Rohon–Beard cell

Rohon–Beard cells are specialized sensory neurons that are found in the embryonic stages of some vertebrates, including fish and amphibians. These cells are named after the scientists Josef Rohon and Charles Beard who first described them. Rohon–Beard cells are primarily involved in the sensation of touch and pressure in the early development stages before the maturation of the dorsal root ganglia.

Function

Rohon–Beard cells are responsible for mediating the sense of touch and pressure in embryonic vertebrates. They are mechanosensory neurons, meaning they convert mechanical stimuli into electrical signals that the nervous system can interpret. These cells are crucial for the survival of embryos as they help them respond to environmental stimuli.

Development

Rohon–Beard cells originate from the neural crest, a group of cells in the developing embryo that also gives rise to other cell types such as melanocytes and some types of neurons and glia. During development, Rohon–Beard cells migrate to the dorsal part of the spinal cord, where they extend processes that reach the skin and other tissues to sense mechanical stimuli.

Morphology

The morphology of Rohon–Beard cells is characterized by their large size and the presence of extensive dendritic processes that allow them to cover a significant area and detect mechanical stimuli. These cells are pseudo-unipolar neurons, meaning they have a single process that divides into two branches, one acting as a dendrite and the other as an axon.

Physiology

Upon sensing mechanical stimuli, Rohon–Beard cells generate action potentials that are transmitted to the central nervous system. This allows the embryo to react to touch and pressure, facilitating protective reflexes and other responses to the environment.

Evolutionary Significance

The presence of Rohon–Beard cells in only certain vertebrates suggests an interesting aspect of evolutionary development. In species where these cells are present, they play a crucial role during embryonic stages but are typically replaced by other sensory systems as the organism matures. This transition reflects the evolutionary adaptation of sensory systems to the needs of the organism at different stages of life.

Clinical Significance

While Rohon–Beard cells are not present in human embryos, studying them can provide insights into the development and function of sensory neurons and the neural crest. Understanding the mechanisms that govern the development and function of these cells can contribute to the knowledge of sensory neuron pathologies and the development of therapeutic strategies.