12 Connective tissue proper (structure)_9bb7ef16bef7ea0e280c5f1ccd3e8ee6.pdf

Connective Tissue Part I Prepared by: Dr. Amal Abd EL-Hafez Assist. Prof. of Histopathology  Learning Objective At the end of this lecture, you will be able to: Know the definition, criteria and function of connective tissue....

Connective Tissue Part I Prepared by: Dr. Amal Abd EL-Hafez Assist. Prof. of Histopathology  Learning Objective At the end of this lecture, you will be able to: Know the definition, criteria and function of connective tissue. Outline the structure of connective tissue. Know different types of CT cells  Connective Tissue [C.T.] Definition: Tissue that connects & support cells and organs and maintains the form of the body. Origin: Mesenchyme (an embryonic tissue that develops mainly from the middle layer of the embryo, the mesoderm.  Origin of C.T. The mesenchymal cells are elongated, have many thin cytoplasmic processes, oval nucleus, fine chromatin. These cells migrate from their site of origin, to the developing organs. Mesenchymal cells give: 1. All types of connective tissue cells. 2. Blood cells. 3. Endothelial cells. 4. Muscle cells.  Functions of C.T. 1. I Providing and maintaining the shape of the body. 2. 2 Connects, binds and support the cells and organs. 3. 3 Exchange medium ( nutrients & metabolites). 4. y Special functions for adipose tissue, cartilage, bone, blood and lymphoid tissue. Connective tissue (C.T.) consists of: 1-Cells. 2-Fibers. 3-Extracellular matrix (ground substance) Structure of CT  Connective Tissue Cells These cells can be classed into 2 distinct categories: A. Resident (fixed, intrinsic) cells: 1. Stable, long lived cells, essential components of CT and present all the time. 2. Examples:: Mesenchymal cells Fibroblast Fat cells Reticular cells Pigment cells  Connective Tissue Cells B. Wandering (free, migrant) Cells: 1. Transient, wandering, short lived cells, not essential component as they belong to the immune system and reach CT at time of need. IIII 2.Example: Plasma cells Mast cells Macrophage leukocytes  1-Fibroblasts Site: all types of CT LM: 1.Elongated branched cells with many long processes. Spindle shaped in side view. Function: 2.Formation of CT fiber & ground substances. 3.Healing & repair of CT after injury  1-Fibroblasts 0  2-Macrophages: Origin: monocytes. BIENOW Sites: distributed throughout the body. LM: special stains trypan blue or India ink EM: Irregular surface with protrusions, and indentations. Kidney shaped nucleus. Well-developed Golgi complex. Prominent rough endoplasmic Reticulum. 5.Many lysosome. 6. Phagocytic vesicles  Functions: Phagocytosis. Fee Production of cytokines, chemotactic factors that participate in inflammation (defense). Antigen processing and presentation. 0 May fuse to form multinuclear giant cells. They may have different names and different functions in multiple organs e.g Kuffer cells in liver, microglia in brain and dendritic cell in skin. These cells constitute a huge group of phagocytic cells, collectively named mononuclear phagocytic system Macrophages structure and functions [phagocytosis]  3-Plasma Cell Site: lymphatic tissue LM: 1.Oval cell. side 2. Eccentric nucleus. 3. Deeply basophilic cytoplasm (excess rER) need showing negative Golgi image ( pale II unstained area of cytoplasm correspond to Golgi apparatus) Function: 4. antibody formation  4-Mast cell B se5 Site: loose CT around BV, under epithelium of GIT & resp. system 00 LM: 1. rounded to oval cells 0 0 2. Central nucleus and 3.Many basophilic granules filling cytoplasm stained metachromatically with Toluidine blue Function: secretion of: 4.Heparin 5.Histamine 6.Eosinophil chemotactic factor  6-Adipose [fat] Cells Adipose [fat] cells are of 2 types: (1) uni-locular adipocyte and (2) multi-locular adipocyte Both originate from mesenchymal precursors called lipoblasts. Milginit tumour  Uni-locular Adipocytes Site: white adipose CT LM: Large oval cell filled with single large droplet of fat (which dissolve during preparation) occupying most of the cell volume compressing cytoplasm into thin rim, pushing the nucleus to one side→ signet ring appearance Function 1.Supportive & heat insulation Around Multi-locular adipocyts organs the LM: Small rounded cells with small many fat droplets and central rounded nucleus and numerous mitochondria. Site: brown adipose CT Function: Heat generation  5-Leukocytes Discussed in blood  RECOMMENDED REFERENCES, WEBSITES Junqueira's Basic Histology: Text and Atlas, Thirteenth Edition 2013 ISBN-13: 978-0071780339 ISBN-10: 0071780335 Edition: 13th The histology tutor: http://www2.yvcc.edu/histology zoomer/HistologyTutorials/hi stology_tutorials.htm