Abstract: Objective Single-cell RNA sequencing (scRNA-seq) was used to systematically delineate the cell atlas and molecular tracks of human early erythroid development at the single-cell level. Methods The dataset of scRNA-seq of human embryo yolk sac at CS15 stage was analyzed by principal component analysis (PCA), cluster analysis and pseudostime analysis to observe the expression of marker genes in different cell clusters, and to predict the occurrence time and development path of erythroid. Results In different cell clusters of yolk sac at CS15 stage, marker genes of erythrocytes and progenitor cells were differentially expressed. The occurrence time of various cells was different, and there was some heterogeneity in erythrocytes in the yolk sac. There were abundant types of cells in the yolk sac at CS15 stage, which could include vascular endothelial cells, hematopoietic progenitor cells, granulocytes, different status of red blood cells and monocytes. Conclusions It is speculated that early development path of human erythroid is as follows: vascular endothelial cells differentiate into hematopoietic progenitor cells, further differentiate into red myeloid progenitor cells, and finally produce megakaryocytes and erythrocytes.

Key words: single-cell RNA sequencing, early erythroid development, embryonic phase, yolk sac