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Tissues of the Body

Tissues of the Body. Epithelial Tissue. General characteristic of epithelial tissue Formed of crowded cells with little intercellular substance in-between. Not penetrated by blood vessels ( avascular ). Nerve fibers can penetrate between the cells.

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Tissues of the Body

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  1. Tissues of the Body

  2. Epithelial Tissue

  3. General characteristic of epithelial tissue Formed of crowded cells with little intercellular substance in-between. Not penetrated by blood vessels (avascular). Nerve fibers can penetrate between the cells

  4. 3. Separated from underlying C.T. by a basement membrane which may be clear or no clear. 4. Has high power of regeneration rate. Origin: - Ectoderm (skin) - Endoderm (GIT) - Mesoderm (serous membrane)

  5. Types of Epithelial tissue:A) Surface Epithelium: Cover surface or line cavity. It may be:1.Simple Epithelium: One layer of cells.2. Stratified Epithelium: Many layers of cells.B) Glandular Epithelium: secretory functionC) Neuro-epithelium: act as a receptor.D) Myo-epithelium: contractile function.

  6. A) Simple epithelium: classified according to shape: 1- Simple squamous: Formed of one layer of flat cells with flat nuclei. Sites:1. Lung alveoli: (for gaseous exchange). 2. Endothelium: Line heart & blood vessels. (for gaseous exchange & smooth surface for flow) 3. Mesothelium of serous membranes (as pleura) 4. Bowman,s capsule of kidney.

  7. 2- Simple cubical epithelium: a layer of cubical cells with central rounded nuclei. Sites: 1.Thyroid follicle (secretion). 2. convoluted tubules of kidney (reabsorption). 3. Medium sized ducts of glands.

  8. 3- Simple columnar: Columnar cells, basal oval nuclei. Sites: mainly in digestive system Stomach, small & large intestine. Gall bladder & large bile duct 4-Simple columnar ciliated: The free surface of columnar cells are covered with cilia. Sites: uterus & fallopian tube (female genital T.) 2.Lung bronchioles

  9. 5-Pseudostratified columnar epith: Columnar cells are so crowded that some of them don't reach surface, so nuclei appear at different levels gives false stratification. It is simple epithelium because all rest on basement membrane. Site: in male genital tract line vas deferens & membranous urethra.

  10. 6- Pseudostratified col. ciliated epithelium: The free surface of columnar cells are covered with cilia. with goblet cells. Sites: upper respiratory tract.

  11. II. Stratified Epithelium: Several layers of cells

  12. 1-Transitional epithelium: • Consisted of 4-8 layers. • Basement membrane is indistinct (not clear). • Basal cells: short columnar with basal rounded nuclei. • Intermediate cells: polygonal with central rounded nuclei. intercellular spaces contain mucoid like substance, allow gliding of cells.

  13. So during distension of the organ, it is formed of 2 to 3 layers • Superficial cells: large cuboidal with central rounded nuclei, may binucleated. Sites: Lining the urinary tract: renal pelvis, ureter, urinary bladder, prostatic male urethra.

  14. 2- Stratified squamous epithelium: • Formed of 5-30 layers. • Rest on clear wavy basement membrane. • Basal cells are columnar with basal oval nuclei. • Intermediate layers: polygonal cells & central rounded nuclei. connected together by desmosomes & become smaller near surface.

  15. Intermediate layers: polygonal cells & central rounded nuclei. Attached together by desmosomes. Cells smaller near surface. • Superficial layers squamous with flat nuclei. Types: Non keratinizing:. In mouth, tongue Keratinizing:In skin, external ear and nose.

  16. 4-Stratified columnar epithelium: • Similar to stratified squamous epith but the superficial cells are columnar. • Non-ciliated: • cavernous (penile) male urethra. • Ciliated: in fetal oesophagus • & soft palate.

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