Describe the key feature of stem cells and discuss their applications in research and medicine. Please provide examples.

Stem cells are undifferentiated cells with the ability to differentiate to form specialised cells, such as erythrocytes and neurons, or to self-renew in order to repopulate and produce more stem cells. Their ability to either differentiate or self-renew is their key feature. For example, stem cells in the bone marrow can differentiate to produce all types of blood cells, including erythrocytes, neutrophils and lymphocytes in mammals. In plants, stem cells located in the meristem can differentiate to produce cells that will form the xylem and phloem.
Stem cells are currently being researched as treatment strategies for neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases, as well as other types of diseases, as stem cells can differentiate into many different cell types allowing for tissue repair. Furthermore, stem cell research provides insights into developmental biology and the nature of stem cells throughout development and the formation of specialised tissues in the embryo.