Pdf classification of tissues

In consideration of their distinct clinicopathologic features, undifferentiated round cell sarcomas are now kept separate from Ewing sarcoma and subclassified, according to the underlying gene rearrangements, into three main subgroups CIC, BCLR and not ETS fused sarcomas Importantly, In order to avoid potential confusion, tumour entities such as gastrointestinal stroma tumours are addressed homogenously across the different WHO fascicles.

Pathologic diagnosis represents the integration of morphologic, immunohistochemical and molecular characteristics and is a key element of clinical decision making. The WHO classification is as a key instrument to promote multidisciplinarity, stimulating pathologists, geneticists and clinicians to join efforts aimed to translate novel pathologic findings into more effective treatments. Keywords: WHO classification; molecular genetics; morphology; new entity; soft tissue sarcoma. Abstract Mesenchymal tumours represent one of the most challenging field of diagnostic pathology and refinement of classification schemes plays a key role in improving the quality of pathologic diagnosis and, as a consequence, of therapeutic options.

Publication types Review. Substances Biomarkers, Tumor. Due to the bushy appearance that they sometimes produce, they are sometimes referred to as the brush border of an organ.

Obtain a slide of the lung. Using proper technique, mount the slide on the stage and locate the tissue. The lungs contain small air sacs called alveoli and these structures are composed of a single layer of flattened cells called simple squamous epithelium.

Notice that one surface is facing an open space to the inside of the air sac. This open space is referred to as the lumen used to refer to any space or opening inside an organ or structure and the cell surface facing it is the apical surface. For additional images, click HERE. Simple Cuboidal Epithelium: 1. Obtain a slide of the kidney. The kidney tubules are composed of simple columnar epithelium and will appear as thick-walled circlular structures scattered throughout the slide.

Again, notice the lumen in the center of each tubule and take note of the single layer of square cells surrounding it.

Simple Columnar Epithelium: 1. Obtain a slide of the intestine. Notice that the lining of the intestine is marked with finger-like projections hanging into the lumen. These structures are called villi and they act to increase the surface area of the intestine to encourage absorption. The tissue lining the inside of the organ is simple columnar epithelium. Notice the large rectangular cells.

You might also notice clear looking cells which are goblet cells. These cells produce mucus to lubricate and protect the lining of the intestine. Pseudostratified Columnar Epithelium: 1.

Obtain a slide of the trachea. The tissue lining the trachea is marked by the presence of goblet cells and is covered with tiny hair-like structures called cilia. The cilia act to trap debris and to distribute the mucus secreted by the goblet cells across the surface of the tissue.

Notice that the cells are irregularly shaped and that the nuclei of the cells are found in differing spots within the cells.

This is what gives the tissue its false layered appearance. If you examine the tissue closely, you will see that a single cell stretches from the apical surface to the basement membrane. Stratified Squamous Epithelium: 1.

Obtain a slide of the skin. The outer layer of the skin, the epidermis, is composed of multiple layers of flattened cells. As the cells are pushed higher, they flatten more and eventually die, composing the outer dead layers of the epidermis. The cells die due to the loss of nutrients, whose source is located in the connective tissue underneath.

Transitional Epithelium: 1. Obtain a slide of the bladder. The inner lining of the bladder is composed of rounded cells that resemble a mix of cuboidal and columnar shaped cells. This is transitional epithelium. This tissue can stretch and distend when necessary without causing gaps or perforations in the lining.

Connective Tissue: Connective tissue is the most abundant and widely distributed tissue type found in the human body. The role of connective tissue is to protect, support, and bind together parts of the body. While other functions are attributed to connective tissues, these are the main ones and the ones we should focus on in our study.

When considering the characteristics that make a tissue a connective tissue, we should consider the following: Connective tissues tend to be very vascular have a rich blood supply. Some exceptions, such as tendons, ligaments, and cartilages, are less vascularized, but overall, connective tissues possess a great blood supply than the epithelial tissue previously discussed.

Connective tissues are made up of many types of specialized cells. Connective tissues contain a large amount of non-living material referred to as the matrix composed of ground substance and fibers.

Typically, this material is manufactured and secreted by the cells of the specific connective tissues. There are four types of connective tissues found in the human body: 1. Connective tissue proper a. Loose Connective Tissue i. Areolar ii. Adipose iii. Reticular b. Dense Connective Tissue i.

Dense regular ii. Dense irregular iii. Elastic 2. Cartilage a. Hyaline b. Elastic c. Fibrocartilage 3. Bone osseous tissue 4. Obtain a slide of areolar tissue and proper mount it on the slide. Notice as you examine the tissue that it is composed of a jumble of fibers and cells. Areolar tissue is a loose connective tissue type and has a very diffuse arrangement. These are the cells responsible for secreting the fibers present. The larger fibers typically pink are called collagen fibers.

The small black fibers are elastic fibers. Collectively, the fibers and the rest of the substance surrounding the cells would be referred to as the matrix. Adipose Tissue: 1. Obtain a slide of adipose tissue or use a kidney or trachea slide.

Use proper technique to mount the slide and locate the tissue. Adipose tissue appears as large, irregular, bubble-like cells lumped together. The cells that you are observing are suspended in a matrix similar to the previous slide. The cells themselves are filled with fat, which is used as stored energy, insulation, and protection. Reticular Tissue: 1. Obtain a slide of reticular tissue. Use proper technique to place the slide on the stage and locate the tissue.

Notice the evident cells reticular cells and the large, dark fibers reticular fibers. These fibers form a soft internal skeleton that support the cells of certain organs, such as the spleen, lymph nodes, and bone marrow.

Dense Regular Connective Tissue: 1. Obtain a slide of a tendon. Use proper technique to mount the slide and to locate the tissue. Notice the orderly fibers running throughout the tissue. These fibers are collagen fibers. Embedded within the fibers are the fiber-producing cells called fibroblasts. This tissue forms tendons and ligaments needed to connect muscles to bones and bones to other bones.

Dense Irregular Connective Tissue: 1. Obtain a slide of skin.