During development, from which midline region do the callosal fibers originate to cross to the opposite hemisphere?

During development, from which midline region do the callosal fibers originate to cross to the opposite hemisphere?

• A. Dorsal thalamus
• B. Ventral midline
• C. Commissural plate (callosal plate)
• D. Lateral ventricles

Answer: (C)

Callosal fibers come from cortical neurons in the dorsal telencephalon and grow toward the ventral midline to cross into the opposite hemisphere. This crossing happens at a specialized midline region called the commissural plate (callosal plate), where glial scaffolding guides the axons to cross and form connections that become the corpus callosum. Other regions like the dorsal thalamus, ventral midline, or lateral ventricles are not the crossing site for these commissural fibers.

Callosal fibers come from cortical neurons in the dorsal telencephalon and grow toward the ventral midline to cross into the opposite hemisphere. This crossing happens at a specialized midline region called the commissural plate (callosal plate), where glial scaffolding guides the axons to cross and form connections that become the corpus callosum. Other regions like the dorsal thalamus, ventral midline, or lateral ventricles are not the crossing site for these commissural fibers.