Pre-Lab Reading Introduction Connective tissue is a term used to describe the tissue of mesodermal origin that that forms a matrix beneath the epithelial layer and is a connecting or supporting framework for most of the organs of the body. This lab will focus on the so-called connective tissue proper and cartilage; the next lab will focus on bone.
In connective tissues cells typically account for only a small fraction of the tissue volume. The extracellular substance consists of fibres which are embedded in ground substance containing tissue fluid.
Fibres in connective tissue can be divided into three types: Extracellular Substance Collagen fibres Collagen fibres are the dominant fibre type in most connective tissues.
The primary function of collagen fibres is to add strength to the connective tissue. Longitudinal striations may be visible in thicker fibres. These striations reveal that the fibres are composed of thinner collagen fibrils 0.
Each of these fibrils is composed of microfibrils, which are only visible using electron microscopy. Microfibrils are assemblies of tropocollagen, which, in turn, is an spiral-like assembly of three collagen molecules triple helix.
The organisation of the tropocollagen within the microfibrils is highly regular. A small gap 60 nm wide is found between the subsequent tropocollagens which form the microfibrils.
Staining solutions used in electron microscopy tend to fill in these gaps, and the alignment of the gaps gives the microfibrils a cross-striated appearance with 68 nm intervals in EM images. Coarse collagen fibres are formed by type I tropocollagen.
There are many different tropocollagen types around currently named type I to XXI. These types differ in their content of the amino acids hydroxyproline and hydroxylysine.
They also differ in the amount of carbohydrates attached to the collagen molecules. The different types of tropocollagen give the fibres the structural and functional features which are appropriate for the organ in which the fibres are found.
Tropocollagen type IV is an important structural component of the basal lamina. Reticular fibres Reticular fibres are very delicate and form fine networks instead of thick bundles. They are usually not visible in histological sections but can be demonstrated by using special stains.
For example, in silver stained sections reticular fibres look like fine, black threads - coarse collagen fibres appear reddish brown in the same type of preparation.
Because of their different staining characteristics, reticular fibres were initially thought to be completely different from collagen fibres.
Cross-striations with the same periodicity as in coarse collagen fibres are however visible using electron microscopy. We now know that reticular fibres consist of collagen - although the main type of tropocollagen found in reticular fibres, type III, is different from that of the coarse collagen fibres.
Reticular fibres give support to individual cells, for example, in muscle and adipose tissue. They appear as fine black lines in this silver stained preparation.Histology, also microanatomy, is the branch of biology which studies the tissues of animals and plants using microscopy.
It is commonly studied using a light microscope or electron microscope, the specimen having been sectioned, stained, and mounted on a microscope kaja-net.comogical studies may be conducted using tissue culture, where live animal cells are isolated and maintained in an.
Histology is the study of tissues. A tissue, you may recall is a collection of cells that has a particular function. Histology and pathohistology (the study of disease processes in tissues) is rarely the allied health student's favorite unit in the course.
transitional epithelium. simple columnar epithelium. elastic cartilage. connective tissue. simple cuboidal epithelium. simple columnar epithelium. goblet cell.
stratified squamous epithelium. erythrocytes. leukocytes. Histology Lab Photo Quiz. terms. BIOL Axial Skeleton Bones and Bony Landmarks. 20 terms. Also, smooth muscle tissue is mostly cellular (and therefore more nuclei are present), whereas the connective tissue is mostly extracellular collagen fibers with fewer cells.
The table below compares the differences in the morphology of the three types of muscle. Dec 17, · Connective tissue is derived from the third germ layer, the mesoderm. This is the very same source from which muscle tissue is developed. The types of connective tissue include adipose, fibrous, and elastic tissue as well as blood, bone, and cartilage.
/5(6). Additional Resources. These links will open a new browser window. Large Images Search the Large Images page with these keywords: dense irregular connective tissue, dense regular connective tissue, reticular connective tissue, mesenchymal connective tissue, white adipose tissue, brown adipose tissue, macrophage, adipocyte, mast cell .