Face arises early

Neural crest cells form sooner and more independently than expected

Cervical embryo with red-labeled neural crest precursor cells © Martín García-Castro
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Our face is made of cells and tissues during embryonic development, as are all other body parts. Now, scientists have discovered that the precursors to the head, neck, and head and neck nerve centers form much earlier than previously thought, and do so without interacting with other tissues. This reports a study now published in "Nature".

Scientists at Yale University and California Institute of Technology (Caltech) demonstrated using three equally different technologies that the formation of the cells of the so-called neural crest in chicken embryos is independent of mesodermal tissue - the source of all connective tissue and muscle - as well as neural Tissues is. The neural crest is a group of stem cells that migrate strongly during embryonic development, producing numerous tissues, including bone and cartilage of the skull, skin pigment cells, and peripheral nervous system cells. If the development of these cells is disturbed, this leads to human malformations such as harelip, heart valve malformations and several types of tumors.

But so far, the genesis and the exact course of normal development of this cell group have not been known exactly. Based on findings from the 1940s, it was assumed that the neural crest is formed by interactions between neural and non-neural cell layers.

Chicken embryos as a model

The researchers used chicken embryos as experimental objects, as these represent a well-suited model for the developmental biology of vertebrates. It was clear that the ability of embryos to form neural crest cells rapidly dropped after the so-called "stage 10". The scientists were now looking for the conditions at which this cell group is first formed in the embryo. To do this, they took cell samples from various body regions from a very early stage, in which the neural plate - precursor structures of the nervous system - was not yet formed, placed them with a specific marker and kept them in culture.

Neural crest cells created earlier than expected

Surprisingly, certain regions of the embryo formed both the migrating neural crest cells and the cell types emanating from them - without mesodermal or neural tissue being available. "In this work, we show that neuralkaline stem cell precursors are applied very early in development - even in the gastrula - regardless of the influence of other tissues, " explains Martín García-Castro, Assistant Professor of Molecular, Cellular and Developmental Biology at Yale University. display

"Our findings contradict current textbook opinions and suggest that several mechanisms of neural crest induction are active during development. The mechanism we have discovered is related to early neural crest cells, the only ones that still retain the potential for bone and cartilage formation in the higher vertebrates.

"Understanding the origin of the neuralkyric cells - how, when, and how they are formed - is a crucial step in trying to manipulate them for therapeutic purposes, " Garc said a-Castro. "The importance of these fundamental questions of biology and development goes far beyond these chickens and eggs."

(Yale University, July 12, 2006 - NPO)