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Retinoic acid (simplified nomenclature for all-trans-retinoic acid) is a metabolite of vitamin A 1 (all-trans-retinol) that is required for embryonic development, male fertility, regulation of bone growth and immune function. [2] All-trans-retinoic acid is required for chordate animal development, which includes all higher animals from fish to ...
Group A had 90 fetuses of 9–12 weeks of gestation and the weight varied between 1-14 grams. Group B had 337 fetuses, age 13–16 weeks of gestation with weight variation between 15 and 105 grams whereas the third group had 435 fetuses of 17–20 weeks of gestation with a weight range between 106 and 310 grams.
During development, retinoic acid, a metabolite of vitamin A, is used to stimulate the growth of the posterior end of the organism. [12] Retinoic acid binds to retinoic acid receptors that acts as transcription factors to regulate the expression of Hox genes. Exposure of embryos to exogenous retinoids especially in the first trimester results ...
As for the risks of too much RA during embryogenesis, the prescription drugs tretinoin (all-trans-retinoic acid) and isotretinoin (13-cis-retinoic acid), used orally or topically for acne treatment, are labeled with boxed warnings for pregnant women or women who may become pregnant, as they are known human teratogens. [31] [32]
CRBP I/II, cellular-binding proteins involved in transport of retinol and metabolites into retinyl esters for storage or into retinoic acid. [14] CRABPs, cellular retinoic acid–binding proteins capable of binding retinol and retinoic acid with high affinity. [15] [16] [17] It has also been characterized that CRABPs are involved in many ...
The 3 ′ (3 prime end) genes in the Hox cluster are induced by retinoic acid in the hindbrain, whereas the 5 ′ (5 prime end) Hox genes are not induced by retinoic acid and are expressed more posteriorly in the spinal cord. Hoxb-1 is expressed in rhombomere 4 and gives rise to the facial nerve.
Retinoic acid via the retinoic acid receptor influences the process of cell differentiation and, hence, the growth and development of embryos. During development, there is a concentration gradient of retinoic acid along the anterior-posterior (head-tail) axis. Cells in the embryo respond to retinoic acid differently depending on the amount present.
The yolk sac is a membranous sac attached to the embryo, which provides nutrients and functions as the circulatory system of the very early embryo. [ 1 ] The lateral body wall folds, pulling the amnion in with it so that the amnion surrounds the embryo and extends over the connecting stalk, which becomes the umbilical cord , which connects the ...