribution is made to thyroid and parathyroid histology in this genus.     

High adrenaline sensitivity of the mitochondrial processes in the mucosa of the small intestine in rats

Higher adrenalin sensitivity of mitochondrial processes in the small intestinal mucosa compared to that in liver mitochondria, was revealed under specially devised conditions of work with isolated mitochondria retaining their natural properties. Fifteen minutes after intraperitoneal injection of adrenalin into rats in a dose of 5 micrograms/100 bw an increase in Ca2+ capacity was seen only in intestinal mucosa mitochondria. The adrenalin-induced activation of oxidative phosphorylation was more remarkable in intestinal than in liver mitochondria at the initial stages of adrenalin action. The effect of adrenalin was completely reversed by the beta-blocker propranolol only in liver mitochondria. After 3 hours the adrenalin-induced activation of phosphorylation in the mitochondria ceases, whereas in the small intestinal mucosa it still persists.     

Immunohistochemical demonstration of keratins in the cysts of thyroid glands, parathyroid glands, and C-cell complexes of the dog

Cyst structures were often detected in and around thyroid glands of the dog. The present study revealed the frequency of occurrence, the light microscopic features, and the immunoperoxidase reactions to anti-keratin and anti-19S-thyroglobulin antisera of each cyst located in parathyroid III, parathyroid IV, thymus IV, C-cell complexes, and thyroid parenchyma from 112 dogs. In each location, cysts showed characteristic features. In parathyroid III, the cysts were covered with single or pseudostratified epithelium composed of ciliated cells; whereas in parathyroid IV they were covered with keratinizing stratified squamous epithelium. In C-cell complexes, small cysts lined with small packed cells were predominant, and large cysts lined with single cuboidal cells or stratified squamous cells were also present. In thymus IV located in the close vicinity of parathyroid IV, cyst epithelium consisted of several types of cells showing variable features. In thyroid parenchyma, there were several types of cysts: some were covered with ciliated columnar cells, and others were covered with two or multilayers of small packed cells or cuboidal cells. In spite of these differences in appearance of the cysts located in different tissues, all their epithelia were immunoreactive to the keratin antisera, except for small cysts in C-cell complexes, which were regarded as immature structures. Thus, the presence of keratin filaments in epithelial cells seems to be a characteristic feature of all cysts. The lumens of each cyst contained variable amounts of amorphous materials, which showed colloid-like, flocculent, foamy, and granular features and were periodic acid-Schiff-positive in variable degrees, from weak to intense. Although the lumenal contents of the cysts in parathyroid III revealed no immunoreactivity for 19S-thyroglobulin, those in thyroid parenchyma, C-cell complexes, parathyroid IV, and thymus IV reacted strongly with the 19S-thyroglobulin antiserum.