Explant

An explant is a small piece of tissue or an organ removed from its original organism for study, culture, or transplantation. In biology, explants preserve some of the architecture and cell–cell interactions of the intact tissue, offering a compromise between isolated cell culture and whole-organism experiments. They are used to investigate development, physiology, pathology, and responses to drugs.

In plant science, explants such as leaf discs, stem segments, roots, or embryos are cultured on nutrient media. With growth regulators such as auxins and cytokinins, explants can form callus tissue, differentiate into shoots and roots, and regenerate whole plants, a process known as micropropagation. Explant choice and culture conditions influence regeneration, genetic stability, and propagation efficiency.

In animal and human research, tissue explants (for example brain, liver, or tumor slices) are maintained ex vivo to study responses to drugs, toxicants, or disease processes while preserving tissue context. Clinically, the term explant may also describe a biopsy specimen removed for diagnostic examination, or the surgical removal of an implanted device or graft.

Explantation in a medical sense refers to the removal of an implanted device or transplanted tissue. Indications include infection, device failure, adverse tissue reaction, or planned replacement. Procedures require appropriate anesthesia or aseptic technique, careful dissection, and post-procedural assessment; explanted material is often evaluated histologically.

Ethical considerations include informed consent for human tissue use and compliance with regulatory and biosafety guidelines. See also explantation and tissue culture.