( ( ( ( Cleavage and ) Implantation ) ( When ( ( a sperm ) ( penetrates ( the egg ) ) ) ) ) ( , ( it ( ( triggers ( the ( egg ( to ( complete meiosis ) ) ) ) ) . ) ) ) )
(ROOT (S (S (NP (NNP Cleavage) (CC and) (NNP Implantation)) (SBAR (WHADVP (WRB When)) (S (NP (DT a) (NN sperm)) (VP (VBZ penetrates) (NP (DT the) (NN egg)))))) (, ,) (NP (PRP it)) (VP (VBZ triggers) (NP (DT the) (NN egg) (S (VP (TO to) (VP (VB complete) (NP (NNS meiosis))))))) (. .)))
Cleavage and Implantation   When a sperm penetrates the egg, it triggers the egg to complete meiosis.
(ROOT (S (NP (NNS Meiosis)) (VP (VBZ is) (NP (NP (NN part)) (PP (IN of) (NP (NP (DT the) (NN process)) (PP (IN of) (NP (NP (NNS gametogenesis)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (NP (NP (DT the) (NN production)) (PP (IN of) (NP (NN sperm) (CC and) (NNS eggs))))))))))))) (. .)))
Meiosis is part of the process of gametogenesis, which is the production of sperm and eggs.