Endoderm: births and development during pregnancy

The development and growth of the human body is an extremely complex and fascinating process in which the different structures work with millimeter precision to give rise to different organs and bodily systems.

One of these structures is the endoderm, A diaper or layer of fabric that we will talk about throughout this article. This layer is one of the oldest biological parts in terms of development and gives rise to important vital organs such as those found in the digestive system.

    What is the endoderm?

    Endoderm refers to the innermost layer of tissue of the three layers that develop during embryonic growth of animals. These strata called germ layers are the ectoderm, which is the outermost layer, and the mesoderm or middle layer.

    However, it should be noted that not all species have these three germ layers. According to each animal group, the embryonic cells can derive in two or three layers, respectively forming diblásticos and triblásticos beings. However, they all have the endoderm layer, which is under the rest.

    In the case of the endoderm, it appears around the third week of gestation, being considered one of the oldest layers in the process of embryonic differentiation. Outraged, it is from this layer of cells from which many vital organs are born for the survival of the living adult being.

    From this germ layer, most of the most important internal organs are formed. Some of them are the alveoli which are lodged in the lungs, the whole digestive tract as well as its secretory glands, the epithelium of certain glands such as the thyroid or the scam, and finally certain parts of the kidneys, the bladder and the ‘urethra.

      How is it evolving?

      During the early stages of embryonic development, the embryo is made up of a single layer of cells. It then folds into itself in a process called gastrulation, where the first layers of cells are born. The first of these layers to appear is that of the endoderm.

      Around the second week of gestation, a group of migrating cellular organisms glide towards the hypoblast cells, An internal mass formed by cubic cells, and becomes the final endodermal layer.

      The next phase in the development of the embryo is called organogenesis. This is responsible for producing the corresponding changes in the embryonic layers and gives way to the formation of appropriate organs and tissues.

      As noted above, in the case of the endoderm, this will give birth to different organs of the digestive and respiratory system, As well as in the epithelial envelope of certain parts of the body. However, it should be clarified that these organs are not definitive structures but primitive members which are not yet fully developed.

      Types of endoderm

      Due to the differentiation of the embryonic body, the endoderm is sectioned into two parts which have their own characteristics. These parts are the embryonic endoderm and the extraembryonic endoderm. These two divisions are connected by a large orifice which, later, it will become the umbilical cord.

      1. Embryonic endoderm

      The embryonic endoderm is the section of the endodermal layer that will give rise to the internal structures of the embryo, forming the primary intestine. In addition, this embryonic layer it works with the mesodermal layer to form the notochord. When this structure is fully developed, it is the main one responsible for emitting the signals necessary to make cell migration and differentiation possible; an extremely important process for allowing the formation of organic structures such as the brain.

      From there, the notochord and endoderm perform a parallel development in which the former generates a series of folds that will form the cranial, flow and lateral axes of the embryo; while the folds of the endoderm remain inside the body forming the intestinal tract.

      2. Extraembryonic endoderm

      The second division of the endoderm is that which remains outside the embryo formando the well-known yolk sac. This membranous appendix is ​​connected to the embryo, providing sufficient nutrients and oxygen, as well as the release of metabolic waste products.

      However, this division of the embryonic endoderm does not persist until the end of embryonic development but usually disappears around the tenth week of gestation.

      Sections of the intestinal tract

      In the previous section, it was mentioned that the embryonic endoderm gives rise to a structure called the intestinal tract. This structure can be differentiated as well into different sections which can correspond to the embryonic endoderm as well as to the extraembryonic endoderm. These sections are:

      1. Cranial intestine

      Known as the cranial or internal intestineThis structure is located inside the embryo’s skull. During the early stages of development in this way, the buccopharyngeal membrane, which gradually turns into the pharynx. The lower limit then forms a structure known as the airways.

      Finally, the intestinal tract it expands to become what ultimately corresponds to the stomach.

      2. Large intestine

      Located in the east fold the precursor of the allantoic membrane. Such an extra-embryonic which appears by the formation of folds located next to the yolk sac.

      3. Middle intestine

      Finally, the midgut is located between the cranial structures and the outlets. Its extension expands to reach the yolk sac through the umbilical cord. Thanks to him, the embryo receives enough nutrients from the mother’s body and allow its proper development.

      What organs does it transform into?

      It has already been mentioned several times that the endoderm is the primitive structure through which a large part of the organs and body structures arise, a process called organogenesisIn other words, the birth of organs.

      This process of final organ development usually takes place between calves and the eighth week of care. However, it was found that in people identifiable organs can be identified from the fifth week.

      To be more precise, of the endodermal layer derive these structures:

      • Viteline bag.
      • Allantois.
      • respiratory tracts, Specifically the bronchi and pulmonary alveoli.
      • Epithelium and connective tissue of tonsils, pharynx, larynx and trachea. As well as the epithelium of the lungs and parts of the gastrointestinal tract.
      • Bladder.
      • Eustachian tube epithelium, ear cavities, thyroid and parathyroid glands, scam, vagina and urethra.
      • Glands of the digestive system, Specifically from the gastrointestinal tract; as well as the liver, gallbladder and pancreas.

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