Terms used in tissue culture

Aseptic -- Free from microorganisms

Callus -- Undifferentiated, swollen cell mass forming under the influence of elevated plant hormone levels.

Etiolation -- Yellow and stretched plant; parts elongate until light is intercepted.

Explant -- Part of an organism used in "in vitro" culture.

IAA -- Indole acetic acid; a plant hormone increasing cell elongation and, under certain circumstances, implicated in stimulating cell division and root formation. IAA moves in a polar manner in plants forming an IAA gradient in tissues. Orientation of plant organs, then, influence callus formation and morphogenesis.

"in vitro" -- "In glass"; as in tissue culture methods

Morphogenesis -- Change in shape

Polarity -- Orientation in gravitational field.

Primordia -- The earliest detectable stage of an organ, such as a leaf, root or root branch.

Root hairs -- Epidermal cell extensions of young root that increase absorptive surface area.

Totipotency -- The establishment of missing plant organs or parts; formation of a whole plant from a few cells or small portion of a plant.

Wound response -- Formation of callus in wounded area.