User:Rbpalomino/sandbox

Article evaluation
I read the Epimorphosis article and I think it needs a lot of work. I think that for a person who does not know much about Biology it might confusing. Besides, it does not give much information about. It talks about the phenomena that happen in nature and only cites one example.

Invagination
In developmental biology, Invagination is a mechanism that takes place during gastrulation. This mechanism or cell movement happens mostly in the vegetal pole. The invagination consists of the folding of an area of the exterior sheet of cells towards the inside of the blastula. In each organism, the complexity will be different depending on the number of cells. Invagination can be referenced as one of the steps of the establishment of the body plan. The term, originally used in embryology, has been adopted in other disciplines as well. It has many meanings in each term or subject.

Tunicates
In tunicates, Invagination is the first mechanism that takes place during gastrulation. The four largest endoderm cells are the ones that induce the invagination process in the tunicates.The invagination consists of the internal movements of a sheet of cells (the endoderm) based on the changed in their shape. The blastula of the tunicates is a little flattened in the vegetal pole making a change of shape from a columnar to a wedge shape. Once the endoderm cells were invaginated, the cells will keep moving beneath the ectoderm. Later, the blastopore will be formed and with this, the invagination process will be finished. The blastopore will be bordered by the mesoderm by all sides.



Amphioxus
The invagination in Amphioxus is the first cell movement of gastrulation. This process was first described by Conklin. During gastrulation, the blastula will be transformed by the invagination. The endoderm will fold towards the inner part and that way the blastocoel will be gone transforming into like a cup-shaped structure with a double wall. The inner wall will be called the archenteron; which is the primitive gut. The archenteron will open to the exterior through the blastopore. The outer wall will become the ectoderm. Later forming the epidermis and neural crest.