胚子 is read as はいし (haishi) and means embryo.
はいし
haishi
さいし
wife
おやこ
parent and child
ふたご
twins
でし
pupil
とうがらし
shichimi pepper
ぎょーざ
gyoza
ぼし
mother and child
なす
eggplant (Solanum melongena)
ちょうし
trend
ようす
sign
りし
interest (on a deposit, loan, etc.)
ようし
adopted child (usu. male)