Difference Between Mesenchyme and Mesoderm

Main Difference – Mesenchyme vs Mesoderm

Mesenchyme and mesoderm are two types of unspecialized cells which occur during gastrulation. Gastrulation is the process in which the three primary germ layers, endoderm, mesoderm, and ectoderm develop during the embryonic development of an animal. The mesoderm only appears in the embryonic development, but the mesenchyme is found throughout the life of an animal. Mesenchyme gives rise to several pathological conditions as well. The main difference between mesenchyme and mesoderm is that mesenchyme is a part of mesoderm of an embryo which develops into connective tissue, cartilage, bone, etc. whereas mesoderm is one of the three germ layers in the embryo of a metazoan animal and through the embryonic development, mesoderm produces the internal organs of the adult.

Key Areas Covered

1. What is Mesenchyme 
      – Definition, Structure, Formation, Role
2. What is Mesoderm
      – Definition, Structure, Formation, Role
3. What is the difference between Mesenchyme and Mesoderm
      – Comparison of Key Differences

Key Terms: Mesenchyme, Mesoderm, Gastrulation, Embryonic Development, Endoderm, Ectoderm, Germ Layers, Ingression

What is Mesenchyme

Mesenchyme is a type of animal tissue that is comprised of loose cells embedded in an extracellular matrix with a mesh of proteins and fluids. The loose, fluid nature of the mesenchyme tissue allows it to migrate between germ layers during embryonic and fetus development. Mesenchyme gives rise to connective tissues, bones, cartilage, lymphatic, and cardiovascular systems. A major part of the mesenchyme is derived from the mesoderm while a small part is derived from the ectoderm. The neural crest is specialized from the mesenchyme, which is derived from the ectoderm. During gastrulation, the epithelial-mesenchymal transition (EMT) gives rise to the mesodermal layer of the embryo. The EMT plays a major role in cellular proliferation and tissue repair in the body even after the embryonic development. The EMT causes many pathological processes, including fibrosis, which is the development of excess fibrous connective tissue and metastasis, which is the spread of disease between organs in the body. The transition between mesenchyme and epithelial tissues helps the formation of organs in the body as well. In contrast, mesenchymal stem cells found in small quantities in fat, bone marrow, muscles, baby teeth, and dental pulp are fixed cells.

Figure 1: Mesenchyme

What is Mesoderm

Mesoderm is the middle of the three germ layers. Hence, mesoderm is located between ectoderm and endoderm. The mesoderm gives rise to muscle, bone, cartilage, connective tissues, bone marrow, blood, lymphatic vessels, body cavities, and organs like kidney, uterus, and gonads. During gastrulation, the waves of epiblast cells migrate through the primitive streak in the process called ingression. During the first wave of migrating cells, EMT occurs, displacing the hypoblast cells and becoming the endoderm. The second wave of migrating epiblast cells populate on the endoderm, forming the mesoderm layer. The mesoderm layer gives rise to paraxial mesoderm, intermediate mesoderm, lateral plate mesoderm, cardiogenic mesoderm, and notochondrial midline tube. Once the mesoderm is formed, the rest of the epiblast cells ingress to form the ectoderm. The mesoderm in the embryo is shown in figure 2.

Figure 2: Section of a mesoderm

Difference Between Mesenchyme and Mesoderm

Definition

Mesenchyme: Mesenchyme is a part of the mesoderm of an embryo which develops into connective tissue, cartilage, bone, etc.

Mesoderm: Mesoderm is one of the three germ layers in the embryo of a metazoan animal.

Location

Mesenchyme: Mesenchyme is located in the mesoderm.

Mesoderm: Mesoderm is located in between ectoderm and endoderm.

Differentiation

Mesenchyme: Connective tissue, blood vessels, lymphatic vessels, cartilage, and bone, are derived from the mesenchyme.

Mesoderm: Connective tissue, bone, cartilage, muscle, blood and blood vessels, lymphoid organs and lymphatics, pericardium, notochord, pleura, kidney, and gonads are derived from the mesoderm.

Appearance

Mesenchyme: Mesenchyme appears at every stage of animal life.

Mesoderm: Mesoderm appears only in the embryonic development.

Conclusion

Mesenchyme and mesoderm are two unspecialized cell types found in animals. Mesoderm is one of the three primary germ layers of the embryo. It gives rise to connective tissue, bone, cartilage, muscle, blood and blood vessels, lymphoid organs and lymphatics, and organs in the body. Mesenchyme appears in the body even after the embryonic development and plays a key role in cellular proliferation and tissue repair in the body. Fibrosis and metastasis like pathological conditions may arise due to the defects in the mesenchyme. The main difference between mesenchyme and mesoderm is in their function in the body.

Reference:

1. “The Embryo Project Encyclopedia.” Mesenchyme | The Embryo Project Encyclopedia. N.p., n.d. Web. Available here. 02 June 2017. 
2. “Mesoderm.” Encyclopædia Britannica. N.p., n.d. Web. Available here. 02 June 2017. 
3. “Mesoderm – Development and Stem Cells.” LifeMap Discovery®. N.p., n.d. Web. Available here. 02 June 2017. 
4. “Mesoderm vs Mesenchyme – What’s the difference?” WikiDiff. N.p., 01 June 2017. Web. Available here. 02 June 2017.

Image Courtesy:

1. “Mesenchyme” By Jpogi at Wikipedia – (Public Domain) via Commons Wikimedia 
2. “Gray21” By Henry Vandyke Carter – Henry Gray (1918) Anatomy of the Human Body (Public Domain) via Commons Wikimedia