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Epiboly in zebrafish is the first coordinated cell movement, beginning at the dome stage late in the blastula period and continuing throughout gastrulation. [3] At this point the zebrafish embryo contains three portions: an epithelial monolayer known as the enveloping layer (EVL), a yolk syncytial layer (YSL) which is a membrane-enclosed group of nuclei that lie on top of the yolk cell, and ...
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. [2]
The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). [1] It emerges and originates from the outer layer of germ cells.
The axons of midget cells travel through the optic nerve and optic tract, ultimately synapsing with parvocellular cells in the LGN. These cells are known as midget retinal ganglion cells due to the small sizes of their dendritic trees and cell bodies. About 80% of RGCs are midget cells. They receive inputs from relatively few rods and cones.
The endoderm is one of the germ layers formed during animal embryogenesis. Cells migrating inward along the archenteron form the inner layer of the gastrula, which develops into the endoderm. Initially, the endoderm consists of flattened cells, which subsequently become columnar...
The inner layer of the optic cup is made of neuroepithelium (neural retina), while the outer layer is composed of retinal pigment epithelium (RPE). Experiments have determined that RPE cell differentiation and maintenance requires interaction with neighboring tissues, most likely canonical Wnt signaling, while neural retina differentiation is ...
The other two layers are the ectoderm (outside layer) and mesoderm (middle layer). [1] Cells migrating inward along the archenteron form the inner layer of the gastrula, which develops into the endoderm. [2] The endoderm consists at first of flattened cells, which subsequently become columnar. It forms the epithelial lining of multiple systems.
The epiblast was first discovered by Christian Heinrich Pander (1794-1865), a Baltic German biologist and embryologist. With the help of anatomist Ignaz Döllinger (1770–1841) and draftsman Eduard Joseph d'Alton (1772-1840), Pander observed thousands of chicken eggs under a microscope, and ultimately discovered and described the chicken blastoderm and its structures, including the epiblast. [1]