副鼻腔的功能不明，有可能是为了减轻颅骨重量而不损害强度，或者为了加强声音共鸣。
Vice nasal whose function, it could be a skull to reduce weight, but does not damage intensity, or in order to strengthen the voice resonated.
虽然从胎盘的重量和营养看，胎盘好象起到重要的作用，但是调控胎盘催乳素分泌的确切因素尚不明确。
The precise factors that modulate secretion of are unknown, although placental mass and nutrition seem to play a role.
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