Histo Script RSU_1-10

The rate of cell turnover (death) equals the rate of cell replacement.

Other stem cells and cells that will differentiate and undergo keratinization.

Generative phase (stem cells in Stratum basale), Synthetic phase, Degenerative phase (Stratum corneum).

Approximately 20-30 days.

Various growth factors such as EGF and PDGF.

A steady state relative to the number of cells in the epithelium and its thickness.

20-30 days in the skin, 4-6 days in the small intestine and oral mucosa.

The epithelium cannot resurface, as seen in third-degree burns.

Epithelium, Connective tissue, Muscle, Nervous.

In the lining of blood vessels and lymphatic vessels (endothelium) and the lining of serous body cavities (mesothelium).

Protection, transcellular transport, secretion, absorption, control of movement, sensory detection.

Epithelium, connective tissue, muscle, and nervous tissue.

The cilia propel a surface layer of mucus containing entrapped particles towards the pharynx, often described as the mucociliary escalator.

Dense irregular connective tissue and dense regular connective tissue.

All three germ layers: ectoderm, endoderm, and mesoderm.

Cells (fibroblasts and others), fibers, and ground substance (extracellular matrix).

Fixed cells are a resident population of cells that have developed and remain in place within the connective tissue, where they perform their functions.

Firstly, the individual cells exhibit polarity with nuclei mainly confined to the basal two-thirds of the epithelium. Secondly, cilia are never present on true stratified epithelia.

In the dermis.

Cells in close apposition, rest on a basement membrane, adhesive, avascular, polarized sheets.

Architectural framework of the body, binding and providing mechanical support for other tissues, wound repair, and inflammatory response.

It covers the cornea of the eye, lies upon connective tissue with a smooth, regular surface, and constitutes 5-7 layers of cells with flattened cells appearing at the surface.

Fibroblasts, Adipose cells, Pericytes, Mast cells, Tissue macrophages.

Based on the shape of apical cells (squamous, cuboidal, columnar) and arrangement of cells (simple, stratified, pseudostratified, transitional).

Less oriented.

Mesenchyme is the embryonic connective tissue from which all types of supporting and connective tissue are derived.

Transient cells originate mainly in the bone marrow and circulate in the bloodstream. They migrate into the connective tissue to perform their specific functions upon receiving the proper stimulus or signal.

Transitional epithelium is found only in the urinary tract in mammals. It has several layers of nuclei, apical cells that bulge into the lumen, and some cells with 2 nuclei. In the non-distended state, it appears about four to five cell layers thick, and in the stretched state, it appears only two or three cells thick.

In tendons.

Gives rise to oral and nasal mucosae, cornea, epidermis of the skin, and glands of the skin and mammary glands.

Mesenchymal cells are stellate-shaped to fusiform, with big, oval, pale, and centrally located nuclei. They have little cytoplasm and extend small processes in several directions, forming a network.

It appears to be stratified but is actually composed of a single layer of cells. All cells are in contact with the basal lamina, but only some reach the surface.

Plasma cells, Lymphocytes, Neutrophils, Eosinophils, Basophils, Monocytes.

More oriented.

Liver, pancreas, and the lining of the respiratory and gastrointestinal tract.

Gap junctions are present where the processes of mesenchymal cells make contact.

They secrete mucus.

Fibroblast.

Uriniferous tubules of the kidney, lining of the male and female reproductive systems, endothelial lining of the circulatory system, and mesothelium of body cavities.

Tendons.

Fibers (collagen, elastic, reticular), ground substance (glycosaminoglycans, proteoglycans, adhesive proteins), and tissue fluid.

It appears to be about four to five cell layers thick with basal cells roughly cuboidal, intermediate cells pear-shaped, and surface cells large and rounded, possibly containing two nuclei.

The basal lamina is always present, synthesized by epithelial cells, and visible only by TEM.

Fibroblasts synthesize and secrete components of the ECM, including fibers and ground substance. They also secrete growth factors that influence the growth and differentiation of neighboring cells.

Surface modifications reflect functions at those surfaces, such as cilia and keratin.

Flattened cells found between bundles of collagen fibers in tendons.

Inflammatory response, immune response, and wound repair.

It often appears only two or three cells thick, with intermediate and surface layers extremely flattened.

Lamina lucida (Lamina rara) and Lamina densa.

Hard connective tissues and soft connective tissues.

Stratified squamous keratinized epithelium.

Active fibroblasts are fusiform cells with many cytoplasmic processes, pale-staining cytoplasm, large darker-stained ovoid euchromatic nucleus, and prominent nucleolus.

Bundles of collagen surrounded by tendoblasts.

It is translucent, closest to the cell membrane, and contains fine strands that connect the cell to the lamina densa.

Adipose tissue serves as a site for energy storage.

Many primary bundles enveloped by loose connective tissue (perithenonium).

Inactive fibroblasts (fibrocytes) are smaller with darker elongate nuclei and acidophilic cytoplasm, making them hard to distinguish from the matrix they have already synthesized.

It is an electron-dense layer (20-100 nm) with a meshwork of randomly-woven 4 nm filaments (Type IV collagen).

Proteins of keratin-containing intermediate filaments found in the intracytoplasmic cytoskeleton of epithelial tissue.

Collagen fibers are composed of fiber-forming collagen proteins.

Histamine, growth and inflammatory factors, heparin, and other enzymes and proteins.

The reticular lamina is not always present, contains reticular fibers, and is made by underlying connective tissue cells.

20 different cytokeratins.

Type III collagen.

Antigens.

Type IV collagen.

Two groups: acidic cytokeratins (type A, 9-20) and basic cytokeratins (type B, 1-8).

Elastic fibers are composed of elastin and fibrillin proteins.

Storage in secretory granules and regulated release (degranulation) of histamine and other vasoactive mediators of inflammation.

Laminin is a cross-shaped multiadhesive glycoprotein primarily in the lamina lucida, acting as a 'glue' between the cell membrane (integrins) and the lamina densa (type IV collagen).

A type A cytokeratin together with a type B cytokeratin.

Elastic fibers are deformable, meaning they can stretch and recoil.

Bone marrow precursor.

Integrins are a family of trans-membrane linker proteins that function as matrix receptors (e.g., fibronectin receptor, laminin receptor, collagen receptor).

Hair follicle stem cells.

Adhesion of epithelial cells to underlying connective tissue, selective permeability barrier, substrate for cell migration, and barrier to metastatic potential of epithelial cancer cells.

Immediate hypersensitivity response characteristic of allergies, asthma, and anaphylactic shock.

By the correct combination of cytokeratin antibodies or with antibodies directed against a single cytokeratin.

In the skin (dermis) and peritoneal cavity.

Apical surface: microvilli, cilia, stereocilia; Lateral surface: intercellular junctions; Basal surface: basement membrane, junctional specializations, plasma membrane interdigitations.

Based on the cytokeratins present.

Microvilli are finger-like processes extending from the apical surface (1-2 μm in length) with a core of actin filaments, increasing surface area in absorptive epithelium.

In the mucosa of the digestive and respiratory tracts.

Cilia are long (5-10 μm) cytoplasmic extensions with a complex arrangement of microtubules (9+2 axoneme) that facilitate the flow of fluid over an epithelium.

Plasma cells are mature B lymphocytes that constitutively secrete antibodies.

Epithelia.

Large, ovoid cells, 20 μm in diameter, with an eccentrically placed nucleus, and a relatively short lifespan of 2 to 3 weeks.

Exocrine glands and endocrine glands.

Large eccentric heterochromatic 'cartwheel' nucleus.

Collagen fibers.

Via ducts onto the external or internal epithelial surface from which they originated.

Specialized for the storage and release of energy.

Collagen fibers are flexible, unbranched, and have very high tensile strength.

Into the blood or lymphatic vessels for distribution.

Promotes the release of energy as heat (thermogenesis).

Bundles of threadlike fibrils bound together by non-fibrillar collagen and proteoglycans.

Mucus-secreting goblet cells.

Secretion of several proteins called adipocytokines (e.g., leptin, adipsin, resistin).

Tropocollagen.

They consist of clusters of secretory cells arranged in varying degrees of organization.

In newborns and small amounts in adults.

Elastic fibers are thinner than collagen fibers, branched, and deformable (can stretch and recoil).

Simple glands (unbranched duct) and compound glands (highly branched duct system).

Promotes the release of energy as heat.

In ligaments, lung, skin, bladder, and walls of blood vessels.

Tubular, acinar (alveolar), and tubuloalveolar.

Type III collagen.

Serous, mucous, and mixed.

Reticular cells (specialized fibroblasts) and vascular smooth muscle cells.

It involves the process of exocytosis where secretory granules leave the cell with no loss of other cellular material.

They link the extracellular matrix (ECM) to the cell via integrin receptors.

It involves the discharge of free, unbroken, membrane-bound vesicles containing secretory product.

Glycosaminoglycans, proteoglycans, and adhesive glycoproteins.

It involves the discharge of whole secretory cells with subsequent disintegration of the cells to release the secretory product.

Long unbranched polymers of repeating disaccharides.

A thin sheet of extracellular material at the basal surface of all epithelia.

Protein cores to which various glycosaminoglycans are covalently linked.

Basal lamina and reticular lamina.

Sulfated (e.g., keratan sulfate, heparan sulfate) and nonsulfated (e.g., hyaluronic acid).

It separates epithelia from the underlying connective tissue and serves as a structural attachment site.

Huge macromolecules formed by proteoglycans covalently linked to hyaluronic acid, responsible for the gel state of the extracellular matrix.

Laminin (basal lamina), chondronectin (cartilage), osteonectin (bone), and fibronectin (generally dispersed throughout the ECM).

They originate in bone marrow, circulate as monocytes, and become macrophages when they migrate into tissues.

Phagocytose and destroy dead cells and other foreign material, and present antigens to T lymphocytes.

1. Phagocytosis of antigen and formation of phagocytic vesicle. 2. Degradation of antigen in lysosome and binding of antigen peptides to MHC receptor. 3. Interaction of antigen peptide bound to MHC receptor on plasma membrane with lymphocyte.