Vimentin in Developing Human Adrenal Medulla Cells.

The development of the human adrenal gland involves dramatic structural reorganization, including migration of adrenal medulla cells, changes in cell shape, and complex dynamics of distinct cell populations. These processes require dynamic remodeling of the cytoskeleton. In this study, we investigated vimentin-a key regulator of cell shape changes-in a population of developing adrenal medulla cells, which we call large cells (LCs). We performed double immunofluorescence for tyrosine hydroxylase and vimentin on adrenal glands from human fetuses aged from 8 gestational weeks to 11 days postnatally and compared our findings with recently published single-cell transcriptomics data. We found that the ratio of vimentin-positive LCs did not change significantly with age, and staining intensity was even higher in later fetuses, indicating that vimentin immunoreactivity does not decline with age. In contrast, analysis of the scRNA-seq dataset revealed a decrease in the proportion of vimentin-positive cells within the subpopulation of late chromaffin cells. We attribute these differences to both the high stability of vimentin filaments relative to their short-lived mRNA and the physiological heterogeneity of developing chromaffin cells, the precise causes of which remain to be determined.