Stroma () is the part of a
tissue or
organ
Organ may refer to:
Biology
* Organ (biology), a part of an organism
Musical instruments
* Organ (music), a family of keyboard musical instruments characterized by sustained tone
** Electronic organ, an electronic keyboard instrument
** Hammond ...
with a structural or connective role. It is made up of all the parts without specific functions of the organ - for example, connective tissue, blood vessels, ducts, etc. The other part, the
parenchyma
Parenchyma () is the bulk of functional substance in an animal organ or structure such as a tumour. In zoology it is the name for the tissue that fills the interior of flatworms.
Etymology
The term ''parenchyma'' is New Latin from the word π ...
, consists of the cells that perform the function of the tissue or organ.
There are multiple ways of classifying tissues: one classification scheme is based on tissue functions and another analyzes their cellular components. Stromal tissue falls into the "functional" class that contributes to the body's support and movement.
The cells
The Cells is a 3-piece American rock band based in Chicago, currently made up of singer/guitarist Cory Hance, bassist Johnny Furman and drummer Mark Doyle.
The band was formed in 1998 by singer/guitarist Cory Hance and bassist Brede Hovland. Hovl ...
which make up stroma tissues serve as a matrix in which the other cells are embedded.
Stroma is made of various types of
stromal cells.
Examples of stroma include:
*
stroma of iris
*
stroma of cornea
*
stroma of ovary
* stroma of
thyroid gland
The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobe (anatomy), lobes. The lower two thirds of the lobes are connected by a thin band of Connective tissue, tissue cal ...
* stroma of
thymus
*
stroma of bone marrow
Bone marrow is a semi-solid tissue found within the spongy (also known as cancellous) portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production (or haematopoiesis). It is composed of hematopoietic ...
*
lymph node stromal cell
*
multipotent stromal cell (mesenchymal stem cell)
Structure
Stromal connective tissues are found in the stroma; this tissue belongs to the group connective tissue proper. The function of connective tissue proper is to secure the
parenchyma
Parenchyma () is the bulk of functional substance in an animal organ or structure such as a tumour. In zoology it is the name for the tissue that fills the interior of flatworms.
Etymology
The term ''parenchyma'' is New Latin from the word π ...
l tissue, including blood vessels and nerves of the stroma, and to construct organs and spread mechanical
tension to reduce localised stress. Stromal tissue is primarily made of
extracellular matrix containing connective tissue cells. Extracellular matrix is primarily composed of
ground substance - a porous, hydrated gel, made mainly from
proteoglycan
Proteoglycans are proteins that are heavily glycosylated. The basic proteoglycan unit consists of a "core protein" with one or more covalently attached glycosaminoglycan (GAG) chain(s). The point of attachment is a serine (Ser) residue to whic ...
aggregates - and connective tissue fibers. There are three types of fibers commonly found within the stroma:
collagen type I,
elastic, and
reticular (collagen type III) fibres.
Cells
*
Wandering cells - cells that migrate into the tissue from blood stream in response to a variety of stimuli; for example, immune system blood cells causing inflammatory response.
* Fixed cells - cells that are permanent inhabitants of the tissue.
*
Fibroblast
A fibroblast is a type of cell (biology), biological cell that synthesizes the extracellular matrix and collagen, produces the structural framework (Stroma (tissue), stroma) for animal Tissue (biology), tissues, and plays a critical role in wound ...
- produce and secrete the organic parts of the ground substance and extracellular fibers of the matrix.
Types
# Loose connective tissue - This type is mainly located under the
epithelial membranes and glandular epithelium, attaching the epithelia to other tissues. It supports the blood vessels and nerves supplied to the epithelia. Additionally, it serves as the main site of
inflammatory response within the body.
# Dense irregular connective tissue - the function of this type is binding at a
high tensile strength between tissues to convert tension from one point.
References
External links
{{Authority control
Tissues (biology)