Lecture 7: Epithelial and Connective Tissues PDF

II- Stratified epithelium Ø Consist of several layers of cells Ø The basal layer termed Malpighian layer from which the tissue develops. Ø Malpighian layer rests on the basement membrane. Ø Stratified epithelial are classified according to the structure of the outermost layer of their cells into...

II- Stratified epithelium Ø Consist of several layers of cells Ø The basal layer termed Malpighian layer from which the tissue develops. Ø Malpighian layer rests on the basement membrane. Ø Stratified epithelial are classified according to the structure of the outermost layer of their cells into: 1- Stratified squamous epithelial tissue Ø The deepest layer “ Malpighian layer” consist of columnar cells. Ø The uppermost layer are squamous cells. Ø The intermediate layer are irregular, polyhedral and flattened cells “spongy layer”. Ø It may be keratinized as in the epidermis of skin or non- keratinized as in the esophagus. (spongy layer)  e.g. Oesophagus e.g. Skin 2- Stratified cuboidal epithelial tissue Ø Cells are square-shaped in cross section. Ø Each cell has a central round nucleus. Ø Found in the kidney tubules, bile ducts and ducts of oesophogeal gland. 3- Stratified columnar epithelial tissue Ø Cells of the superficial layer are columnar. Ø Malpighian layer cells are either columnar or irregular in shape. Ø Middle layer are of small, irregular and polyhedral cells. Ø Found in urethra, uterus and ducts of oesophogeal gland.. 4- Stratified ciliated columnar epithelial tissue Ø It is like the stratified columnar epithelium but the superficial layer free surface is provided with cilia. Ø Found in the upper surface of soft palate and larynx. 5- Transitional epithelium Ø Transition state between stratified squamous and columnar epithelial. Ø Found in the wall of hollow organs which are able to contract and stretch. Ø The superficial layer cell are flattened with convex free surface Ø The deepest layer are cuboidal or columnar cells Ø Found in the wall of uterus and urinary bladder  Epithelial tissue 2-Acc. to. function of epithelial tissue Protective / Germinal Glandular Sensory epithelial covering epithelial epithelial epithelial Endocrine gland Exocrine gland 1-Protective /Covering epithelium Ø This type of epithelium protect body vs mechanical stress and infectious agent Ø e.g. Epidermis of skin and endothelium of blood vessel 2-Sensory epithelium Ø This type of epithelium function to receive stimuli and transmit them to the nervous tissue. Ø e.g. skin, eye, ears, and nose  Merkel`s cells -Sensory receptor cells -In basal cell layer of skin epidermis -The sensory nerve fibre reach epidermis and looses its myelin sheath and penetrates the basement membrane under the epidermal cells to terminate as terminal disc under the Merkel`s cell 3-Germinal epithelium Ø This type of epithelium function to produce the germ cells “production of sperm and ova” Ø e.g. gonads i.e., testis and ovary Testis Ovary 4-Glandular epithelium Ø This type of epithelium function to perform a glandular/ secretory function, Glands Endocrine Exocrine glands glands Ø Endocrine glands: do not have duct so secretion pass directly to blood stream. e.g. Adrenal gland, Testis and ovary Ø Exocrine glands: have duct so secretion pass from duct to the blood stream. e.g. sweat and lacrimal glands. Endocrine glands Exocrine glands  Connective Tissue: 1. It is developed from the middle germ layer (Mesoderm). 2. It connect other tissue together and to the skeleton. 3. Does not rest on a basement membrane. 4. Have large a mount of intracellular matrix. Connective tissue Acc. to the nature of intracellular substance Connective tissue Vascular Connective Skeletal connective proper “semifluid tissue” fluid Matrix” Tissue “ Solid Matrix” matrix”  Connective fibers Ø White / collagenous fibers: 1. Formed of collagen protein 2. Are colorless and arranged in bundles which may branch. Ø Yellow / elastic fibers: 1. Formed of elastin protein 2. Yellow in color and found as single branched fibrils  Connective Cells Ø Fibroblast/ fibrocyte 1. The most common type of cells 2. Responsible for the formation of white fibers Ø Mast cells 1. Cytoplasm is granulated 2. Responsible for heparin “ anticoagulant” and histamine “ Allergic response” production Ø Macrophages 1. Amoeboid or irregular shaped cells 2. Protect body against infection by engulfing bacteria and foreign particles Ø Eosinophil 1. G r a n u l a t e d w h i t e b l o o d c e l l s w i t h s t r o n g a ff i n i t y to eosin “acidic dyes” 2. Have a nucleus of two lobes Ø Plasma cells 1. Spherical cells with round or oval eccentric nucleus. 2. Responsible for antibodies production. Ø Lymphocytes 1. Agranulated white blood cells 2. Have a large round nucleus 3. Lymphocytes help your immune system remember every antigen it comes in contact with. 4. Lymphocytes help your immune system remember every antigen it comes in contact with Ø Adipose cells “Fat cells” 1. Spherical in shape with big fat globule 2. The nucleus found in a peripheral position. 3. Reserve the fatty material in the cytoplasm  Connective tissue Acc. to the nature of intracellular substance Connective tissue Vascular Connective Skeletal connective proper “semifluid tissue” fluid Matrix” tissue “ Solid Matrix” matrix”  A-Connective Tissue Proper 1. Also termed loose connective tissue. 2. Have a large a mount of intracellular substance. 3. Subdivided into six types to : I. Areolar connective tissue 1. Found in the peritoneum and surround blood vessels and nerves. II. Fibrous connective tissue 1. The collagen fibers (white fibers) predominate over the elastic fibers. 2. Consist of parallel bundles of white fibers. 3. Found in the tendons that connect muscles to bone. III. Elastic connective tissue 1. The elastic fibers predominate over the collagen fibers. 2. Found in the arteries and ligaments that bind bones together. Iv. Reticular connective tissue 1. Consist of short reticular fibers and lymphocytes. 2. Found in the spleen and bone marrow. V. Mucous connective tissue 1. With intracellular jelly like substance containing mucous and white fibers. 2. Found in the umbilical cord and embryonic organs. VI. Adipose connective tissue 1. Have a large number of adipose cells. 2. Cells appear empty because their fat droplets are dissolved during tissue preparation. 3. Found in the subcutaneous tissue and around kidneys.  B-Vascular Connective Tissue 1. Intracellular substance are liquid called “ Plasma”. 2. Intracellular substance are extensive 3. The cellular part represented by corpuscles which is responsible for plasma formation. Vascular Connective tissue Blood Lymph