Technical term in biology and botany for an embryo or germ, such as a plant embryo or wheat germ.
小麦胚芽には栄養が豊富に含まれている。
Wheat germ is rich in nutrients.
植物の胚は種子の中で成長を始める。
The plant embryo begins to grow inside the seed.
germ layer; germinal epithelium
gastrula
embryo sac
embryo
The kanji 胚 is composed of 月 (flesh/body part) and 不 (not), but the historical derivation is uncertain. The reading はい is the on'yomi.