Thursday, June 11, 2015

The Three Primary Germ Layers


What do the primary germ layers give rise to?


Germ layer is a primary layer of cells that form during embryogenesis, each layer will eventually give rise to systems, tissues and organs as the embryo grows.

Ectoderm is the outer most layer and gives rise to the integument including hair, nails and epidermis, and the epithelial of the nose, mouth and the sense of the eye, the nervous system and inner ear)

Mesoderm is the middle layer and it forms the musculoskeletal, circulatory and most of the excretory systems. Mesoderm also develops into  gonads and the muscular and connective tissue in the digestive and respiratory system

Endoderm is the inner layer, which will eventually develop into the epithelia linings of the digestive and respiratory tracts including the lungs. It also forms the pancreas, thyroid, bladder and distal urinary tracts. Finally it will also form parts of the liver as well.

Mnemonics:


  • Ectoderm - "attracto" derm (things that attract us to others, such as cosmetic features and "intelligence")
  • Mesoderm - "means" oderm (the means of getting around as an organism, such as bones and muscle; the means of getting around in the body, such as the circulatory system; the means of really getting around, such as the gonads)
  • Endoderm - linings of "endernal" organs (the digestive and respiratory tract, and accessory organs attached to these systems)


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