The International journal of developmental biology最新文献

The gastrointestinal tract is an essential system of organs required for nutrient absorption. As a simple tube early in development, the primitive gut is patterned along its anterior-posterior axis into discrete compartments with unique morphologies relevant to their functions in the digestive process. These morphologies are acquired gradually through development as the gut is patterned by tissue interactions, both molecular and mechanical in nature, involving all three germ layers. With a focus on midgut morphogenesis, we review work in the chick embryo demonstrating how these molecular signals and mechanical forces sculpt the developing gut tube into its mature form. In particular, we highlight two mechanisms by which the midgut increases its absorptive surface area: looping and villification. Additionally, we review the differentiation and patterning of the intestinal mesoderm into the layers of smooth muscle that mechanically drive peristalsis and the villification process itself. Where relevant, we discuss the mechanisms of chick midgut morphogenesis in the context of experimental data from other model systems.

Some 25 years ago, a clone was identified that contained the chicken Slug sequences (now called Snail2 ). How could we anticipate at that time how much the chick embryo would help us to understand the ins and outs of cell migration during development and in disease? Indeed, the chick embryo helped us identify Snail2 as the first transcription factor that could induce the epithelial-mesenchymal transition (EMT), key for the migration of embryonic and cancer cells.

Here, I provide some recollections of my life, starting as a civil engineer in South Africa and how I gradually became interested in biology, particularly pattern formation. In retrospect, I think that my decision to work on chick embryos to study limb development back in 1966 turned out to be the right one. The principles discovered in these 50 years, both by my collaborators and by other colleagues, have established the principles of how the limb develops in higher vertebrates, including humans.

The neural crest is a multipotent and highly migratory cell type that contributes to many of the defining features of vertebrates, including the skeleton of the head and most of the peripheral nervous system. 150 years after the discovery of the neural crest, avian embryos remain one of the most important model organisms for studying neural crest development. In this review, we describe aspects of neural crest induction, migration and axial level differences, highlighting what is known about the underlying gene regulatory mechanisms. Past and emerging technologies continue to improve the resolution with which we can examine important questions of neural crest development, with modern avian molecular embryology continuing to make important contributions.

Sensory placodes contribute to much of the sensory nervous system in the vertebrate head. They give rise to parts of the eye, ear and nose, as well as to the sensory ganglia that innervate the face, tongue, oesophagus and visceral tissues. Despite their diversity, during development placodes arise from a population of common progenitor cells, which are first specified at the border of the neural plate. The chick has been particularly instrumental in dissecting the timing of these events, and recent evidence has highlighted the close relationship of placode progenitors and precursors for neural crest cells and the central nervous system. This review focuses on the induction of placode progenitors by localised signalling events, and the transcriptional networks that lead to their specification.

Birds and mammals, both being amniotes, share many common aspects of development. Thus our understanding of how limb-innervating mammalian spinal motor circuits develop was greatly influenced by the use of the avian embryo (chick/quail) to bring about experimental perturbations to identify basic underlying mechanisms. These included embryonic surgery, the application of drugs to influence activity or molecular interactions, and the ability to observe motor behavior and make physiological recordings in intact developing embryos. This article will review some of these contributions, highlighting several areas including the acquisition of motoneuron subtype identity and target selection, as well as the role of spontaneous rhythmic activity in circuit development.