Floor plate (biology)

Floor Plate (Biology)

Diagram of the developing neural tube

The floor plate is a crucial structure in the developing neural tube of vertebrate embryos. It is located at the ventral midline of the neural tube and plays a significant role in the patterning and differentiation of the central nervous system. The floor plate is involved in the guidance of axons and the establishment of the dorsal-ventral axis in the spinal cord.

Development

The floor plate is induced by signals from the underlying notochord, a rod-like structure that defines the primitive axis of the embryo. The notochord secretes signaling molecules such as Sonic hedgehog (Shh), which are crucial for the induction and patterning of the floor plate. These signals activate specific transcription factors in the ventral neural tube cells, leading to their differentiation into floor plate cells.

Function

The floor plate serves several key functions during neural development:

• Axon Guidance: The floor plate secretes guidance cues that direct the growth of axons across the midline of the nervous system. These cues include molecules such as netrins and slits, which attract or repel growing axons, ensuring proper connectivity between neurons.

• Patterning: The floor plate helps establish the dorsal-ventral patterning of the neural tube by secreting morphogens like Sonic hedgehog. This gradient of signaling molecules influences the fate of progenitor cells in the neural tube, leading to the formation of distinct neuronal subtypes.

• Cell Differentiation: The floor plate influences the differentiation of various cell types in the spinal cord, including motor neurons and interneurons.

Molecular Signaling

Illustration of floor plate signaling

The molecular signaling pathways involved in floor plate development are complex and involve several key players:

• Sonic Hedgehog (Shh): This is the primary signaling molecule secreted by the notochord and floor plate. Shh binds to its receptor, Patched, on target cells, leading to the activation of the Gli transcription factors, which regulate gene expression necessary for cell fate determination.

• Netrins and Slits: These are secreted by the floor plate and play a role in axon guidance. Netrins attract commissural axons to the midline, while slits prevent axons from crossing back once they have crossed the midline.

Clinical Significance

Defects in floor plate development can lead to severe congenital disorders of the nervous system. For example, improper signaling can result in spina bifida or other neural tube defects. Understanding the mechanisms of floor plate development is crucial for developing therapeutic strategies for these conditions.

Related Pages

• Neural tube
• Notochord
• Sonic hedgehog
• Axon guidance
• Spinal cord