explants

An explant is a fragment of tissue or an organ removed from an organism and used to initiate culture or to study its behavior outside the body. The term applies in both plant biology and animal biology, and the tissue chosen can come from many different organs.

In plant biology, explants are commonly leaf discs, stem segments, roots, or embryos. After surface sterilization, they are placed on nutrient media, often based on Murashige and Skoog formulation, containing growth regulators such as auxins and cytokinins. Depending on the balance of hormones and the genotype, explants may form callus tissue, differentiate into shoots or somatic embryos, or regenerate whole plants. Explant culture allows clonal propagation, genetic transformation, and the study of developmental pathways while maintaining some tissue organization.

Animal explants refer to small pieces of tissue maintained in culture to study cells in a more native microenvironment than isolated cell suspensions. This approach is used in developmental biology, toxicology, cancer research, and pharmacology. Organotypic slice cultures and organ explant cultures preserve aspects of tissue architecture and interactions between cell types, enabling observation of growth, migration, differentiation, or response to treatments. Viability and function depend on culture conditions; explants often require specialized media, supportive matrices, and careful handling to maintain tissue function, and they can be limited by supply, variability, and the loss of vascular and immune components over time.

Ethical and biosafety considerations apply, particularly for vertebrate tissues, and aseptic technique is critical to limit contamination.