This change in morphology is associated with important physical and cytochemical changes and with an increase in their capacity for motility and their fertilizing ability. 這種形態學的變化是與重要的物理學和組織化學的變化以及活力和受精能力的增強有關。
When it is not, then availability of IVF depresses the birth rate because women balance the cost of a child against the extra income they could earn in employment outside the home. 當它得不到巨額補助的時候，試管受精便使生育率越發低下，因為婦女會對生育孩子的成本和她們在外受雇所掙的額外收入進行比較。
