The mesoderm is one of the three germ layers in the early developing embryo, the other two layers being the ectoderm and the endoderm. The mesoderm gives rise to tissues including connective tissue, muscles, and the circulatory system. The mesoderm is also believed to be responsible for the formation of the central nervous system. For example, the notochord is responsible for releasing certain factors which induce the ectoderm to become neural tissue. A germ layer is a layer of cells during fetal development that all have similar fates. ... Embryos (and one tadpole) of the wrinkled frog (Rana rugosa). ... The ectoderm is outermost of the three germ layers of the developing embryo, the other two being the mesoderm and the endoderm. ... The endoderm is one of the three germ layers of the developing embryo, the other two being the ectoderm and the mesoderm. ... Biological tissue is a substance made up of cells that perform a similar function. ... Connective tissue is any type of biological tissue with an extensive extracellular matrix and often serves to support, bind together, and protect organs. ... A top-down view of skeletal muscle Muscle is a contractile form of tissue. ... It has been suggested that Circulation (physiology) be merged into this article or section. ... The Central Nervous System (CNS) represents the largest part of the Nervous System. ... The notochord is a flexible rod-shaped body found in embryos of all chordates. ... The nervous system of an animal coordinates the activity of the muscles, monitors the organs, constructs and processes input from the senses, and initiates actions. ...

In a developing vertebrate embryo, the mesoderm differentiates into these areas:

• The chordamesoderm lies along the central axis, under the neural tube, and gives rise to the notochordal process which later becomes the notochord.

• The paraxial mesoderm, at the sides of the neural tube, gives rise to the somites and head mesoderm. The somites form the vertebral column dermis and skeletal muscle, while the head mesoderm will develop into facial muscle and cartilage.

• The intermediate mesoderm, between the paraxial mesoderm and the lateral plate, develops into the part of the urogenital system (kidneys and gonads).

• The lateral plate mesoderm is found at the periphery of the embryo. It will, in turn, split into two layers, the somatic layer/mesoderm and the splanchnic layer/mesoderm. Enclosed between the two is a space called coelom. The somatic layer forms the future body wall, and the splanchnic layer forms the circulatory system and future gut wall.

Because the mesoderm can form different ways in relation to the developing embryo's ectoderm, this is used as a method of categorizing animals. They are catagorized as: Acoelomates, Pseudocoelomates, and Coelomates, respectively. The neural tube is the embryonal structure that gives rise to the brain and spinal cord. ... The notochord is a flexible rod-shaped body found in embryos of all chordates. ... In the developing vertebrate embryo, somites are masses of mesoderm distributed along the two sides of the neural tube and that will eventually become dermis, skeletal muscle and vertebrae. ... Kidneys viewed from behind with spine removed The kidneys are bean-shaped excretory organs in vertebrates. ... The gonad is the organ that makes gametes. ... A body cavity is an aspect of a number of basic animal body plans (phyla) that incorporate a central body cavity, known as a coelom. ... It has been suggested that Circulation (physiology) be merged into this article or section. ... The ectoderm is outermost of the three germ layers of the developing embryo, the other two being the mesoderm and the endoderm. ... Phyla Porifera (sponges) Ctenophora (comb jellies) Cnidaria Placozoa Subregnum Bilateria  Acoelomorpha  Orthonectida  Rhombozoa  Myxozoa  Superphylum Deuterostomia     Chordata (vertebrates, etc. ... Acoelomates consist of two modern phyla of worms -- the Platyhelminthes and Nemerteans. ... A pseudocoelomate is an animal like a roundworm or rotifer. ... Coelomates (Pronounced Seel-uh-mates) are animals with a true body cavity. ...