The Pediatric Posterior Fossa: an Embryologist's View

Area of Science:

• Developmental biology
• Neuroscience
• Anatomy

Background:

• The paediatric posterior fossa is a complex anatomical region comprising neural and skeletal components.
• Neural elements, originating from the rhombencephalon (hindbrain), form before skeletal elements.
• Rhombomeres, segments of the neural tube, compartmentalize cell migration and gene expression, crucial for development.

Purpose of the Study:

• To review the developmental origins of the paediatric posterior fossa.
• To elucidate the formation of neural structures, particularly the cerebellum, and associated bony elements.
• To discuss the molecular regulation and potential defects in posterior fossa development.

Main Methods:

• Review of developmental processes in the posterior fossa.
• Analysis of neural tube segmentation into rhombomeres.
• Examination of cerebellar development from rhombomere 1 and its fusion.
• Investigation of the mesodermal origin of posterior fossa bony structures.

Main Results:

• Neural structures, including the cerebellum from rhombomere 1, form first, followed by skeletal elements derived from the mesoderm.
• Rhombomere compartmentalization restricts cell migration and specific gene expression, essential for normal development.
• Cerebellar development involves two distinct primordia that fuse at the midline; impaired fusion leads to defects.
• Heterogeneity in molecular processes contributes to the diverse anatomical parts of the cerebellum.

Conclusions:

• The development of the paediatric posterior fossa is a precisely orchestrated process involving neural tube patterning and mesodermal contributions.
• Understanding rhombomere-specific gene expression and cell migration is key to comprehending cerebellar and posterior fossa formation.
• Disruptions in these developmental pathways can lead to significant structural abnormalities in the posterior fossa.