Practical Histology EMF 2025 PDF

PRACTICAL HISTOLOGY EMF Anatomy department Taibah University Epithelium  Connective tisssue Mucoid connectivetissue Sites ▪ An embryonic type of connective tissue. ▪ Wharton´ jelly of the umbilical cord (principal co...

PRACTICAL HISTOLOGY EMF Anatomy department Taibah University Epithelium  Connective tisssue Mucoid connectivetissue Sites ▪ An embryonic type of connective tissue. ▪ Wharton´ jelly of the umbilical cord (principal component of umbilical cord). ▪ Pulp cavities of young (growing) teeth (which remain as a postnatal source of mesenchymal stem cells) Structure ▪ Jelly-like type of connective tissue. ▪ Abundant ground substance. ▪ Sparse collagen fibres. ▪ Scattered fibroblasts.  Loose (areolar) connective tissue Characters ▪. Sites ▪ The most common type. ▪ Lamina propria and submucosa of the digestive system. ▪ Fills spaces between muscles and nerve fibres. ▪ In the serous membranes eg peritoneum. Structure Cells, fibres and matrix in nearly equal parts ▪ The most common cell: fibroblast. ▪ The most common fibre: collagen. ▪ Moderate amount of ground substance.  Reticular connective tissue Sites: it forms the stroma of organs (endocrine glands, lymph nodes, liver, and spleen). Structure: ❖ A network of reticular cells and fibres.  Adipose connectivetissue A. Unilocular (white) adipose C.T Sites: ❖ The most common (almost all adipose tissue in adults). Structure: ❖ Incomplete lobules of unilocular adipocytes. ❖ Colour: white to yellow. Function: ❖ Fat storage.  Adiposeconnectivetissue B. Multilocular (brown) adipose T. Sites: ❖ Newborn: 2-5% of body weight. Located mainly in the back, shoulders & neck. ❖ Adults: Greatly reduced. Localized only around the kidneys, adrenal glands, aorta & mediastinum. Structure: ❖ Lobules of multilocular adipocytes. ❖ Colour: brown due to rich mitochondrioa & numerous blood capillaries. Function: heatproduction.  Dense Irregular collagenous connectivetissue Site: dermis of skin. Structure: ❖ Irregular bundles of collagen type I. ❖ Fibroblasts: scattered between the bundles. ❖ Little ground substance ▪ Resistant to stress from all directions.  Dense regular collagenous connective tissue Sites: ❖ Tendons & ligaments. ❖ Corneal stroma. Structure: ❖ Parallel bundles of collagen type I. ❖ Regular Fibroblasts between the bundles. ❖ The orientation of the collagn fibers in one directions ▪ Resistant to prolonged or repeated stresses exerted in one direction  Dense regular elastic connective tissue Sites: ❖ Arteries especially the large- sized As Aorta. ❖ Ligamentum flavum. ❖ Suspensory ligament of penis. Structure: ❖ Parallel elastic fibres. ❖ Few Fibroblasts between the fibres. ❖ Little ground substance. ❖ The orientation of the elastic fibers in one directions ❖ Resistant to stresses exerted in one  MUSCULAR TISSUE 1. Sites: Skeletal Muscle ▪ All muscles attached to the skeleton. ▪ Tongue muscles. ▪ Eye muscles. ▪ Pharynx and larynx. ▪ Formed of a group of muscle fibres. ▪ Cytoplasm contains myofibrils (contractile elements Acitin and myocin). ▪ Striated: cytoplasm has regular transverse striations. ▪ Voluntary.  Organization of skeletalmuscle Fascicles are separated by dense C.T. called perimysium……(P) Each Ms fibre is enclosed by loose C.T.called endomysium (En). E:Epimysium P:Perimysium EN: Endomysium 3. Sarcomeres ▪ Z-lines: dark lines in the center of the I bands. ▪ Sarcomere begins from Z-line to Z-line. ▪ Each myofibril consists of successivesarcomeres.  Cardiac musclefibers ▪ Site: in the wall of the heart. ▪ Involuntary. 1. Number: Each fibre is formed of a chain of muscle cells linked by intercalated discs. 2. Branching and anastomosing fibers. 3. Length: variable. 4. Diameter: smaller than skeletal ms fibres. 5. Nucleus : central; one or two. 6. Cytoplasm: acidophilic with irregular striations.  Nervous tissue Cell body (perikaryon) N Nucleus: ▪ Large and spherical. ▪ Euchromatic with a prominent nucleolus (active). Pseudo unipolarneurons Bipolar neurons Two processes (axon & One process that divides dendrite) into axon & dendrite. Example: Retina and Example: Spinal ganglia olfactory epithelium.  Multipolar neurons Polygonal neurons Pyramidal neurons Pyriform neurons Eg. Sympathetic ganglia Eg. Cerebral cortex Eg. Cerebellar cortex