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fig 7. CT scan of fetal specimen with a gestational age of 23 weeks 3 days shows persistence of the medial ossification centers of the postsphenoid as separate structures (straight solid arrows). Note the bones of Bertin (open arrow) adjacent to the vomer (v) and rostrum of the basisphenoid. This is the site of sphenoid pneumatization. Note also carotid groove in sphenoid (curved arrow).
fig 8. CT scan of fetal specimen with a gestational age of 21 weeks 4 days shows early ossification of the main centers (solid arrow) and corporal middle centers (open straight arrow) of the presphenoid. Note small defect that represents the remnant of the obliterated craniopharyngeal canal (Rathke's pouch) in the postsphenoid (curved arrow). Asterisk indicates olivary eminence.
fig 9. CT scan of fetal specimen with a gestational age of 24 weeks 4 days shows progressive ossification and fusion of the main (solid arrow) and corporal middle (open arrow) portions of the presphenoid. Note the olivary eminence (asterisk), which is a triangular area filled with unossified cartilage in the presphenoid
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