AJP - Endocrinology and Metabolism, Vol 254, Issue 5 E639-E651, Copyright © 1988 by American Physiological Society
Indexes of vitamin D deficiency in Japanese quail embryos
M. A. Elaroussi, L. R. Forte, H. V. Biellier, S. L. Eber, R. E. Poelling and W. J. Krause
Department of Animal Sciences, College of Agriculture, University of Missouri-Columbia.
Effects of vitamin D deficiency (-D) on mineral homeostasis were
investigated in Japanese quail embryos. The -D embryos from 1,25(OH)2D3-fed
hens became progressively calcium deficient, as documented by hypocalcemia
and reduced calcium accumulation by the skeleton, yolk sac, and allantoic
fluid. Plasma phosphate was progressively elevated between days 11 and 15.
Increased calcium accumulation by the skeleton, yolk sac, and allantoic
fluid occurred between days 12 and 15 in +D embryos. Phosphate and
adenosine 3',5'-cyclic monophosphate (cAMP) concentrations of allantoic
fluid increased in +D embryos during the period of shell calcium
mobilization. Further increases in phosphate and cAMP excretion into
allantoic fluid occurred in -D embryos, although no calcium was absorbed
from the shell. Renal 25(OH)D-1-hydroxylase activity increased between days
11 and 13, whereas the adenylate cyclase response to parathyroid hormone
was lost in -D embryos by day 14. These changes in renal function are
indicative of secondary hyperparathyroidism in the -D embryos.
Differentiation of villus cavity and capillary covering cells occurred in
the chorionic epithelium of -D embryos, but eggshell calcium was apparently
not absorbed. In contrast, 75% of the total body calcium of newly hatched
(+D) chicks was obtained from the eggshell. Thus the dissolution and/or
transport of eggshell calcium is dependent on vitamin D in quail embryos.
