Anatomy & Organs

Ectoderm – structure, function & diseases

Ectoderm

The term ectoderm , which is derived from the Greek ektos meaning outside and derma, the skin , denotes the first upper germ layer. In the course of development, it forms the nervous system as well as the skin in humans and also in the animal world.

What is the ectoderm?

During what is known as gastrulation, which is an essential part of development, the blastula, which consists of a single cell layer, becomes a structure composed of three different cell layers.

The blastula is the egg cell after fertilization by a sperm and after multiple cell divisions. These three layers of cells that make up the blastula after gastrulation are referred to as the ectoderm, the outer layer of cells, the mesoderm , the inner layer of cells, and the endoderm, the inner layer of cells. The ectoderm forms the nervous system , sensory organs, skin , and teeth later in development .

The mesoderm develops into the muscle tissue, skeleton , blood vessels , and connective tissue. On the other hand, after the development of the embryo is complete, the endoderm forms the epithelium, the liver , the pancreas , and the respiratory and digestive systems. These three cell layers are also known as germ layers and are the basis from which the organs of humans and animals develop.

Anatomy & Structure

The germ layers each consist of a layer of cells. However, the cells of the germ layers, including those of the ectoderm, are not yet specialized. They are programmed to develop into a specific cell type. This is described as differentiation.This differentiation is controlled. Each cell contains the information as to which type of cell it should develop into. The cells of the different germ layers therefore have different information for differentiation. Even within a germ layer, the cells have different information about differentiation. Therefore, different cell types form from each cotyledon.

Like the ectoderm which forms the nervous system, but also the teeth. The cells of the germ layers are therefore determined, they have a predetermined differentiation path. However, it is possible for cells of one germ layer to become cells of another germ layer. This occurs during the formation of the mesoderm. This is then called transdetermination of the cell. It changes its original determination.

Function & Tasks

Animals and thus also humans, which form the three germ layers, are referred to as bilaterally symmetrical animals. The blastula, or blastocyst in humans sore in higher mammals, is a type of hollow sphere made up of a layer of cells. It first develops into the gastrula.

The two primary cotyledons are formed during this process. These are the outer ectoderm and the inner endoderm. At this stage of development, the endoderm forms the primordial mouth and the so-called primordial intestine. The mesoderm is formed slightly later. The cells rearrange during gastrulation. The cavity inside the sphere is filled more and more while the ectoderm completely closes the outside of the gastrula. Gastrulation then transitions into neurulation. This is the formation of the neural tube. The neural tube later forms the central nervous system , when the developmental process is complete.

The neural tube forms by remodeling of the neuroectoderm. This forms from the ectoderm and then forms the neural tube by folding the cell layer. First, the ectoderm thickens, which is induced by specific signals from the mesoderm. The neural plate forms. The edges of these plates form the neural ridges and form the neural groove between them. These neural ridges and the neural groove then form the neural fold, which eventually closes to form the neural tube. The front portion of the neural tube forms towards the brain and the tube behind then forms the spinal cord .

The cavity of the neural tube fills with cerebrospinal fluid. In addition, the eye sacs form in the front area, which later become the actual eyes. This process is referred to as the primary neurulation. Secondary neurulation, on the other hand, is the formation of fluid-filled cavities in the areas that connect to the neural tube.

Diseases

Spina bifida is the malformation of the neural tube. This malformation can be expressed in different ways. It occurs between the 22nd and 28th day of embryo development. During this time, neurulation takes place, which is the formation of the neural tube by the neuroectoderm.Spina bifida refers to the defective closure or non-closure of the neural tube at the back of the neural tube. Spina bifida manifests itself in different forms. Spina bifida occulta is characterized by the absence of the membranes of the spinal cord , the meninges. This form of spina bifida is not externally recognizable. This form is not serious and does not require treatment. Spina bifida aperta, on the other hand, is characterized by an incompletely closed neural tube. There are three forms of open spina bifida. Meningocele is a mild form of this condition.

The spinal cord membranes bulge out and form cysts under the skin, which can be surgically removed. The spinal cord is not affected. Meningomyelocele is a severe form of spina bifida. The spine has one or more breaks that allow portions of the spinal cord to protrude from the spine. Nerve damage occurs . However, this can be treated surgically. Myeloschisis is when nerve tissue is completely exposed. This is the most severe case of spina bifida aperta.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.