Endocrinology, Vol 130, 2651-2659, Copyright © 1992 by Endocrine Society

ARTICLES

L-thyroxine and 3,5,3'-triiodothyronine concentrations in the chicken egg and in the embryo before and after the onset of thyroid function

M Prati, R Calvo, G Morreale and G Morreale de Escobar
Unidad de Endocrinologia Molecular, Universidad Autonoma de Madrid, Spain.

The concentrations of T4 and T3 were measured by specific RIAs in chicken embryonated eggs and embryonic tissues before (at 4 and 6 days of incubation) and after the onset of thyroid function (at 10-20 days). All samples were submitted to extensive delipidation and purification. T4 and T3 were found in the yolk, as described by others, and also in the egg white, although at lower concentrations. The initial total maternal supplies per egg are 67 ng T4 and 30 ng T3 in the yolk, and 2.4 ng T4 and 1.9 ng T3 in the egg albumen. Whole 4-day-old embryos contained a total of 2.48 pg T4 and 0.65 pg T3. The head (mostly brain) of 6-day old embryos contained 4.1 pg T4 and 4.6 pg T3; T4 (but not T3) was also measurable in the carcass. The concentrations of T4 increased progressively between 10 and 20 days in the brain, eyes, liver, and heart; they were especially high in the eyes (4.8 ng/g) and liver (8.2 ng/g) at 20 days. T3 levels increased markedly in the brain (to 5.1 ng/g at 20 days) and less markedly in the eyes (to 1.3 ng/g) and heart (to 1.6 ng/g), but were low and stable in liver up to 18 days (0.3 ng/g), after which there was a sudden increase to 1.4 ng/g at 20 days. Iodothyronines are, therefore, available to the chick embryo throughout development both before and after the onset of thyroid function. T3 concentrations, especially in the brain, reach much higher levels than previously inferred from the low plasma T3 levels. These findings show similarities with those described for the fetal rat.

This article has been cited by other articles:

				A. H. Conrad, J. M. Strafuss, M. D. Wittman, S. Conway, and G. W. Conrad Thyroxine Increases the Rate but Does Not Alter the Pattern of Innervation during Embryonic Chick Corneal Development Invest. Ophthalmol. Vis. Sci., January 1, 2008; 49(1): 139 - 153. [Abstract] [Full Text] [PDF]

				A. H. Conrad, Y. Zhang, A. R. Walker, L. A. Olberding, A. Hanzlick, A. J. Zimmer, R. Morffi, and G. W. Conrad Thyroxine Affects Expression of KSPG-Related Genes, the Carbonic Anhydrase II Gene, and KS Sulfation in the Embryonic Chicken Cornea Invest. Ophthalmol. Vis. Sci., January 1, 2006; 47(1): 120 - 132. [Abstract] [Full Text] [PDF]

				B. Gereben, J. Pachucki, A. Kollar, Z. Liposits, and C. Fekete Ontogenic Redistribution of Type 2 Deiodinase Messenger Ribonucleic Acid in the Brain of Chicken Endocrinology, August 1, 2004; 145(8): 3619 - 3625. [Abstract] [Full Text] [PDF]

				S. D. Johnston, C. B. Daniels, D. Cenzato, J. A. Whitsett, and S. Orgeig The pulmonary surfactant system matures upon pipping in the freshwater turtle Chelydra serpentina J. Exp. Biol., February 1, 2002; 205(3): 415 - 425. [Abstract] [Full Text] [PDF]

				L. C. Sullivan and S. Orgeig Dexamethasone and epinephrine stimulate surfactant secretion in type II cells of embryonic chickens Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2001; 281(3): R770 - R777. [Abstract] [Full Text] [PDF]

				G. Morreale de Escobar, M. Jesús Obregón, and F. Escobar del Rey Is Neuropsychological Development Related to Maternal Hypothyroidism or to Maternal Hypothyroxinemia? J. Clin. Endocrinol. Metab., November 1, 2000; 85(11): 3975 - 3987. [Abstract] [Full Text]

				G. M. Wahlström and B. Vennström Requirements for Repression of Retinoid X Receptor by the Oncoprotein P75gag-v-erbA and the Thyroid Hormone Receptors Mol. Endocrinol., May 1, 1998; 12(5): 645 - 653. [Abstract] [Full Text]

				F. Lezoualc'h, I. Seugnet, A. L. Monnier, J. Ghysdael, J.-P. Behr, and B. A. Demeneix Inhibition of Neurogenic Precursor Proliferation by Antisense [IMAGE] Thyroid Hormone Receptor Oligonucleotides J. Biol. Chem., May 19, 1995; 270(20): 12100 - 12108. [Abstract] [Full Text] [PDF]

				M. Kelley, J. Turner, and T. Reh Ligands of steroid/thyroid receptors induce cone photoreceptors in vertebrate retina Development, January 11, 1995; 121(11): 3777 - 3785. [Abstract] [PDF]