Recent studies support a segmental forebrain bauplan with
three prosomeres (P1–P3) (reviewed in ). Based on morphology
and gene expression the alar plate of the diencephalon is divided
into the prethalamus (P3), thalamus (P2), and pretectum (P1). The
epithalamus including epiphysis and habenular nuclei are part of
 Kiecker C, Lumsden A (2005) Compartments and their boundaries in vertebrate
brain development. Nat Rev Neurosci 6: 553–564.
Developmental relations will be needed for the prosomeres.
alar plate diencephalon