SGU Histology

• -Surrounded by cell membrane
• -Composed of nucleus and cytoplasm (organelles and inclusions)
• -Cellular shape, size and structure vary

• -8 to 10 nm in width
• -trilaminar consisting of outer, inner electron-dense lamina and electron-lucent intermediate lamina
• -consists of 2 leaflets of phospholipid molecules
• -integral transmembrane protein and peripheral membrane protein associated with bilayer

• -glycolipid and glycprotein
• -present in external leaflet of cell membrane
• -protects cell from mechanical and chemical damage

• -selectively permeable
• -special receptor sites for antigen recognition and immunological mechanisms (phagocytosis)
• -special receptor sites for hormone activated cellular events

• -bounded by nuclear envelope, contains chromatin, nucleolus, nuclear matrix
• -most are spherical or ovoid; can be spindle-shaped (smooth muscle), bean shaped (monocytes), or multilobulated (neutrophil leucocytes)
• -skeletal muscle cells and osteoclasts have several nuclei
• -mammalian erythrocytes lack nuclei

• -consists of 2 concentric membranes separated by 25 nm-wide perinuclear space
• -outer membrane: ribosomes, continuous with RER
• -inner membrane: bound to membrane proteins to which specific sites of chromatin are attached
• -interrupted by pores which provide selective and active transport between nucleus and cytoplasm

• -composed of DNA, basic proteins, histones/nonhistone chromosomal proteins
• -heterochromatin: in basophilic clumps, in relatively inactive cells
• -euchromatin: in active cells, lightly stained, uniformly dispersed

-sex chromatin prominent in neutrophils in females

• -spherical and basophilic structure
• -prominent in cells that are actively synthesizing protein
• -composed of DNA loops; contains rRNA genes
• -involved in rRNA synthesis

• -small electron-dense cytoplasmic particles (15-25 nm in dia.)
• -occur as ribosome or polyribosomes
• -occur freely in cytoplasm or with RER
• -all cells except mammalian erythrocytes contain ribosomes
• -function: protein synthesis

• -network of tubules, bounded by membranes with ribosomes
• -aggregates of RER appear basophilic, involved in protein synthesis
• -after ribosomes are surrounded by membrane, branches off to form secretory vesicle then goes to the lumen by exocytosis

• -abundant in cells involved in lipid metabolism
• -enzymes for synthesis of steroid hormones located on membranes of smooth ER
• -involved in drug detoxification
• -involved in release and recapture of calcium ion during contraction/relaxation of muscles

• -can be stained with silver salt or osmium; appears as black network of cisternae
• -consists of parallel membranes bounded by flattened cisternae, tubules, and vesicles
• -function: site for accumulation, concentration, and packaging of secretory proteins into membrane bound vesicles (FedEX)
• -function: biosynthesis of glyco-proteins/lipids, phospholipids, and neutral lipids

• -membrane-bounded vesicles that contain various hydrolytic enzymes (nucleases, proteases, lipases)
• -enzymes are synthesized in RER, transferred to golgi apparatus where modified and packaged as primary lysosomes
• -fuse with phagocytosed material, composite structure termed secondary structure
• -after digestion, contents of secondary lysosomes retained as lipofuscin (age pigment)

• -small membrane-bounded organelles, containing oxidase and catalase enzymes which synthesize and destroy H2O2
• -energy derived from oxidation used for metabolic processes
• -abundant in hepatocytes and cells of proximal convoluted tubules of kidney
• -detoxify certain substances (i.e. ethanol); plays role in gluconeogenesis

• -stained with Janus Green B in living cells
• -chief source of energy, ATP synthesis
• -inner membrane thrown into cristae which contains enzymes that function oxidative phosphorylation
• -mitochondrial matrix contains DNA, ribosomes, respiratory enzymes
• -lacking mitochondria -> muscular dystrophy

• -composed mainly of actin and myosin filaments, cause cellular contraction in muscle cells
• -form a thin sheath just below plasmalemma, associated with endocytosis, exocytosis, cell migratory activity

• -keratin filaments provide mechanical stability by formation of desmosomes
• -also present in keratinized epithelium for protection

-support muscle cells

-support nerve cells

-supports astrocytes and neurolemmocytes (Schwann cells)

• -play significant role in maintenance of cell form and transport of organelles and vesicles (secretory granules)
• -play essential role in cell division; major component of the centriole
• -centriole comprised of 9 groups of 3 microtubules in longitudinal and parallel arrangement

-in liver cell and muscle, can be demonstrated by PAS reaction

-in adipose cells, can be demonstrated with osmic acid fixation

-in skin and pigment epithelium of retina

-result of hemoglobin degradation

• -indigestible residue of phagocytosis commonly found in cardiac muscle, liver an nerve cells
• -pigment increases with age

• -found in epithelial cells, consists of irregularly anastamosing ridges (transmembrane protein) that seal neighboring cells together in a beltlike fashion
• -constitutes a barrier to prevent passage of water soluble molecules from lumen to intercellular space

• -zonula adherens: cells held together by transmembrane protein linker and bundle of actin filaments run parallel to junctional cell membrane (prominent in lining cells of intestines)
• -desmosomes: transmembrane protein linker and intercellular electron-dense plaque, forms hairpin loop
• -hemidesmosomes: connect the cells from extracellular matrix protein

• -permit direct passage of inorganic ions, water soluble molecules from cell to cell
• -intercellular space bridged by interlocking transmembrane proteins of apposed membrane

• -one way passage
• -found in respiratory, male and female system
• -surrounded by plasma membrane, composed of 9 doublet microtubules around 2 central microtubules
• -basal body is located at the BASE of the cilia, resembling centrioles

• -single long cilium
• -responsible for movement
• -i.e. spermatozoon

• -cytoplasmic evagination to increase the free surface for absorption
• -i.e. small intestines

• -long, rigid microvilli
• -i.e. hair cells of spiral organ (corti) of inner ear

• -consists of sheets of aggregated cells of similar type
• -rests on basement membrane (PAS technique or silver salt staining)
• -lamina lucida (thin, semi-transparent) + lamina densa (composed of proteoglycans, type of collagen) = subbasal lamina (composed of reticular fibers)
• -function: protection, absorption, secretion, diffusion, strengthen membrane

• -thin, flat, scale-like cells
• -spherical or oval nucleus gives slightly bulging appearance
• -i.e. lining of blood vessels, pleural and peritoneal cavities, pulmonary arteries, glomerular capsule

• -cuboidal cells with centrally placed nucleus
• -i.e. thyroid gland, collecting kidney ducts

• -tall, narrow cells
• -nucleus is oval, located near base of cell
• -i.e. stomach, intestines, gall bladder

• -single layer of cells, but because of different cell shape and nuclei location, gives impression of stratified epithelium
• -in trachea and bronchii (ciliated form)

• -several layers of cells with most superficial cells having squamous shape
• -i.e. skin (keratinized form - cannot see nucleus), cornea (non-keratinized)

• -i.e. lining of extretory ducts of glands
• -mostly 2 layers

-i.e. in parotid and mandibular gland ducts

• -lines certain hollow organs, capable of considerable distension
• -i.e. urinary bladder and urethra
• -in relaxed state, superficial cells are dome-shaped and bulge into lumen
• -when stretched, reduced to only few layers of flattened cells

-consists of glandular or secretory epithelium and duct system (parenchyma) with supportive framework of connective tissue (stroma)

• -unicellular and multicellular glands
• -endocrine (ductless gland, secretion released into intercellular fluid and transported to site of action by blood) and exocrine (duct system)
• -simple or compound gland

• -produces mucous
• -unicellular

-i.e. large intestine

i.e. sweat glands

-i.e. stomach

-i.e. sebaceous gland

-i.e. large sebaceous gland

-i.e. minor salivary gland of oral cavity

-i.e. parotid gland

-i.e. pancreas

• -intralobular (striated in salivary glands and intercalated ducts in pancreas)
• -interlobular
• -lobar ducts
• -main ducts

• -produce thin, watery secretion
• -spherical nuclei in center or lower half and their apical cytoplasm is filled with small secretory granules
• -i.e. parotid salivary gland

• -produce thick, viscous secretion that form a protective covering
• -stain lightly with H&E because of mucin
• -nuclei are flattened and displaced towards basal part of cell

• -both have serous an mucous acini
• -serous cells are located over the mucous acini as serous demilunes
• -i.e. in the mandibular salivary gland

• -secretory granules enclosed in a membrane
• -discharged by exocytosis

• -membrane-bounded granule
• -together with a rim of cytoplasm and plasmalemma is released from the APEX of the cell
• -i.e. sweat and mammary glands

• -entire cell is released as the secretory product (highly dividing)
• -i.e. sebaceous glands

• -secretory material from one cell is transferred from one cell to the cytoplasm of another cell
• -i.e. transfer of melanin pigment from melanocytes into keratinocytes

• -interposed between the secretory cells and basement membrane
• -when contracted, these cells force the secretory product into the duct system