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Fig. 2. Stage 28: Dark-field and bright-field
photomicrographs showing (A) the onset of POMC
expression, and (B) the relationship of the pituitary
primordium (HP) to the embryonic forebrain (FB).
(A) Coronal section from head (level shown below)
showing the first evidence of POMC mRNA (arrow) in the
posterior end of the translocating pituitary plate at the
juncture of diencephalon and infundibulum ventral to
posterior diencephalon (pDI) and optic vesicles (OV).
(B) Sagittal section through forebrain (anterior is to the
right) showing the anterior-to-posterior extent of the
translocating pituitary plate (HP, arrowheads) between
diencephalon (DI), infundibulum (IF), foregut (FG) and
cement gland (CG). The anterior trailing end is shown
extending to its origin in the stomodeum (S), and the
leading end of the plate does not yet occupy (as in Fig. 5)
the region beneath the juncture of the thicker diencephalic
(long arrow) and thinner infundibular (short arrow) walls.
POMC mRNA was first detected in sections at this level in
pituitary plate at stage 28 (above), and in brain at stage
29/30 (Fig. 3A). Note the plate is connected to brain floor
at attachment sites. Calibration bars are 100um. |
