Histology: Connective Tissue- Embryonic Connective Tissue Flashcards
What is the main embryonic tissue?
mesenchyme
Where is the mesenchyme primarily found?
in the embryo
What is the structure of the mesenchyme?
- small, spindle shaped cells
- uniform appearance
- processes extend from these cells and contract similar processes of neighbouring cells (forming a three-dimentional cellular network)
- the extracelular space is occupied by a viscous ground substance
What is the extracellular space of mesenchyme occupied by?
the extracelular space is occupied by a viscous ground substance
viscous- thickk consistency
What do spindle shaped cells create when they connect to each other by their ‘endings’?
a three-dimentional cellular network
Why are the mesenchyme cells an exception to connective tissue?
It does not have any fibers. (It is composed only of ground substance and mesenchyme cells).
What happens to mesenchymal cells as they develop?
Mesenchymal stem cells first proliferate and then differentiate into adult connective tissue cells.
eg.
osteoblasts
chondrocytes
adipocytes
fibroblasts
proliferate= multiply
What are the primary bone cells?
osteocytes (created through osteoblasts from mesenchymal stem cells)
What are the primary cartilage cells?
chondrocytes (created through transitory chondrocytes from mesenchymal stem cells)
What are the primary adipose tissue cells?
adipocytes (created through pre-adipocytes from mesenchymal stem cells)
What are the primary connective tissue proper cells?
Fibrocytes created through transitory fibroblasts.
What is another example of embryonic connective tissue?
Mucous connective tissue
Where is mucous connective tissue found?
in the umbillical chord
What does the mucous connective tissue consist of?
- specialized, almost gelatin like ECM,
- its ground substance is referred to as “Whartons Jelly”,
- spindle shaped cells
- widely seperated
- appear like fibroblasts in the near-term umbillical chord
What is the ground substance of mucous connective tissue cells referred to as?
Whartons Jelly
What are “Wharton’s jelly mesenchymal stem cells”?
Cells which are isolated from Whartons jelly, expressing significant amounts of mesenchymal stem cells and having the ability to differentiate under adequate condition into cells such as:
- osteocytes
- chondrocytes
- adipocytes
- neural-like cells
What is the difference between mucous and mesenchyme connective tissue?
The embryo or fetus is mostly filled with mesenchyme in all of its capacity.
The umbillical chord is filled with mucous connective tissue.
What can the Wharton Jelly do in particular cases eg. damage of mesenchymal cells)?
In some particular substances (such as damage or lack of mesenchymal cells) Wharton jelly can act in the same manner as mesenchymal cells (can support the mesenchyme).
What is the common precursor tissue of all connective tissues?
mesenchyme
How is the mesenchyme formed?
Cells migrating from the germimal layers in the embryonic body (from the mesoderm and ectoderm).
What type of nucleus do most mesenchyme cells have? What does this mean/allow for?
nucleus filled with euchromatin, indicating their high transcriptional activity.
What do mesenchyme cells produce?
the extracellular matrix
What do mesenchymal cells differentiate into?
individual types of connective tissue, cartilage, bone, hematopoietic and endothelial cells.
What property of mesenchymal cells decreases during their maturation?
- ability to produce the cellular matrix
- ability to undergo mitosis
What is the intermediary fillament of connective tissue called?
vimentin
