The Zebrafish Model

In this practical, the teleostic model of Zebrafish, also called Danio rerio, was examined in its various stages of neurulation. The Zebrafish model is beneficial to experiments like this one for a number of reasons, the most major one in this experiment being its short life cycle. The life cycle of a Zebrafish is extremely short, lasting only 90 days. This fact is important as in the practical that was carried out, the majority of the neurulation of the Zebrafish can be observed in a number of hours as within the first 24 hours after fertilisation, the formation of the zygote, cleavage, blastulation, gastrulation and segmentation can each be observed. The size of the Zebrafish embryo is important as well, as the large diameter of 0.7mm egg,
The zebrafish shares roughly 70% of its genes with humans, which makes zebrafish an important tool in the discovery of the pathways of diseases, as well as the discovery of genes associated with diseases. The neural circuitary in the brain is an important feature in the development of humans, and in zebrafish, this can be intricately examined, specifically in the case of locomotion. When touch evoked response is initiated, similarly to humans it can be altered, and as the neural circuit is more simple in zebrafish, it provides with an important research tool to the study of human locomotive diseases. [2] Zebrafish experimentation is also cheap, the Zebrafish produces hundreds of eggs at a time, as well as year round, and they require very little maintenance, so these experiments can be done quickly and easily too.
A maternal to zygotic gene expression occurs due to the blastomeres receiving their mRNA from oocytes. The cell gene length begins to increase due to the gap phases increasing in length. The entire cell becomes more rounded, as the blastomeres begin to pile on top of each other. There is no clear plane for cleavage at this stage. In this phase, the embryo will arrive in midblastula transition phase. The plane of cleavage is no longer able to be identified, and no blastocoel is available. The Yolk Syncytial Layer (YSL), by the blastodisc interaction with the yolk, is formed around the 512-cell stage. When Squint, a nodal factor, is expressed due to high concentrations of β-catenin in the nuclei, the cells begin to associate with each other. This forms a fate prediction in the later stages of the blastula. After YSL begins to get larger, the cell begins to undergo epiboly which causes blastomeres closest to the margin to exhibit proteins like Squint, which, due to its ability to alter nodal concentrations, can aid in cell determination. The low concentrations of nodal induce the notochord formation, whereas higher concentrations induce prechordal plate formation.