What is "basal plate"

During pregnancy changes in the placenta involve the disappearance of the greater portion of the stratum compactum, but the deeper part of this layer persists and is condensed to form what is known as the basal plate. Between this plate and the uterine muscular fibres are the stratum spongiosum and the boundary layer; through these and the basal plate the uterine arteries and veins pass to and from the intervillous space.

Basal plate may refer to:

• Basal plate (neural tube), the region of the neural tube ventral to the sulcus limitans
• Basal plate (placenta), between this plate and the uterine muscular fibres are the stratum spongiosum and the boundary layer
• The base of a plant's bulb
• The pedal disc, in anatomy of the sea anemone, the surface opposite to the mouth
• The region if electron density at which the central microtubule pair are nucleated in the eukaryotic flagellum axoneme

In the developing nervous system, the basal plate is the region of the neural tube ventral to the sulcus limitans. It extends from the rostral mesencephalon to the end of the spinal cord and contains primarily motor neurons, whereas neurons found in the alar plate are primarily associated with sensory functions. The cell types of the basal plate include lower motor neurons and four types of interneuron.

Initially, the left and right sides of the basal plate are continuous, but during neurulation they become separated by the floor plate, and this process is directed by the notochord. Differentiation of neurons in the basal plate is under the influence of the protein Sonic hedgehog released by ventralizing structures, such as the notochord and floor plate.