Glossary of plant morphology others may form a tight spiral, or whorl, around the flower stem. First, at the base, are those non-reproductive structures involved in protecting the flower when it is still a bud, the sepals, then are those parts that play a role in attracting pollinators and are typically coloured, the petals, which together with the sepals make up the perianth (perigon, perigonium). If the perianth is differentiated, the outer whorl of sepals forms the calyx, and the inner whorl of petals, the corolla. If the perianth is not differentiated into sepals and petals, they are collectively known as tepals. In some
Calyx of Held a mature calyx that facilitates the consistent, rapid spread of signals in the MNTB-VCN area. A select few processes occur during early neuronal development in order to ensure proper calyx formation, specifically through the influence of Fibroblastic Growth Factor (FGF), transcription factor Math5, neural cell recognition molecule NB-2, and ephrin (Eph) proteins in cells. Math1/Math5 and FGF are two regulators essential for appropriate growth and development of the cochlear nucleus complex, which comprises both the ventral cochlear nucleus (VCN) and the dorsal cochlear nucleus (DCN). Sufficient FGF levels ensure proper morphology of the cochlear nuclei, while Math5 insures correct size