ventral midline development

Definition

Target type: biologicalprocess

The process whose specific outcome is the progression of the ventral midline over time, from its formation to the mature structure. In protostomes (such as insects, snails and worms) as well as deuterostomes (vertebrates), the midline is an embryonic region that functions in patterning of the adjacent nervous tissue. The ventral midline in insects is a cell population extending along the ventral surface of the embryo and is the region from which cells detach to form the ventrally located nerve cords. In vertebrates, the midline is originally located dorsally. During development, it folds inwards and becomes the ventral part of the dorsally located neural tube and is then called the ventral midline, or floor plate. [GOC:bf, GOC:go_curators, PMID:12075342]

Ventral midline development is a complex and intricate process that establishes the foundation for the formation of the ventral midline structures in an organism. This process involves a series of precisely coordinated cellular events, including cell migration, differentiation, and signaling, which ultimately give rise to vital structures such as the notochord, floor plate, and ventral spinal cord.

**Initiation of Ventral Midline Development:**

The ventral midline development begins with the establishment of the organizer, a region of cells that plays a crucial role in patterning the embryo along the dorsal-ventral axis. In vertebrates, the organizer is known as the Spemann-Mangold organizer and is located at the dorsal lip of the blastopore. The organizer secretes signaling molecules, such as Nodal and BMP4, that induce the formation of the ventral midline.

**Formation of the Notochord:**

The notochord is a rod-shaped structure that forms along the ventral midline of the embryo. It arises from the mesoderm, a germ layer that gives rise to muscles, bones, and other connective tissues. Cells in the organizer induce mesoderm cells to adopt a notochordal fate. The notochord plays a critical role in axial elongation, vertebral column formation, and the establishment of the dorsal-ventral axis.

**Formation of the Floor Plate:**

The floor plate is a specialized structure that forms at the ventral midline of the neural tube. It is induced by signals from the notochord, particularly Shh. The floor plate acts as a signaling center that pattern the ventral spinal cord, regulating the development of motor neurons and other cell types.

**Signaling Pathways Involved in Ventral Midline Development:**

* **Sonic hedgehog (Shh) signaling:** Shh is a secreted morphogen that plays a central role in patterning the ventral midline. It is secreted by the notochord and floor plate and acts as a concentration gradient to induce the formation of different cell types in the ventral spinal cord.
* **Bone morphogenetic protein (BMP) signaling:** BMPs are a family of secreted signaling molecules that are involved in various developmental processes, including ventral midline development. BMP signaling is crucial for the formation of the notochord and the patterning of the dorsal spinal cord.
* **Wnt signaling:** Wnt signaling is another important pathway that regulates ventral midline development. Wnt signaling is involved in the formation of the floor plate and the patterning of the ventral spinal cord.

**Disruption of Ventral Midline Development:**

Defects in ventral midline development can lead to a range of birth defects, including spina bifida, anencephaly, and holoprosencephaly. These defects can arise from mutations in genes that encode signaling molecules or their receptors, as well as from environmental factors that disrupt normal development.

In summary, ventral midline development is a tightly regulated process that involves a complex interplay of signaling pathways, cell migration, and differentiation. This process is crucial for the formation of essential structures that underlie the proper development of the central nervous system and the axial skeleton.'
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Proteins (3)

Compounds (13)