Other stem cells and cells that will differentiate and undergo keratinization.
Epithelium, connective tissue, muscle, and nervous tissue.
In the dermis.
Mesenchyme is the embryonic connective tissue from which all types of supporting and connective tissue are derived.
Plasma cells, Lymphocytes, Neutrophils, Eosinophils, Basophils, Monocytes.
Gap junctions are present where the processes of mesenchymal cells make contact.
Fibers (collagen, elastic, reticular), ground substance (glycosaminoglycans, proteoglycans, adhesive proteins), and tissue fluid.
Cells in close apposition, rest on a basement membrane, adhesive, avascular, polarized sheets.
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.
The basal lamina is always present, synthesized by epithelial cells, and visible only by TEM.
Active fibroblasts are fusiform cells with many cytoplasmic processes, pale-staining cytoplasm, large darker-stained ovoid euchromatic nucleus, and prominent nucleolus.
The reticular lamina is not always present, contains reticular fibers, and is made by underlying connective tissue cells.
Generative phase (stem cells in Stratum basale), Synthetic phase, Degenerative phase (Stratum corneum).
Protection, transcellular transport, secretion, absorption, control of movement, sensory detection.
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.
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.
Stratified squamous keratinized epithelium.
Histamine, growth and inflammatory factors, heparin, and other enzymes and proteins.
Storage in secretory granules and regulated release (degranulation) of histamine and other vasoactive mediators of inflammation.
By the correct combination of cytokeratin antibodies or with antibodies directed against a single cytokeratin.
Collagen fibers.
Mucus-secreting goblet cells.
Tubular, acinar (alveolar), and tubuloalveolar.
It involves the discharge of whole secretory cells with subsequent disintegration of the cells to release the secretory product.
20-30 days in the skin, 4-6 days in the small intestine and oral mucosa.
Less oriented.
Liver, pancreas, and the lining of the respiratory and gastrointestinal tract.
Fibroblast.
Inflammatory response, immune response, and wound repair.
Type IV collagen.
Integrins are a family of trans-membrane linker proteins that function as matrix receptors (e.g., fibronectin receptor, laminin receptor, collagen receptor).
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.
Epithelia.
Into the blood or lymphatic vessels for distribution.
Elastic fibers are thinner than collagen fibers, branched, and deformable (can stretch and recoil).
It involves the process of exocytosis where secretory granules leave the cell with no loss of other cellular material.
Sulfated (e.g., keratan sulfate, heparan sulfate) and nonsulfated (e.g., hyaluronic acid).
Phagocytose and destroy dead cells and other foreign material, and present antigens to T lymphocytes.
The epithelium cannot resurface, as seen in third-degree burns.
In the lining of blood vessels and lymphatic vessels (endothelium) and the lining of serous body cavities (mesothelium).
Fixed cells are a resident population of cells that have developed and remain in place within the connective tissue, where they perform their functions.
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.
Tendons.
Lamina lucida (Lamina rara) and Lamina densa.
Many primary bundles enveloped by loose connective tissue (perithenonium).
Proteins of keratin-containing intermediate filaments found in the intracytoplasmic cytoskeleton of epithelial tissue.
Elastic fibers are composed of elastin and fibrillin proteins.
Adhesion of epithelial cells to underlying connective tissue, selective permeability barrier, substrate for cell migration, and barrier to metastatic potential of epithelial cancer cells.
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.
Exocrine glands and endocrine glands.
Epithelium, Connective tissue, Muscle, Nervous.
Dense irregular connective tissue and dense regular connective tissue.
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.
In tendons.
They secrete mucus.
Flattened cells found between bundles of collagen fibers in tendons.
It is an electron-dense layer (20-100 nm) with a meshwork of randomly-woven 4 nm filaments (Type IV collagen).
Antigens.
Bone marrow precursor.
Collagen fibers are flexible, unbranched, and have very high tensile strength.
In newborns and small amounts in adults.
Reticular cells (specialized fibroblasts) and vascular smooth muscle cells.
Basal lamina and reticular lamina.
They originate in bone marrow, circulate as monocytes, and become macrophages when they migrate into tissues.
Various growth factors such as EGF and PDGF.
All three germ layers: ectoderm, endoderm, and mesoderm.
Fibroblasts, Adipose cells, Pericytes, Mast cells, Tissue macrophages.
Gives rise to oral and nasal mucosae, cornea, epidermis of the skin, and glands of the skin and mammary glands.
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.
Bundles of collagen surrounded by tendoblasts.
20 different cytokeratins.
A type A cytokeratin together with a type B cytokeratin.
Apical surface: microvilli, cilia, stereocilia; Lateral surface: intercellular junctions; Basal surface: basement membrane, junctional specializations, plasma membrane interdigitations.
Via ducts onto the external or internal epithelial surface from which they originated.
Tropocollagen.
A thin sheet of extracellular material at the basal surface of all epithelia.
The rate of cell turnover (death) equals the rate of cell replacement.
A steady state relative to the number of cells in the epithelium and its thickness.
Cells (fibroblasts and others), fibers, and ground substance (extracellular matrix).
Based on the shape of apical cells (squamous, cuboidal, columnar) and arrangement of cells (simple, stratified, pseudostratified, transitional).
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.
Uriniferous tubules of the kidney, lining of the male and female reproductive systems, endothelial lining of the circulatory system, and mesothelium of body cavities.
It often appears only two or three cells thick, with intermediate and surface layers extremely flattened.
Adipose tissue serves as a site for energy storage.
Two groups: acidic cytokeratins (type A, 9-20) and basic cytokeratins (type B, 1-8).
Hair follicle stem cells.
In the mucosa of the digestive and respiratory tracts.
Large, ovoid cells, 20 μm in diameter, with an eccentrically placed nucleus, and a relatively short lifespan of 2 to 3 weeks.
Promotes the release of energy as heat (thermogenesis).
Simple glands (unbranched duct) and compound glands (highly branched duct system).
They link the extracellular matrix (ECM) to the cell via integrin receptors.
It separates epithelia from the underlying connective tissue and serves as a structural attachment site.
Approximately 20-30 days.
The cilia propel a surface layer of mucus containing entrapped particles towards the pharynx, often described as the mucociliary escalator.
Architectural framework of the body, binding and providing mechanical support for other tissues, wound repair, and inflammatory response.
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.
More oriented.
Surface modifications reflect functions at those surfaces, such as cilia and keratin.
It is translucent, closest to the cell membrane, and contains fine strands that connect the cell to the lamina densa.
Type III collagen.
Elastic fibers are deformable, meaning they can stretch and recoil.
Based on the cytokeratins present.
Specialized for the storage and release of energy.
They consist of clusters of secretory cells arranged in varying degrees of organization.
Serous, mucous, and mixed.
Protein cores to which various glycosaminoglycans are covalently linked.
Hard connective tissues and soft connective tissues.
Inactive fibroblasts (fibrocytes) are smaller with darker elongate nuclei and acidophilic cytoplasm, making them hard to distinguish from the matrix they have already synthesized.
Collagen fibers are composed of fiber-forming collagen proteins.
Immediate hypersensitivity response characteristic of allergies, asthma, and anaphylactic shock.
Plasma cells are mature B lymphocytes that constitutively secrete antibodies.
Large eccentric heterochromatic 'cartwheel' nucleus.
In ligaments, lung, skin, bladder, and walls of blood vessels.
Glycosaminoglycans, proteoglycans, and adhesive glycoproteins.
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).
In the skin (dermis) and peritoneal cavity.
Secretion of several proteins called adipocytokines (e.g., leptin, adipsin, resistin).
Type III collagen.
Long unbranched polymers of repeating disaccharides.
Bundles of threadlike fibrils bound together by non-fibrillar collagen and proteoglycans.
Promotes the release of energy as heat.
It involves the discharge of free, unbroken, membrane-bound vesicles containing secretory product.
Huge macromolecules formed by proteoglycans covalently linked to hyaluronic acid, responsible for the gel state of the extracellular matrix.
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.
Laminin (basal lamina), chondronectin (cartilage), osteonectin (bone), and fibronectin (generally dispersed throughout the ECM).
