Differentiationsvägar

Differentiationsvägar is a term used in developmental biology to describe the sequences of cellular decisions and gene expression changes that guide a progenitor or stem cell toward a specialized cell fate. These pathways can be linear, where a cell follows a single succession of states, or branching, where different lineages emerge from common intermediates. They may be multi-step and, in principle, reversible, reflecting the dynamic nature of cell fate decisions. The concept emphasizes the interplay between intrinsic genetic programs and extrinsic signals from the cellular environment that influence differentiation.

Mechanisms shaping differentiationsvägar include transcriptional networks, epigenetic states, and signaling cues such as Notch, WNT, SHH, and various cytokines. Transcription factors act as fate determinants, while epigenetic modifications stabilize lineage choices. Stochasticity and tissue context contribute to heterogeneity, allowing cells with similar origins to diverge into distinct fates.

Examples include hematopoiesis, where hematopoietic stem cells differentiate into myeloid or lymphoid lineages and subsequently into erythrocytes, platelets, and various immune cells; neural differentiation, wherein neural progenitors produce neurons, astrocytes, or oligodendrocytes; and epithelial differentiation guided by morphogen gradients and cell–cell interactions.

Research and applications rely on methods such as single-cell transcriptomics, lineage tracing, and trajectory inference to reconstruct differentiation paths. Insights from differentiationsvägar underpin regenerative medicine, cancer biology, and the study of developmental disorders. The Waddington landscape remains a common metaphor for illustrating how signaling networks and gene regulation shape differentiation paths. See also Developmental biology; Cellular differentiation; Lineage tracing; Trajectory inference.