In skeletal muscle, progenitors that give rise to myoblasts arise from the paraxial mesoderm. Myoblasts terminally differentiate into muscle cells, which fuse to give rise to myotubes. The myotubes can produce fast-twitch or slow-twitch muscle fibres. Muscle progenitors also give rise to satellite cells, which serve as adult stem cells of the muscle. b | In the blood, self-renewing haematopoietic stem cells (HSCs) give rise to multipotent progenitors (MPPs), which further differentiate into the progenitors of lymphoid lineage (common lymphoid progenitor (CLP)) or myeloid lineage (common myeloid progenitor (CMP)). CLPs differentiate into progenitors of B cells (BCPs) and the progenitors of T cells and natural killer cells (TNKs). CMPs give rise to megakaryocyte–erythroid progenitors (MEPs; which differentiate into erythrocytes and platelets) and the granulocyte–macrophage progenitors (GMPs; which differentiate into monocytes, neutrophils and eosinophils). c | The epidermis is a stratified epithelium composed of progenitor cells in the innermost basal layer and successive layers of differentiating cells as one moves to the surface. The hair follicle develops when primitive epidermal cells form placodes that differentiate into hair follicle stem cells, which in turn undergo further sequential differentiation to produce the outer root sheath (ORS) progenitor cells, the matrix cells, the inner root sheath (IRS) cells, and finally the mature hair follicle. Epithelial stem cells at the junction of the epidermis and hair follicle give rise to the sebaceous gland. d | Neural — neuroepithelial cells expand and produce early neurons, as well as radial glial cells (RGCs). For most of embryogenesis, RGCs divide asymmetrically producing a neuron and a new RGC. During the end of embryogenesis and in early postnatal stages, RGCs acquire gliogenic competence (astrocyte precursor cell (APC) and oligodendrocyte progenitor cell (OPC) for the astrocyte and oligodendrocyte precursor cell, respectively), giving rise to astrocytes and oligodendrocytes. In later postnatal stages, adult neural stem cells (aNSCs) can give rise to neurons or glia. IFE, interfollicular epidermis. HSPCs, haematopoietic stem and progenitor cells.