| BRAIN | Section No. 68 |  
       Form and size of the brain at stage 13.  | 
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 Text and Drawing adapted from Fig 13-10 of O'Rhailly, R., and Müller, F.. Developmental Stages in Human Embryos, Carnegie Institution of Washington, Publication 637, 1987.] 
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       Various neural areas are indicated according to current interpretations. A section (at higher magnification) through the midbrain at the level marked A-B shows the appearance of the neural wall at this time.Based on reconstructions by Osborne O. Heard.  | 
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