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. Author manuscript; available in PMC: 2024 Jan 4.
Published in final edited form as: ALTEX. 2022 Jun 23;40(2):217–236. doi: 10.14573/altex.2202231

Fig. 1: Diagram of retinoid pathway in human pregnancy.

Fig. 1:

In development, dietary Vitamin A (retinol) is transferred to the fetus through the placenta into the bloodstream. Dehydrogenase enzymes (RDH and RALDH) transform retinol to retinal and then to the active molecule ATRA. Transport proteins such as STRA6, CRBP, and CRABP move retinol and its forms (retinal, ATRA) from the bloodstream into the nucleus where ATRA binds the retinoic acid receptor / retinoid X receptor complex to initiate gene transcription.