胚芽[haiga] germ (of a cereal, e.g. wheat, rice)
胚子[haishi] embryo
胚珠[haishu] ovule
胚胎[haitai] germination
胚乳[hainyuu] albumen (of a seed, esp. the endosperm)

胚葉[haiyou] germ (germinal, embryonic) layers
外胚葉[gaihaiyou] ectoderm
胚性幹細胞[haiseikansaibou] embryonic stem cell
胚性[haisei] embryonic

花芽[kaga] flower bud
芽ぐむ[megumu] to bud
芽生え[mebae] bud
芽生える[mebaeru] to bud
芽胞[gahou] spore

御芽出度う[omedetou] congratulations!
歯芽[shiga] tooth germ
出芽[shutsuga] germination
新芽[shinme] sprout