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Calcium mobilization, water balance, and growth in embryos of the agamid lizard Amphibolurus barbatus

journal contribution
posted on 2023-05-20, 00:52 authored by Packard, MJ, Packard, GC, Miller, JD, Menna JonesMenna Jones, Gutzke, WHN
Embryos of the agamid lizard Amphibolurus barbatus are at developmental stage 29 of Dufaure and Hubert at the time of oviposition. Mobilization of calcium and other nutrients from the yolk proceeds slowly for the first half of incubation, during which time embryonic growth also proceeds slowly. During the second half of incubation, however, embryos withdraw calcium and other nutrients from the yolk very rapidly, and growth rates are correspondingly high. Approximately 60% of the calcium used by developing embryos is obtained from the yolk, but fully 40% of their requirement is met by calcium mobilized from the eggshell. Very little calcium remains in residual yolk of hatchlings, so this yolk must be used in maintenance metabolism rather than in growth of neonates. No dichotomy exists among oviparous, amniotic vertebrates with respect to sources of calcium used by developing embryos, but one does exist with respect to patterns of mobilization of this element. Whereas calcium is extracted from yolk of embryonic reptiles throughout incubation, it actually is deposited in yolk of embryonic birds after the midpoint in development.

History

Publication title

Journal of Experimental Zoology

Volume

235

Pagination

349-357

ISSN

0022-104X

Department/School

School of Natural Sciences

Publisher

Wiley-Liss

Place of publication

Div John Wiley & Sons Inc, 605 Third Ave, New York, USA, Ny, 10158-0012

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the biological sciences

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