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Effects of growth hormone and thyroxine on the occurrence and calcifiability of matrix vesicles in...

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Effects of growth hormone and thyroxine on the occurrence and calcifiability of matrix vesicles in calcifying cartilage of tibae of immature, hypophysectomized rats

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Title	Effects of growth hormone and thyroxine on the occurrence and calcifiability of matrix vesicles in calcifying cartilage of tibae of immature, hypophysectomized rats
Author	Coleman, Stanley Irvin, Jr.
Date	1980
Affiliation/College	College of Graduate Studies
Department	Anatomy
Extent	x, 113 leaves : ill.; 28 cm
Subject.MeSH	Growth Hormone Thyroxine Calcification, Physiologic Hypophysectomy Academic Dissertations
Collection	MUSC Dissertations and Theses
Contributing Institution	Waring Historical Library (MUSC)
Rights	Copyright is held by the author.
Language	English
Type	Text
Format	application/pdf
Media Type	Manuscripts
Resource Identifier	mtd1980_coleman_sr
Abstract	Groups of female Long-Evans rats were hypophysectomized or hypophysectomized plus thyroparathyroidectomized, held for 14 days, then injected with saline, growth hormone or L-thyroxine for two or four days. At the termination of the experiment the proximal ends of the tibiae were analyzed using light and electron microscopy. These saline and hormone injected animals were compared to uninjected, hypophysectomized and control animals. The results of this study indicated that crystal deposition in matrix vesicles is under hormonal influence, either direct or indirect. There was more than a 50% reduction in the number of matrix vesicles containing crystalline material in hypophysectomized animals as compared to controls. Hypophysectomy resulted in a significant decrease, but not the total disappearance of crystal from matrix vesicles. Serum calcium, however, remained normal in hypophysectomized animals. The injection of growth hormone into hypophysectomized animals resulted in approximately 10% more matrix vesicles containing crystal than the controls. L-thyroxine injections into hypophysectomized animals resulted in the number of matrix vesicles with crystal being 5% less than the control values. This was directly correlated with epiphyseal growth plate width. Growth plate thickness was measured using four histochemical techniques: (1) Silver Nitrate, (2) Sudan Black B, (3) Hematoxylin and Eosin, and (4) Alizarin Red S. Each of the techniques exhibited slightly different staining patterns. The classical stain used for growth plate assay (silver nitrate) does not stain the uncalcified growth plate cartilage, whereas sudan black B, believed to stain lipids, stains the longitudinal septae in the hypertrophic zone. Matrix vesicles, which contain lipids and are found in the area described above, may stain with sudan black B. Hematoxylin and eosin stained the cartilagenous growth plate and the areas of initial calcification, resulting in a non-specific staining pattern in regard to mineralized areas. Alizarin red S stained calcified areas a dark red, but left the boundaries between calcified and uncalcified growth plate difficult to precisely measure due to gradual color changes from calcified to uncalcified zones. Amorphous densities were found on the plasma membrane of unstained chondrocytes in the proliferative zone of the growth plate of control, but not hypophysectomized animals. These densities may be direct precursors (intermediates) in the crystalline mineral found in the hypertrophic zone. Growth hormone replacement induced the reappearance of these amorphous densities.

Effects of growth hormone and thyroxine on the occurrence and calcifiability of matrix vesicles in calcifying cartilage of tibae of immature, hypophysectomized rats

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