The metencephalon
is the more rostral component of the hindbrain and develops into 2 parts,
the pons and
cerebellum. The pons
consists of 2 parts: a) the phylogenetically older dorsal portion called the
pontine tegmentum which lies in the floor of the 4th ventricle and is
continuous with the medulla and exhibits a similar organization and b) the
phylogenetically newer basis pontis which develops later.
Alar plates (yellow)
and
basal plates (red),
with their afferent and efferent nuclei, lie medial and lateral to the
sulcus limitans,
respectively. Cortically-originating fibers synapse on
nuclei of the basis pontis
(which migrate there from the alar plate).
