What is the notochord in zebrafish?
The notochord is critical for the normal development of vertebrate embryos. It serves both as the major skeletal element of the embryo and as a signaling source for the establishment of pattern within the neurectoderm, the paraxial mesoderm and other tissues.
Do fish embryos have a notochord?
In both fishes and amphibians, BMP proteins made in the ventral and lateral regions of the embryo would normally cause the ectoderm to become epidermis. The notochord of both fishes and amphibians secretes factors that block this induction and thereby allow the ectoderm to become neural.
When did fish develop a notochord?
around 530 Ma
The first ancestors of fish, or animals that were probably closely related to fish, were Pikaia, Haikouichthys and Myllokunmingia. These three genera all appeared around 530 Ma. Pikaia had a primitive notochord, a structure that could have developed into a vertebral column later.
What is notochord in fish?
notochord (English) A cartilaginous rod in the embryo that runs from head to tail and supports the nerve cord (cells which lie above the gut and below the nerve cord); in most fishes the notochord is replaced in the larval stage by the developing vertebrae, occupying anterior and posterior cavities, but in some …
Does fish have a notochord?
Did you know that fish, amphibians, reptiles, birds, and mammals are all related? They are all chordates. Chordates are a group of animals that includes vertebrates, as well as several closely related invertebrates. Chordates (phylum Chordata) are named after a feature they all share, a notochord.
Where is the notochord found?
The notochord is oriented head to tail and is found between the digestive tube and the nerve cord. Since it is composed of stiffer tissue, it allows for skeletal support of the organism. In certain chordates, like the lamprey and the sturgeon, the notochord remains there for life.
Do fishes notochord?
Accordingly, the notochord serves as the axial skeleton of the embryo until other elements, such as the vertebrae, form. In some vertebrate clades, such as the agnathans (lampreys), and in primitive fish, such as sturgeons, the notochord persists throughout life.
How does the zebrafish develop from one cell to the many cells that make up the larva?
Zebrafish develop rapidly from a one-cell zygote that sits on top of a large yolk cell. Gastrulation begins approximately 6 h post fertilization, hatching at 2 days as a free-swimming larvae. Zebrafish reach sexual maturity around 3 months of age and can live for up to 5 years.
What is the embryonic shield in zebrafish?
The appearance of the embryonic shield, a slight thickening at the leading edge of the blastoderm during the formation of the germ ring, is one of the first signs of dorsoventral polarity in the zebrafish embryo.
Where is the notochord?
The notochord lies along the anteroposterior axis (front to back), is usually closer to the dorsal than the ventral surface of the embryo, and is composed of cells derived from the mesoderm.
Is notochord necessary for slow muscle differentiation in fish?
Therefore, ntlmutant fish demonstrate that although mature notochord is not necessary for slow muscle formation, severe defects in notochord establishment in the tail correlate with loss of slow muscle differentiation. Shh induces ectopic slow muscle differentiation
What is the function of the somite in the zebrafish?
In the zebrafish, the somite gives rise mainly to muscle, which is probably the primary fate of paraxial mesoderm during early chordate evolution (Holland et al. 1995). Even in this simple system, however, three muscle cell populations can be resolved.
Does Shh induce muscle differentiation in zebrafish embryos?
In 15-somite zebrafish embryos, Shh induces a wide region of ectopic lateral differentiated muscle within the somite (46/53 unselected injected embryos, Fig. Fig.4G,H).4G,H). Ectopic slow muscle differentiation occurred without premature induction of fast muscle tissue (Fig. (Fig.4D–F).4D–F).
How many Mef2 genes are in zebrafish?
Three zebrafish MEF2 genes delineate somitic and cardiac muscle development in wild-type and mutant embryos. Mech Dev. 1996;59:205–218.