mesotelencephalen

The mesotelencephalon, sometimes spelled mesotelencephalon, is a historical developmental region of the forebrain in vertebrates. It denotes the ventral portion of the telencephalon that contributes to the formation of subcortical structures associated with the basal ganglia and parts of the limbic system.

During embryogenesis, the telencephalon differentiates into a dorsal pallium and a ventral subpallium. The mesotelencephalon corresponds to this ventral telencephalic region and gives rise to the mature subcortical structures commonly referred to as the basal ganglia, including components such as the caudate nucleus, putamen, and globus pallidus, as well as related limbic-associated nuclei such as the nucleus accumbens and certain septal regions.

In addition to these motor and motivational circuits, the mesotelencephalon helps populate other ventral forebrain structures that interact with cortex and thalamus through complex networks. Its precise boundaries and constituent nuclei are described variably across species and developmental models, reflecting historical changes in terminology.

Today, the term mesotelencephalon is largely historical. Modern neuroanatomy tends to refer to this region as the ventral telencephalon or subpallium, with the mature structures more specifically identified as parts of the basal ganglia and related limbic nuclei. The concept remains useful for understanding embryonic germinal zones and the developmental origins of subcortical circuits.