Vitamin D deficiency in the chick embryo: Effects on prehatching motility and on the growth and differentiation of bones,muscles, and parathyroid glands |
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Authors: | Dr R Narbaitz C P W Tsang |
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Affiliation: | (1) Animal Research Centre, Agriculture Canada, Ottawa, Canada;(2) Department of Anatomy, University of Ottawa, 451 Smythe Rd., K1H 8M5 Ottawa, Ontario, Canada |
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Abstract: | Summary Vitamin D-deficient chicken embryos were obtained by feeding laying hens diets in which 3–7 μg calcitriol replaced the vitamin
D3 supplement. A large proportion of the D-deficient embryos failed to complete the prehatching positional changes required
to start pulmonary respiration. For this reason most of them became cyanotic and had subcutaneous edema and hemorrhages in
the head and neck and died without hatching. Total as well as leg-bone and muscle weights were significantly lower in the
deficient embryos than in the controls and these changes probably explain the inability of the embryos to complete the movements
required to place the beak in contact with the air chamber and start pulmonary respiration. The histological study of the
tibiae showed decreased mineralization with narrower trabeculae and enlarged osteoid seams; bone resorption at the inner surface
was also significantly decreased. The ultrastructural study of parathyroid glands showed increased functional activity reflected
by increased number and size of cisternae of rough endoplasmic reticulum. Injection of 10 ng calcitriol, 1 μg 24, 25-(OH)2D3, or 2 μg 25OHD3 to deficient embryos on the 14th day of incubation improved hatchability, bone and muscle weights, and both bone mineralization
and resorption. |
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Keywords: | Vitamin D deficiency Chick embryo Calcitriol 24 25(OH)2D3 25OHD3 |
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