Difference Between Mesoderm and Mesenchyme

The key difference between mesoderm and mesenchyme is that mesoderm is one of the three germ layers of bilaterally symmetrical animals while mesenchyme is an undifferentiated tissue found in embryonic true mesoderm.

In diploblastic animals, the body plan is relatively simple with two layers of cells. The two layers are the outer ectoderm and the inner endoderm. The ectoderm cells face the environment, and the endoderm cells face the enteron, which is a cavity with a single opening to the outside. The opening is the mouth. Moreover, triploblastic condition is the condition in which a third layer known as the mesoderm is developed in the embryo. Mesoderm lies between the ectoderm and the endoderm, separating the two layers of cells. The third layer is important to the body. In certain animals, much of the mesoderm remains undifferentiated and forms a packing tissue known as the mesenchyme, which supports and protects the organs of the body.

CONTENTS

1. Overview and Key Difference
2. What is Mesoderm 
3. What is Mesenchyme
4. Similarities Between Mesoderm and Mesenchyme
5. Side by Side Comparison – Mesoderm vs Mesenchyme in Tabular Form
6. Summary

What is Mesoderm?

Mesoderm is a layer of cells that separates ectoderm and endoderm of triploblastic organisms. Mesoderm helps triploblastic animals to grow in size. Moreover, it helps to separate the alimentary canal from the body wall. Not only that, mesoderm aids in forming a variety of organs. Organs combine to form an organ system. Some examples of these organ systems include the central nervous system, digestive system, excretory system, reproductive system, etc.

In addition, mesoderm also helps to improve the muscular activity of triploblastic organisms. Furthermore, it is necessary for their locomotion as ciliary or flagellar movements are not enough for locomotion. Although there are many advantages due to the evolution of the mesoderm, there are certain disadvantages as well. Mesoderm becomes a barrier to the transport of material between the ectodermal layers and the endodermal layers. In some animals, mesoderm completely fills the space between the ectoderm and the endoderm and this condition is called acoelomate.

What is Mesenchyme?

Mesenchyme, also called mesenchymal connective tissue, is a type of undifferentiated loose connective tissue. Most mesenchyme tissues originate from the mesoderm. But some may be derived from other germ layers such as ectoderm since they are derived from the neural crest cells. Hence, the term mesenchyme is most often used only for the cells developed from the mesoderm.

Mesenchymal cells have the ability to migrate easily whereas epithelial cells do not show much mobility. These are polygonal shaped cells with polarized apical-basal orientation. Mesenchyme possesses a prominent ground substance matrix containing a loose aggregate of reticular fibrils and unspecialized cells. These cells have the ability to develop into connective tissues such as bone, cartilage, the lymphatic system, and the circulatory system when required.

What are the Similarities Between Mesoderm and Mesenchyme?

• Mesenchyme has a mesodermal origin. In other words, the mesoderm forms mesenchyme.
• Both give rise to different types of connective tissues in the animal body.
• Bsides, both contain undifferentiated cells.

What is the Difference Between Mesoderm and Mesenchyme?

Mesoderm is one of the three germ layers of bilaterally symmetrical animals while mesenchyme is an undifferentiated tissue found in embryonic true mesoderm. So, this is the key difference between mesoderm and mesenchyme. Furthermore, mesoderm differentiates into the central nervous system, digestive system, excretory system, reproductive system, etc., while mesenchyme develops into connective tissues such as bone, cartilage, lymphatic system and circulatory system.

Generally, mesoderm appears only during the embryonic stage. But mesenchyme appears at every stage of animal life. Hence, this is also a difference between mesoderm and mesenchyme.

Summary – Mesoderm vs Mesenchyme

Mesoderm is one of the three germ layers of the early embryo. It is the middle layer containing masses of cells. Moreover, bilaterally symmetrical animals have three germ layers including the mesoderm. Mesoderm forms most of the central structures of the animal body including the skeletal system, muscular system, reproductive system, excretory system, circulatory system, etc. On the other hand, mesenchyme is an embryonic connective tissue that can give rise to all types of connective tissues in the body. Furthermore, it originates from the mesoderm. In fact, it is the undifferentiated tissue present in embryonic true mesoderm. Thus, this summarizes the difference between mesoderm and mesenchyme.

Reference:

1. “Mesoderm – Definition, Formation, Function and Quiz.” Biology Dictionary, 13 June 2017, Available here.
2. “Mesenchyme.” Wikipedia, Wikimedia Foundation, 4 May 2019, Available here.

Image Courtesy:

1. “Image from page 42 of “Elementary text-book of zoology [electronic resource]” (1901)” By Internet Archive Book Images (No known copyright restrictions) via Flickr
2. “Mesenchyme” By Jpogi at Wikipedia – Transferred from en.wikipedia to Commons by FastilyClone using MTC!., (Public Domain) via Commons Wikimedia