Search results
Results from the WOW.Com Content Network
Before gastrulation, the embryo is a continuous epithelial sheet of cells; by the end of gastrulation, the embryo has begun differentiation to establish distinct cell lineages, set up the basic axes of the body (e.g. dorsal–ventral, anterior–posterior), and internalized one or more cell types including the prospective gut.
Before gastrulation, the cells of the trophoblast become differentiated into two layers: The outer layer forms a syncytium (i.e., a layer of protoplasm studded with nuclei, but showing no evidence of subdivision into cells), termed the syncytiotrophoblast, while the inner layer, the cytotrophoblast, consists of well-defined cells.
Cross section of a vertebrate embryo in the neurula stage. A neurula is a vertebrate embryo at the early stage of development in which neurulation occurs. The neurula stage is preceded by the gastrula stage; consequentially, neurulation is preceded by gastrulation. [1]
As neurulation proceeds after induction, the cells of the neural plate become high-columnar and can be identified through microscopy as different from the surrounding presumptive epithelial ectoderm (epiblastic endoderm in amniotes). The cells move laterally and away from the central axis and change into a truncated pyramid shape.
The mesoderm aids in the production of cardiac muscle, skeletal muscle, smooth muscle, tissues within the kidneys, and red blood cells. The ectoderm produces tissues within the epidermis and aids in the formation of neurons within the brain, and melanocytes. The proceeding graph represents the products produced by the three germ layers.
This neural groove sets the boundary between the right and left sides of the embryo. The neural folds pinch in towards the midline of the embryo and fuse together to form the neural tube. [1] In secondary neurulation, the cells of the neural plate form a cord-like structure that migrates inside the embryo and hollows to form the tube.
Within frogs and fish, however, there exist fundamental differences in how convergent extension is achieved. Frog embryogenesis utilizes cell rearrangement as the sole player of this process. Fish, on the other hand, utilize both cell rearrangement as well as directed migration [1] (Fig. 1) . Cellular rearrangement is the process by which ...
The endoderm consists at first of flattened cells, which subsequently become columnar. It forms the epithelial lining of multiple systems. In plant biology, endoderm corresponds to the innermost part of the cortex in young shoots and young roots often consisting of a single cell layer. As the plant becomes older, more endoderm will lignify.