Mesenchyme, or mesenchymal connective tissue, is a type of undifferentiated loose connective tissue

Loose connective tissue

Loose connective tissue is extremely loose. It is a category of connective tissue which includes areolar tissue, reticular tissue, and adipose tissue....

 that is derived mostly from mesoderm

Mesoderm

In all bilaterian animals, the mesoderm is one of the three primary germ cell layers in the very early embryo. The other two layers are the ectoderm and endoderm , with the mesoderm as the middle layer between them.The mesoderm forms mesenchyme , mesothelium, non-epithelial blood corpuscles and...

, although some are derived from other germ layer

Germ layer

A germ layer, occasionally referred to as a germinal epithelium, is a group of cells, formed during animal embryogenesis. Germ layers are particularly pronounced in the vertebrates; however, all animals more complex than sponges produce two or three primary tissue layers...

s; e.g. some mesenchyme is derived from neural crest cells and thus originates from the ectoderm

Ectoderm

The "ectoderm" is one of the three primary germ cell layers in the very early embryo. The other two layers are the mesoderm and endoderm , with the ectoderm as the most exterior layer...

. In fact, most embryologists use the term mesenchyme only for those cells that develop from the mesoderm. The term mesenchyme essentially refers to the morphology of embryonic cells. Mesenchymal cells can migrate easily, unlike epithelial cells, which do not show great mobility and which are polygonal in shape, polarized in an apical-basal orientation, and organized into closely adherent sheets. Mesenchyme is characterized morphologically by a prominent ground substance

Ground substance

Ground substance is a term for the non-cellular components of extracellular matrix which contain the fibers.It is usually not visible on slides, because it is removed during the preparation process....

 matrix

Matrix (biology)

In biology, matrix is the material between animal or plant cells, in which more specialized structures are embedded, and a specific part of the mitochondrion that is the site of oxidation of organic molecules. The internal structure of connective tissues is an extracellular matrix...

 containing a loose aggregate of reticular fibrils

Reticular fiber

Reticular fibers or reticulin is a histological term used to describe a type of fiber in connective tissue composed of type III collagen. Reticular fibers crosslink to form a fine meshwork...

 and unspecialized cells. The cells are capable of developing into connective tissue

Connective tissue

"Connective tissue" is a fibrous tissue. It is one of the four traditional classes of tissues . Connective Tissue is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of...

, such as bone

Intramembranous ossification

Intramembranous ossification is one of the two essential processes during fetal development of the mammalian skeletal system by which bone tissue is created. Unlike endochondral ossification, which is the other process by which bone tissue is created, cartilage is not present during intramembranous...

, and cartilage

Cartilage

Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...

, the lymphatic system

Lymphatic system

The lymphoid system is the part of the immune system comprising a network of conduits called lymphatic vessels that carry a clear fluid called lymph unidirectionally toward the heart. Lymphoid tissue is found in many organs, particularly the lymph nodes, and in the lymphoid follicles associated...

, and the circulatory system

Circulatory system

The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...

.

See also

• Ectomesenchyme
  Ectomesenchyme
  Ectomesenchyme has similar properties to mesenchyme. The major difference is that ectomesenchyme is usually considered to arise from neural crest cells, which are a critical group of cells that form in the cranial region during early vertebrate development...
  
  
• Splanchnopleuric mesenchyme
• Somatopleuric mesenchyme
• Intramembranous ossification
  Intramembranous ossification
  Intramembranous ossification is one of the two essential processes during fetal development of the mammalian skeletal system by which bone tissue is created. Unlike endochondral ossification, which is the other process by which bone tissue is created, cartilage is not present during intramembranous...
  
  
• Mesenchymal stem cell
  Mesenchymal stem cell
  Mesenchymal stem cells, or MSCs, are multipotent stem cells that can differentiate into a variety of cell types, including: osteoblasts , chondrocytes and adipocytes...
  
  
• Mesoderm
  Mesoderm
  In all bilaterian animals, the mesoderm is one of the three primary germ cell layers in the very early embryo. The other two layers are the ectoderm and endoderm , with the mesoderm as the middle layer between them.The mesoderm forms mesenchyme , mesothelium, non-epithelial blood corpuscles and...
  
  
• Mesohyl
  Mesohyl
  The mesohyl, formerly known as mesenchyme, is the gelatinous matrix within a sponge. It fills the space between the external pinacoderm and the internal choanoderm...
  
  , the gelatinous matrix in sponges, was formerly also called mesenchyme.

External links

• Overview at University of Edinburgh
  University of Edinburgh
  The University of Edinburgh, founded in 1583, is a public research university located in Edinburgh, the capital of Scotland, and a UNESCO World Heritage Site. The university is deeply embedded in the fabric of the city, with many of the buildings in the historic Old Town belonging to the university...