Thus, these epithelia do not need to keratinize to avoid desiccation. The lubrication provided by mucus helps to protect against abrasion.
Characteristic connective tissue cell types include both resident cells and immigrant or wandering cells.
Lab Exercise: Histology A Microscopic Study of Human Body Tissues and Mitotic Cells Introduction: Histology is the microscopic study of plant and animal tissues. Although all organisms are composed of at least Epithelial tissue, Connective Tissue, Muscle tissue and Nervous tissue. Bluetooth vs Wi-Fi Direct. Both Bluetooth and Wi-Fi are powerful wireless communication systems. Bluetooth is considered to be the better option when it comes to transferring data from one device to another, provided that these devices are close to each other, and when the data transfer speed is not essential. OVERVIEW of Connective Tissue. Connective tissue forms a framework upon which epithelial tissue rests and within which nerve tissue and muscle tissue are embedded.
Fibroblasts which secrete the fibers and ground substance of the extracellular matrix. Adipocytes which store fat. Macrophages which ingest and remove foreign material or damaged cells. Fibroblasts are responsible for secreting collagen and other elements of the extracellular matrix of connective tissue.
In microscopic appearance, fibroblasts lack obvious specialized features. And fibroblasts throughout the body all appear similar to one another, wherever they occur in ordinary connective tissues. There is thus little about fibroblasts to attract the attention of an observer.
However, fibroblasts are essential for normal development and repairand recent research PLoS Genetics has shown that fibroblasts from different regions display extensively differentiated patterns of gene expression which Histology tissues and epithelial tissue guide differentiated patterns of tissue organization, such as different types of skin and hair in different areas.
Indeed, the single cell type called "fibroblast" may properly represent many distinctly but invisibly different cell types, including "mesenchymal stem cells" which retain capacity to differentiate into other cell types see Science The name "fibroblast" is something of a misnomer, since most cells with "blast" in their name are embryonic precursor cells which subsequently differentiate into specialized cell types.
Fibroblasts are already a mature, differentiated cell type although some may have the capacity to differentiate into other mesenchymal cell types as well. Resting fibroblasts typically have so little cytoplasm that the cells commonly appear, by light microscopy, as "naked" nuclei.
Fibroblast nuclei appear dense heterochromatic and are usually flattened or spindle-shaped. The pink material in this thumbnail image is extracellular collagen. Fibroblasts are active during growth but are normally quiescent in the adult.
When active, fibroblasts are actively secretory, manufacturing the collagen and other components of the extracellular matrix of connective tissue. Active fibroblasts appear larger than resting ones, with more cytoplasm and with nuclei that are more euchromatic less densely stained.
Resting fibroblasts retain the ability to become active and to multiply when necessary, as during healing after injury. Scars are formed by fibroblast activity during tissue repair.
The substance of the scar is collagen deposited by fibroblasts to replace damaged tissue.
For an image of scar formation, see WebPath. For recent research on fibroblast involvement in scar formation, see Science Closely related to fibroblasts are the chondroblasts which produce the matrix of cartilage and the osteoblasts which produce the matrix of bone.
The appearance of "blast" in a cell name normally indicates an embryonic cell that transforms into a mature cell type e. However, in the case of "fibroblast", "chondroblast" and "osteoblast", this designation indicates a cell which secretes fibers, cartilage or bone. Adipocytes are large connective tissue cells which contain a substantial amount of lipid stored in the form of conspicuous round droplets.
Adipocytes function primarily as warehouses for reserve energy. En masse, they also assist in thermoregulation maintaining body temperature and in a few sites offer some cushioning capacity e. Since most loose connective tissue contains scattered clusters of adipocytes, the term adipose tissue is usually reserved for large masses grossly visible of these cells.Histology of tumor tissue remains the bedrock upon which diagnosis is established and is the basis for selecting appropriate testing to guide treatment.
Histologic diagnosis, although simple in concept, is extremely complex in practice and crucially depends on the expertise of the examining pathologist. Epithelium Study Guide. Epithelial tissue comprises one of the four basic tissue kaja-net.com others are connective tissue (support cells, immune cells, blood cells), muscle tissue (contractile cells), and nervous kaja-net.com represent various combinations of these four basic tissue types, which thus comprise the entire body.
This note covers the following topics: Basic Histological Techniques, Epithelial Components, Stratified Epithelia, Connective Tissue, Muscle Tissue, Nerve Tissue, Stains and Staining, Lymphoid Organs, Digestive System - Oral Cavity, Tract and Glands, Respiratory System, Endocrine System, Male Reproductive System and Female .
Now go to Histology Zoomer Home Page and try the Self-guided connective tissue library and the connective tissue quiz. Section V -- Nervous Tissue Return to Top Nervous tissue is composed of neurons and their supporting cells (glial cells or neuroglia).
Connective tissue consists of cells separated by varying amounts of extracellular substance. In connective tissues cells typically account for only a small fraction of the tissue volume.
Epithelia are tissues consisting of closely apposed cells without intervening intercellular substances. Epithelia are avascular, but all epithelia "grow" on an underlying layer of vascular connective tissue. The connective tissue and the epithelium are separated by a basement membrane.