End- or Endo- Biology Prefixes and Suffixes

The prefix (end- or endo-) means within, inside or internal. Examples Endobiotic (endo-biotic) - referring to a parasite or symbiotic organism that lives within the tissues of its host. Endocardium (endo-cardium) - inner membrane lining of the heart that also covers heart valves and is continuous with the inner lining of blood vessels. Endocarp (endo-carp) - the hard inner layer of pericarp that forms the pit of ripened fruit. Endocrine (endo-crine) - refers to the secretion of a substance internally. It also refers to glands of the endocrine system that secrete hormones  directly into the blood. Endocytosis (endo-cytosis) - transport of substances into a cell. Endoderm (endo-derm) - inner germ layer of a developing embryo that forms the lining of the digestive and respiratory tracts. Endoenzyme (endo-enzyme) - an enzyme that acts internally to a cell. Endogamy (endo-gamy) - internal fertilization between flowers of the same plant. Endogenous (endo-genous) - produced, synthesized or caused by factors within an organism. Endolymph (endo-lymph) - the fluid contained within the membranous labyrinth of the inner ear. Endometrium (endo-metrium) - inner mucous membrane layer of the uterus. Endomitosis (endo-mitosis) - a form of internal mitosis in which chromosomes replicate, however the division of the nucleus and cytokinesis do not occur. It is a form of endoreduplication. Endomixis (endo-mixis) - reorganization of the nucleus that occurs within the cell in some protozoans. Endomorph (endo-morph) - an individual with a heavy body type predominated by tissue derived from the endoderm. Endophyte (endo-phyte) - a plant parasite or other organism that lives within a plant. Endoplasm (endo-plasm) - the inner portion of the cytoplasm in some cells such as protozoans. Endorphin (endo-dorphin) - a hormone produced within an organism that acts as a neurotransmitter to reduce the perception of pain. Endoskeleton (endo-skeleton) - an organisms internal skeleton. Endosperm (endo-sperm) - tissue within the seed of an angiosperm that nourishes the developing plant embryo. Endospore (endo-spore) - an inner wall of a plant spore or pollen grain. It also refers to a non-reproductive spore produced by some bacteria and algae. Endothelium (endo-thelium) - thin layer of epithelial cells that form the inner lining of blood vessels, lymphatic vessels and heart cavities. Endotherm (endo-therm) - an organism that generates heat internally to maintain constant body temperature.