noun
ontogeny; ontogenesis
Technical biology term for the development of an individual organism from embryo to mature form.
個体発生は系統発生を繰り返すと言われる。
It is said that ontogeny recapitulates phylogeny.
系統発生 refers to phylogeny (evolutionary development of a species), while 個体発生 refers to ontogeny (development of an individual organism).
Compound of 個体 (individual, organism) and 発生 (development, occurrence). A calque from German 'Ontogenie' or English 'ontogeny'.