What Is the Mesoderm?

Mesoderm refers to the layer of cells between the ectoderm and endoderm (end-gut embryonic stage) during the embryonic development of trigerminal animals. Including axonal mesoderm (spine); parachondral mesoderm (sarcoma; osteosynthesis, sarcomere, dermatoderm); interstitial mesoderm (urinary system, reproductive system); lateral mesoderm (wall layer, visceral layer). Mesoderm develops into the body's dermis, muscles, bones, and other connective tissues and circulatory systems, including the heart, blood vessels, bone marrow, lymph nodes, lymphatic vessels, etc .; the end of the body cavity, the serosa and mesentery of the internal organs, and the connective tissues and blood vessels in the internal organs And smooth muscle; kidney, urethra, gonads (excluding germ cells), genital ducts, and cortex of adrenal glands.

Mesoderm

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Mesoderm refers to the

On the 15th to 16th days of human embryo development, ectodermal cells migrate to the midline to form primitive streaks. Primitive primitive streak cells proliferate and spread into a layer between the ectoderm and endoderm.

Starting from flat animals, mesoderm appeared between the ectoderm and the endoderm.

The appearance of mesoderm is of great significance to the further development of animal body structure and function.

On the one hand, the formation of mesoderm reduces the burden on the endoderm and ectoderm, causing a series of tissue, organ, and system differentiation, providing the necessary material conditions for the further complexity and completeness of the animal's body structure, so that flat animals reach the organ system Level.

On the other hand, the formation of mesoderm promotes the strengthening of metabolism. For example, a complex muscle layer is formed from the mesoderm, which enhances motor function, plus a symmetrical body shape. It makes it possible for animals to consume more food on a larger scale. At the same time, due to the muscles on the digestive tract wall, the ability of the digestive tract to move is also strengthened. These undoubtedly promote the strengthening of the metabolic function. Due to the strengthening of the metabolic function, the metabolic waste generated also increases, thus promoting the excretion system form.

Flat animals began to have a primitive excretory system-the protorenal duct. In addition, due to the improvement of the animal's motor function, frequent exposure to the changing external environment has promoted the further development of the nervous system and sensory organs. The nervous system of flat animals has improved significantly compared to coelenterate animals, and has begun to focus on the ladder-type nervous system.

In addition, the parenchyma formed by the mesoderm has the function of storing nutrients and water. Animals can endure hunger and drought to some extent. Therefore, the formation of mesoderm is also one of the basic conditions for animals to evolve from aquatic to terrestrial.