BACKGROUND:Astrocytes are the most abundant cells in the central nervous system,and various subsets of astrocytes are heterogeneous,performing a variety of special functions.Single-cell RNA sequencing(scRNA-seq)technology developed in recent years has extended our understanding of astrocyte heterogeneity from the perspective of transcriptome profiling. OBJECTIVE:To summarize the heterogeneity of scRNA-seq technology in different time and space,and pathological states and expand our knowledge of astrocyte heterogeneity on both molecular and functional levels. METHODS:The relevant articles on astrocyte heterogeneity and scRNA-seq were searched on PubMed,Elsevier,and CNKI databases.The search terms were"astrocytes,scRNA-seq,heterogeneity,Alzheimer disease,spinal cord injury,multiple sclerosis"in Chinese and English.Finally,74 articles were selected for viewing after screening according to inclusion criteria. RESULTS AND CONCLUSION:scRNA-seq studies related to the heterogeneity of astrocytes have shown that astrocyte is significantly heterogeneous across four aspects:species,developmental stage,central nervous system region,and pathological state.(1)Unique expression of certain genes occurs in astrocytes of different species,and the discovery of species-specific genes is beneficial for the translation of clinical studies.(2)During astrocyte development,differential gene expression emerged in the cellular subtypes identified at each stage,which further refined the cellular lineage of astrocytes and laid the foundation for the study of astrocyte developmental trajectories and mechanisms.(3)The discovery of differential gene expression allows regional localization of different astrocyte subpopulations and assists in the diagnosis and treatment of neurological diseases.(4)Astrocyte heterogeneity revealed by scRNA-seq can provide specific markers at the time of disease diagnosis and identify potential therapeutic targets.(5)The heterogeneity of astrocytes exists in many aspects,interacts with each other and is complex.The mechanisms of its generation,maintenance and transformation remain unclear.At present,molecular research on the single-cell level is still lacking.Linking transcriptionally defined astrocyte subpopulations to cellular activity,behavior and disease markers in real time remains one of the great challenges in the field.

Objective To investigate the mouse liver blood vessel images using phase contrast X-ray imaging with synchrotron radiation. Methods 6 female C57BL/6 mice were randomly divided into two groups, 3 mice in each group. In one group, livers excised after hgated arteries, veins and common bile duct. In another group, iodine infused via the portal vein and drained from inferior vena cave until all the blood in the portal veins and hepatic veins was displaced. After infusion, arteries, veins and common bile duct were ligated and livers were excised. Results Blood vessel images were clearly produced by diffraction enhanced imaging. This method can discriminate vessels down to about 40 μm in diameter without contrast agent. Using a contrasting agent more details could be produced. In one liver lobe, the entire branch of the portal vein could be clearly produced by one by one phase contrast image from the main axial blood vessels of liver lobe to the nine generation of branching. Conclusions Phase contrast imaging has the advantage of good contrast and high spatial resolution. [Key wnrds] Synchrotron radiation; Phase contrast imaging; Diffraction enhanced imaging; Blood vessel; X-rays