Embryology is the basis for understanding the intimate relationship between structures in different systems, such as the nervous and muscular systems, and is primordial to understanding the developmental disorders that in the human being can present as one of the congenital myopathies.

Embryonic development

The first stage of embryonic development begins with fertilization. This is the process of merging male sperm with female egg and is the basis of embryology covered in the article. After fertilization, there is the formation of the inner cell mass and the outer cell mass and the zygote eventually becomes a blastocyst which is then ready for implantation.

The inner cell mass of the embryo then undergoes a highly specialized transformation called gastrulation in which the bilaminar disc of the inner cell mass is displaced to become a trilaminar disc; Thus, forming the three germ layers that we know: ectoderm, mesoderm and endoderm.

The skin, which is derived from the ectoderm, is then innervated by the spinal nerves and a single area of skin innervated by a single spinal nerve; It is what we call a dermatome. Similarly, a group of muscles innervated by a single spinal nerve; It is called a myotome.

The cardiovascular system is one of the first systems to appear within embryological growth.

The development of the face, head and neck are closely linked to each other and depend on certain structures known as pharyngeal arches. These arches are of mesenchymal origin that together with the pediment prominence form the face.

The development of the reproductive and urinary systems is closely related since they share a common caudal end point known as the cloaca. Both systems derive from the intermediate mesoderm from the gonadal crest.

Finally, the respiratory system develops as a diverticulum from the esophagus and the primary intestinal tube. The formation of the tracoesophageal septum separates the two structures.

Katherine Johnson, M.D., is a board-certified obstetrician-gynecologist with clinical expertise in general obstetrics and gynecology, family planning, women’s health, and gynecology.

She is affiliated with the Obstetrics and Gynecology division at an undisclosed healthcare institution and the online platform, Maternicity.com.

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