Knockdown of Oyvlg by RNAi resulted in germ cell underproliferation and prematurely arrested meiosis, indicating a key role of vasa in bivalve germ cell development [38 ,39 ].
Meaning of prematurely for the defined word.
Grammatically, this word "prematurely" is an adverb. It's also a morpheme, more specifically, a suffixe.