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Sectioned foetus. Midsagittal section through the head of a 22-week-old foetus, revealing the internal organs. The foetus' facial structure is seen (down left) and the tongue (lower left) can be seen filling the oral cavity. The brain (upper centre) has developed to a stage where the foetus is aware of maternal sounds. The cerebellum (lower right) that controls motor function, and the pons (centre), the origin of cranial nerves, are both clearly seen. (KEYSTONE/SCIENCE PHOTO LIBRARY/DR G. MOSCOSO)