The Role of Hormones in the Regulation of Bone Turnover and Eggshell Calcification

Dacke, C. G.; Sugiyama, Toshie

doi:10.1016/b978-0-12-407160-5.00025-7

Cited by 22 publications

(29 citation statements)

References 210 publications

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“…In birds, classical Ca 2+ -regulating hormones include PTH, CT, and 1,25-dihydroxy vitamin D 3 ( Dacke, 1979 ). Parathyroid hormone is secreted by parathyroid glands in response to decreased plasma Ca 2+ level ( Dacke, 2015 ). Calcitonin blocks osteoclastic resorption of medullary bone when an egg is in the magnum of the oviduct, while PTH stimulates osteoclastic bone resorption for eggshell formation during the period when an egg is in the shell gland.…”

Section: Discussionmentioning

confidence: 99%

Improvement of eggshell quality by dietary N-carbamylglutamate supplementation in laying chickens

Yao

Zhou

et al. 2020

Poultry Science

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Egg quality defects seriously reduce the quality grade and increase egg breakage in egg marketing activities. In this study, the effect of N-carbamylglutamate ( NCG ) on eggshell quality was investigated by evaluating calcium absorption and calcification in laying hens. A total of 30 newly hatched female Hy-Line chicks were randomly assigned to the control group (basal diet) and treatment group (basal diet supplemented with 1% NCG). At 25 wk, eggs from each group were obtained to assess egg quality parameters. Blood samples were collected for analysis of mineral, hormone, and amino acids levels at 16 h after laying egg. Uterine tissues were removed and fixed in 4% neutral paraformaldehyde solution or kept in liquid nitrogen for mineral determination, quantitative PCR, and Western blot. Results showed that the egg quality (eggshell thickness, strength and percentage, egg specific gravity, and eggshell effective thickness) was significantly increased while effective thickness of mastoid layer, width of mastoid gap, and mammillary knobs were significantly decreased by dietary NCG supplementation ( P < 0.05). The levels of minerals (Ca, P, Fe, Mg, Na, K) in eggshell, plasma, and uterus were remarkably elevated ( P < 0.05). Meanwhile, the concentrations of calcium metabolism–related hormones (17β-estradiol, parathyroid hormone, and calcitonin) were increased in the NCG group ( P < 0.05). Moreover, expression of calbindin 1, carbonic anhydrase 2, ovalbumin, ovotransferrin, ovocleidin-17, ovocleidin-116, and clusterin mRNAs, as well as calbindin 1 and ATP2A1 proteins in uterus, duodenum, and kidney, was all upregulated in hens fed with NCG ( P < 0.05). In addition, the number of blood vessels in the uterus, height of uterine mucosal folds, villus length in endometrium, and areas of uterine mucosal folds were significantly increased in the NCG group ( P < 0.05). In conclusion, dietary 1% NCG supplementation during 0 to 25 wk can improve eggshell quality through changes in endometrial morphology, expression of calcium metabolism–related genes, and secretion of related hormones to promote eggshell formation in the laying hens.

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Section: Discussionmentioning

confidence: 99%

Improvement of eggshell quality by dietary N-carbamylglutamate supplementation in laying chickens

Yao

Zhou

et al. 2020

Poultry Science

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“…Egglaying birds develop medullary bone within the endosteal cavities of long bones of females only during the reproductive season. This reproductive bone tissue acts as a highly labile Ca store for a short period of time, providing the large quantities of Ca required for mineralization of the calcium carbonate eggshell (see reviews by Simkiss, ; Dacke, ; Dacke et al ., ; Sugiyama & Kusuhara, ; Dacke, Sugiyama & Gay, ). Recently, we showed that medullary bone was also present in a theropod dinosaur as well as ratites, their closest living relatives (Schweitzer et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Alligator osteoderms as a source of labile calcium for eggshell formation

et al. 2015

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The calcium (Ca) demand on alligators in active reproduction is significant, yet the source of this additional Ca is unclear. Three possible sources for Ca mobilization are endolymphatic deposits, as in anurans and some lizards; short-lived skeletal medullary bone or analogous deposits, as in birds; or some other source such as the osteoderm layer of the integument or simply mobilization of structural bone.Here, we investigate possible extra-skeletal sources for labile Ca in the reproducing alligator, including endolymphatic Ca deposits, by analogy with anuran amphibian and some reptiles and integumentary osteodermal (scale) Ca deposits. We conducted X-ray image analyses of skulls for the presence of significant endolymphatic Ca deposits. We also examined dermal bone of scutes (osteoderm, scales) from the dorsal integument using both X-ray and histological analyses. Tissues from reproducing females containing mature but unovulated follicles were compared with those from specimens that had nested (laid eggs) or contained eggs within the oviduct at advanced stages of calcification. A small number of immature specimens and an adult male were also compared. No clear differences were observed in endolymphatic deposits between pre-and post-ovulatory specimens. Scute (osteoderm) X-ray density was significantly greater in females with ripe ovarian follicles compared with those that had recently laid (nested) or contained heavily calcified eggs within their oviducts. The latter groups also showed histological evidence of scute resorption compared with the former, suggesting that the scutes play a role in Ca storage during egglay.

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“…These hormones stimulate osteoblasts within the endosteum to produce new bone that extends into and in some cases fills the medullary cavity of laying birds 8 . MB provides little structural support (but see 7 9 ), rather its primary function is to serve as an easily mobilized source of calcium for eggshell mineralization 7 10 11 12 . MB is gender-specific and does not occur naturally in males or juveniles, only in mature females; however, it can be induced in male birds with the administration of excess estrogen 13 14 .…”

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Chemistry supports the identification of gender-specific reproductive tissue in Tyrannosaurus rex

Schweitzer

Zheng

Zanno

et al. 2016

Sci Rep

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474

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Medullary bone (MB), an estrogen-dependent reproductive tissue present in extant gravid birds, is texturally, histologically and compositionally distinct from other bone types. Phylogenetic proximity led to the proposal that MB would be present in non-avian dinosaurs, and recent studies have used microscopic, morphological, and regional homologies to identify this reproductive tissue in both theropod and ornithischian dinosaurs. Here, we capitalize on the unique chemical and histological fingerprint of MB in birds to characterize, at the molecular level, MB in the non-avian theropod Tyrannosaurus rex (MOR 1125), and show that the retention of original molecular components in fossils allows deeper physiological and evolutionary questions to be addressed.

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The Role of Hormones in the Regulation of Bone Turnover and Eggshell Calcification

Cited by 22 publications

References 210 publications

Improvement of eggshell quality by dietary N-carbamylglutamate supplementation in laying chickens

Improvement of eggshell quality by dietary N-carbamylglutamate supplementation in laying chickens

Alligator osteoderms as a source of labile calcium for eggshell formation

Chemistry supports the identification of gender-specific reproductive tissue in Tyrannosaurus rex

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