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Updated: Jul 13, 2026
10:34
Activity of Posterior Lateral Line Afferent Neurons during Swimming in Zebrafish
Published on: February 10, 2021
Lateral line, otic and epibranchial placodes: developmental and evolutionary links?
Clare V H Baker1, Paul O'Neill, Ruth B McCole
1Department of Physiology, Development and Neuroscience, Anatomy Building, Downing Street, Cambridge, United Kingdom. cvhb1@cam.ac.uk
Summary
This review explores potential links between lateral line and epibranchial placodes, crucial for vertebrate sensory systems. We propose these placodes may have evolved from a common ancestor involved in protective reflex circuits.
Area of Science:
- Developmental biology
- Evolutionary biology
- Neuroscience
Background:
- Cranial ectodermal placodes are key embryonic cell populations in vertebrates.
- Neurogenic placode derivatives are essential for sensing external and internal stimuli.
- Lateral line and epibranchial placodes are typically studied as independent structures.
Purpose of the Study:
- To discuss potential developmental and evolutionary relationships between lateral line and epibranchial placodes.
- To explore the origin of the spiracular/paratympanic organ.
- To propose a hypothesis on the ancestral function of placodal cells.
Main Methods:
- Speculative review integrating existing knowledge.
- Illustration of placode development using molecular data from shark embryos.
- Comparative analysis of placode derivatives and their functions.
Main Results:
- Lateral line placodes form sensory systems in anamniotes.
- Epibranchial placodes generate visceral sensory neurons (Phox2b+).
- The geniculate placode may contribute to the spiracular/paratympanic organ.
Conclusions:
- Lateral line, epibranchial, and otic placodes may share developmental and evolutionary connections.
- These placodes are important for protective somatic reflexes.
- An ancestral function involving Phox2b-dependent protective reflex circuits is proposed.
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