Olfactory sensory system develops from coordinated movements within the neural plate

Abstract

Background The peripheral olfactory sensory system arises from morphologically identifiable structures called placodes. Placodes are relatively late developing structures, evident only well after the initiation of somitogenesis. Placodes are generally described as being induced from the ectoderm suggesting that their development is separate from the coordinated cell movements generating the central nervous system. Results With the advent of modern techniques it is possible to follow the development of the neurectoderm giving rise to the anterior neural tube, including the olfactory placodes. The cell movements giving rise to the optic cup are coordinated with those generating the olfactory placodes and adjacent telencephalon. The formation of the basal lamina separating the placode from the neural tube is coincident with the anterior migration of cranial neural crest. Conclusions Olfactory placodes are transient morphological structures arising from a continuous sheet of neurectoderm that gives rise to the peripheral and central nervous system. This field of cells is specified at the end of gastrulation and not secondarily induced from ectoderm. The separation of olfactory placodes and telencephalon occurs through complex cell movements within the developing neural plate similar to that observed for the developing optic cup.

Extrinsic mechanical forces mediate retrograde axon extension in a developing neuronal circuit

“…1a, b ) 16 . Despite recent imaging efforts 21 , 22 , we still lack a high-resolution analysis of cell behaviours during this morphogenetic event. We took advantage of the ngn1 : gfp line 23 that labels a subpopulation of OP cells known as the early-born neurons, which include pioneer neurons 18 .…”

“…1c, d , left panels ), and expressing Dlx3b (Supplementary Fig. 1a ), a marker for OP cells 21 , 22 . At 24 s, ngn1 : gfp + cells formed paired ellipsoidal clusters next to the brain.…”

Sensory evolution in blind cavefish is driven by early embryonic events during gastrulation and neurulation

“…The placodes correspond to a region surrounding the neural plate that generates the sensory organs of the head in vertebrates, including the lens, the olfactory epithelium, the otic vesicle and the lateral line (Schlosser, 2006;Streit, 2007Streit, , 2008Torres-Paz and Whitlock, 2014;Whitlock and Westerfield, 2000). Here, we investigated the development of the Astyanax CF placodal region, with a particular focus on the lens and olfactory placodes.…”

The loss of scents: Do defects in olfactory sensory neuron development underlie human disease?

“…B, red) that eventually surrounded the formed olfactory organ an eye (Fig. C, green; (Torres‐Paz and Whitlock, ). The morphogenesis of the olfactory system was observed in the same time window as the morphogenetic movements underlying the formation of the optic cup (see for review: (Cavodeassi, ).…”

“…In contrast, in the new model, the op and ob develop as a neurectodermal unit (brown), much like the retina of the eye and the post‐synaptic targets in the tectum (blue). Modified from (Torres‐Paz and Whitlock, ). ( B ) Image of anterior neural plate as neural crest cells (red, arrow) migrate anteriorly to separate the peripheral (op) from the central (nt) olfactory sensory system, resulting in a head with the eye (retina, r; lens, l) and olfactory placode surrounded by neural crest cells (green).…”