OR04-1 The Developmental Origin and the Specification of the Adrenal Cortex in Humans and Cynomolgus Monkeys

Abstract

Abstract The adrenal cortex and gonads are the two major endocrine hubs that participate in the hormonal regulation of vital aspects of mammalian homeostasis. Accordingly, their developmental aberrancies drive various congenital and adult-onset diseases. Lineage tracing studies in mice reveal that the adrenal cortex and gonads originate from a common progenitor, the adrenogonadal primordium. However, the specification pathways of the adrenal cortex and gonads and their lineage relationship remain poorly understood in humans. Here, we conduct the high resolution spatial and temporal lineage trajectory mapping of early human adrenal and gonadal lineages using single cell transcriptomics and histologic profiling on human embryos at 3-8 week post fertilization. We find that in humans, the adrenocortical lineage originates in a temporally and spatially distinct fashion from the gonadal lineage, arising earlier and more anteriorly within the coelomic epithelium. The adrenal primordium arises from adrenogenic coelomic epithelium via an epithelial-to-mesenchymal-like transition, which then progresses into the steroidogenic fetal zone via both direct and indirect routes. Notably, we find that adrenocortical and gonadal lineages exhibit distinct HOX codes, suggesting distinct anterior-posterior regionalization. Together, our assessment of the early divergence of these lineages challenges the paradigm established in rodents and present evidence that the specification programs directing the formation of adrenal glands and gonads differ between rodents and humans. The molecular details of early lineage diversification of human adrenals and gonads will serve as both a framework for understanding the molecular pathology of human disorders. Presentation: Saturday, June 11, 2022 11:30 a.m. - 11:45 a.m.