Histology - tissues I

Histological technique

The process of preparing tissue samples for microscopic examination.

Fixation

Chemical preservation of tissues to prevent disintegration and prepare them for further processing.

Dehydration

Removal of free water from tissues to prepare them for embedding in hydrophobic substances.

Clearing

Removal of dehydration substances from tissues to make them translucent or transparent.

Impregnation

Treatment of tissues with stiffening substances, such as paraffin, to allow thin sectioning.

Staining

Application of different dyes to highlight specific structures in tissues.

Diversity of human cells

Variations in shape, nucleus position, special features, and location to other cells.

Factors determining morphology

Environment, functions, and cytoskeleton influence the shape of cells.

Epithelial tissue

Tissue that covers and lines organs, characterized by polarized cells and specialized structures.

Connective tissue

Tissue that supports and connects other tissues, composed of cells and extracellular matrix.

Muscle tissue

Tissue responsible for movement, composed of contractile cells.

Nerve tissue

Tissue that transmits electrical signals, composed of neurons and supporting cells.

Basement membrane

Barrier and filter between epithelium and other tissues, composed of basal and reticular laminas.

Intercellular junctions

Specialized structures that connect epithelial cells and strengthen tissue.

Specialized structures of apical pole

Microvilli, stereocilia, and cilia that increase surface area or facilitate movement.

Stratified squamous nonkeratinized epithelium

Moist epithelium found in oral cavity, vagina, esophagus, anus, and cornea.

Stratified squamous keratinized epithelium

Dry epithelium found in the epidermis of the skin.

Transitional epithelium

Stretchable epithelium found in calyces of kidneys, ureters, and bladder.

Glandular epithelium

Epithelium specialized for secretion, either endocrine or exocrine.

Microvilli

Extensions of the cell membrane that increase the surface area of epithelial cells.

Basal pole

The region of a cell or gland that contains organelles and the nucleus.

Apical pole

The region of a cell or gland that contains secretory granules.

Simple glands

Glands that have one duct and a secretory portion.

Compound glands

Glands that have a duct with branches and a secretory portion.

Tubular secretory portion

A secretory portion of a gland that is shaped like a tube.

Acinar secretory portion

A secretory portion of a gland that is shaped like a sac or acinus.

Tubuloacinar secretory portion

A secretory portion of a gland that has both tubular and acinar structures.

Merocrine secretion

A type of secretion where the cell secretes its contents without affecting the cell itself.

Apocrine secretion

A type of secretion where the cell secretes its contents and loses part of its cytoplasm and plasma membrane.

Holocrine secretion

A type of secretion where the cell disintegrates upon secretion.

Connective tissue

A type of tissue that supports, connects, and protects other tissues and organs in the body.

adipose tissue

A type of connective tissue that provides padding and insulation.

Bone tissue

A type of connective tissue that forms the skeleton and provides support and protection.

Tendon

A type of connective tissue that connects muscle to bone.

Blood

A type of connective tissue that transports oxygen, nutrients, and waste products throughout the body.

Cartilage

A type of connective tissue that provides support and flexibility to various parts of the body.

Fibrous connective tissue

A type of connective tissue that is found between cells and structures and has various functions.

Collagen

A fibrous protein that provides strength and support to tissues.

Loose connective tissue

A type of fibrous connective tissue that has a loose arrangement of fibers and cells.

Dense connective tissue

A type of fibrous connective tissue that has a dense arrangement of fibers and cells.

Regular connective tissue

A type of dense connective tissue that has fibers arranged in a parallel fashion.

Irregular connective tissue

A type of dense connective tissue that has fibers arranged in a random fashion.

Elastic connective tissue

A type of connective tissue that contains elastic fibers and provides elasticity to organs.

Specialized connective tissue

A type of connective tissue that has specific functions and characteristics.

Blood and lymph

Specialized connective tissues that transport fluids and immune cells throughout the body.

Adipose tissue

Specialized connective tissue that stores fat and provides insulation and cushioning.

Reticular tissue

Specialized connective tissue that forms a network or framework for other cells and tissues.

Skeletal tissue

Specialized connective tissue that forms the framework of the body and allows for movement.

Cartilage

Specialized connective tissue that provides support and flexibility to various parts of the body.

Embryo

The early stage of development of an organism.

Mesenchyme

Embryonic connective tissue that gives rise to all adult connective tissues.

Mucous connective tissue

Embryonic connective tissue found in the umbilical cord.

Extracellular matrix

The non-cellular component of connective tissue that provides structural support and regulates cell behavior.

Ground substance

The gel-like substance in the extracellular matrix that fills the spaces between cells and fibers.

Glycosaminoglycans (GAGs)

Long chains of disaccharides that make up part of the ground substance.

Proteoglycans

Molecules made up of chains of amino acids that are connected to GAGs in the extracellular matrix.

Glycoproteins

Proteins that have carbohydrates attached to them and help strengthen and stabilize tissues.

Collagen fibers

Fibers made up of collagen protein that provide strength and support to tissues.

Elastic fibers

Fibers made up of elastin and fibrillin proteins that provide elasticity to tissues.

Reticular fibers

Fibers made up of type III collagen that form a network in immune system and hematopoietic tissues.

Glands

Organs or structures that produce and secrete substances.

Immune system

The body's defense system against pathogens and foreign substances.

Bone marrow

The soft tissue found inside bones that produces blood cells.

Resident cells

Cells that permanently reside in a particular tissue or organ.

Fibroblast

A type of resident cell in connective tissue that actively synthesizes components of the extracellular matrix.

Fibro

Langerhans cells

Cells found in the epidermis that play a role in immune protection.

Macrophages

Cells found in the lungs, nerve tissue, and synovial joints that protect against microbes, toxins, parasites, and cancer cells.

Diapedesis

The ability of cells to slip between capillary walls and reside in the plasma after being released from the bone marrow.

Chemotaxis

The movement of cells in response to a chemical signal.

Leukocytosis

An increase in the number of white blood cells in response to an infection.

Major Histocompatibility Complex (MHC)

A complex that binds to peptide fragments from antigens for recognition by T-cells and activation of an immune response.

B-cells

Cells that recognize antigens in their native form and use membrane-bound immunoglobulins to recognize free antigens in the blood or lymph.

T-cells

Cells that recognize antigens in a processed form, presented by an antigen-presenting cell's MHC molecule to the T-cell receptor.

Antigens

Genetically foreign materials that generate an immune response, such as proteins, viruses, foreign cells, and tumor cells.

Antibodies

Proteins, specifically plasma globulins, that recognize antigens.

IgA, IgD, IgE, IgG, IgM

Different types of immunoglobulins (antibodies) with specific functions.

Blood platelets

Small cell fragments that play a role in coagulation and attach to blood vessel walls.

Thrombocytopenia

A condition characterized by a reduced number of platelets.

Hemopoiesis

The process of blood cell formation.

Stem cells

Unspecialized cells with the ability to differentiate into specialized cells.

Plasticity

The ability of stem cells from one type of tissue to transform into stem cells of another tissue.

Lineage of stem cells

Stem cells that retain the ability to divide without differentiation into specialized cell types.

Erythrocytopoiesis

The development of red blood cells from proerythroblasts to reticuloblasts to erythrocytes.

Granulocyte

A type of white blood cell that includes myeloblasts, promyelocytes, myelocytes, and metamyelocytes.

Megakaryocyte

A large cell that gives rise to platelets.

Monocyte

A type of white blood cell that develops from monoblasts to promonocytes to monocytes.

Aplastic anemia

A condition characterized by bone marrow failure and low counts of erythrocytes, platelets, and leukocytes.

Pancytopenia

A condition characterized by low counts of both erythroid and myeloid series cells.

Lymph

A fluid similar to blood plasma that contains lymphocytes and passes through lymph nodes.