One of the minute grains in flowerless plants, which are analogous to seeds, as serving to reproduce the species.

An embryo sac or embryonal vesicle in the ovules of flowering plants.

A minute grain or germ; a small, round or ovoid body, formed in certain organisms, and by germination giving rise to a new organism; as, the reproductive spores of bacteria, etc.

Specialized reproductive bodies or resting cells that resist adverse conditions which would readily destroy the parent organism.

a hard casing that contains the genetic material of those bacteria and other microorganisms that are able to form the structure

a survival structure and this will then give rise to a new bacillus and this is all very simple, a very nice idea of bacteriology

(or Endospore)—A structure formed by the actively growing (vegetative) stage of some bacteria that is able to remain viable under extremely harsh environmental conditions (heat, dryness, radiation) and, when the environment improves, once again actively grow and proliferate. As used in the context of planetary protection and in its appropriate requirements and specifications, spore refers to a heat-shock surviving microbe culturable in the NASA standard assay.

Encapsulated, resistant form of a microorganism.