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Updated: Nov 7, 2025

The Mouse Hindbrain As a Model for Studying Embryonic Neurogenesis
Published on: January 29, 2018
The hypothalamus predates the origin of vertebrates
Laurence A Lemaire1, Chen Cao1, Peter H Yoon2
1Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA.
Abstract:
The hypothalamus coordinates neuroendocrine functions in vertebrates. To explore its evolutionary origin, we describe integrated transcriptome/connectome brain maps for swimming tadpoles of Ciona, which serves as an approximation of the ancestral proto-vertebrate. This map features several cell types related to different regions of the vertebrate hypothalamus, including the mammillary nucleus, the arcuate nucleus, and magnocellular neurons. Coronet cells express melanopsin and share additional properties with the saccus vasculosus, a specialized region of the hypothalamus that mediates photoperiodism in nontropical fishes. Comparative transcriptome analyses identified orthologous cell types for mechanosensory switch neurons, and VP and VPR relay neurons in different regions of the mouse hypothalamus. These observations provide evidence that the hypothalamus predates the evolution of the vertebrate brain. We discuss the possibility that switch neurons, coronet cells, and FoxP /VPR relay neurons comprise a behavioral circuit that helps trigger metamorphosis of Ciona larvae in response to twilight.
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