Key facts
- Vertebrate nervous systems develop in four major segments: forebrain, midbrain, hindbrain, and spinal cord.
- Neural cells form from a thickening of the ectoderm, which then folds into a tube.
- New research used genetically modified mice with red and cyan fluorescent proteins to trace cell development.
- The study found that inherited positional information from the ectoderm sets boundaries for brain segments.
- In 96% of cases, descendants of single early ectoderm cells were all in the hindbrain or all in the midbrain/forebrain.
- Similar results were observed using human stem cells, demonstrating the role of positional information in neural development.
New research is clarifying how vertebrate nervous systems develop, specifically addressing the segmentation of the brain. Contrary to some sensationalized reports, the study does not suggest humans have two brains but rather illustrates the fundamental processes of developmental biology. The research focuses on how early positional information inherited by cells dictates their fate in forming distinct brain segments.
Vertebrate embryos develop with four major nervous system segments: the forebrain, midbrain, hindbrain, and spinal cord. Neural cells originate from a thickening of the ectoderm, which then folds to form a tube. The question of how these segments form has been a long-standing focus in developmental biology.
To investigate this, researchers engineered mice where specific ectoderm cells glowed red or cyan. These colors were maintained as the embryo developed into nerve cells and brain structures. The findings indicated that inherited positional information from the ectoderm establishes key boundaries within the developing brain, determining whether cells are destined for the hindbrain or the midbrain and forebrain.
Further experiments using similar genetic tools showed that in 96% of cases, the descendants of a single early ectoderm cell all belonged to either the hindbrain or the midbrain and forebrain. The study also utilized human stem cells, demonstrating that exposure to the correct signals directs stem cells to adopt specific neural fates, with nerve cells inheriting this positional information.