Section of the pituitary gland of a monkey, stained with haematoxylin and eosin. In the middle is seen a well-marked cleft (A), the rudiment of the lumen of Rathke‘s pouch. To the left is the pars nervosa or posterior lobe (B), and to the right the pars distalis or anterior lobe (C). Separating the posterior lobe from the central cleft is a thin layer of tissue, the pars intermedia (D). The photograph is at a magnification of X 34.

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