Rhombomere

Rhombomere is a transverse segment of the developing vertebrate hindbrain. The hindbrain, also known as the rhombencephalon, is divided into eight rhombomeres during early embryonic development. Each rhombomere gives rise to specific structures in the mature brain and has a distinct genetic expression pattern.

Development

Rhombomeres are formed during the process of neurulation, when the neural tube is being formed. The hindbrain region of the neural tube develops a series of constrictions, dividing it into eight segments. These segments are numbered from anterior to posterior, with rhombomere 1 being the most anterior and rhombomere 8 the most posterior.

Function

Each rhombomere has a unique identity and gives rise to specific structures in the mature brain. For example, rhombomere 4 gives rise to the facial nerve, while rhombomere 6 gives rise to the abducens nerve. The unique identity of each rhombomere is determined by the specific combination of Hox genes that are expressed in that segment.

Clinical significance

Abnormalities in rhombomere development can lead to a variety of neurological disorders. For example, DiGeorge syndrome is caused by a deletion of a region on chromosome 22 that includes several Hox genes. This results in abnormal development of the hindbrain and associated structures, leading to symptoms such as heart defects, facial abnormalities, and learning difficulties.

See also

• Neurulation
• Hox genes
• DiGeorge syndrome