HISTOLOGY Lecture TWO DR. ASHRAF SAID

Transcription

1 HISTOLOGY Lecture TWO DR. ASHRAF SAID

2 Start Of this lecture

3 TISSUES

4 TISSUE: A DEFINITION A group of connected and interdependent cells that cooperate to perform a specific function

5 CONNECTIVE TISSUE The Major Structural Constituents of The Body

6 Categories of Tissue 1. Epithelial Tissue 2. Connective Tissue 3. Muscle Tissue 4. Nervous Tissue

7 Function of CT Responsible for: providing & maintaining form in the body. Provide a matrix that connects and binds: cells & organs and ultimately supports body.

8 Components of CT Cells Extracellular matrix Fibers Collagenous, reticular, elastic Ground substance Hydrophilic macromolecules (glycoproteins, glycosaminoglycans, proteogycans) bind to receptors on cells & add strength and rigidity to matrix

9 Origins of CT Mesenchyme Embryonic undifferentiated tissue Develops from mesoderm Cells migrate from origins penetrate & surround organs Develop into other types of structures: blood cells Muscles bones

10 Embryonic Mesenchyme

11 CT Cells Fibroblasts Differentiate from mesenchyme Remain local Synthesis of all fibers Synthesis of all ground substance. Mast cells* Contain granules with: Histamine Heparin Leukotrienes. Macrophages* (histiocytes) Phagocytosis Plasma cells* Derived from lymphocytes Produce antibodies. * Originate from hematopoietic stem cells in bone marrow, circulate in blood, move to CT where they remain and perform their functions

12 Fibroblasts (inactive) Synthesize collagen, elastin and macromolecules of ground substance. Rarely undergo division.

13 Macrophages Characterized by phagocytic ability Morphological features correspond to activity they inhabit. to tissue they inhabit. Derived from bone marrow cells (monocytes): that circulate in blood Mature leave vessels & enter organs. Long-living cells (months) Become Kupffer cells in liver Microglial cells in CNS Osteoclasts in bone.

14 Mast Cells Function storage of chemical mediators of the inflammatory response. Contain many secretory granules. Release histamine Release heparin Release leukotrienes Receptors on cell surface allow binding of IgE

15 Mast cells

16 Extracellular matrix Fibers Ground substance

17 Fibers Collagenous Reticular Elastic

18 Collagenous Fibers Collagenous Most common protein in the body (30% of dry weight) Stain pink with eosin Stain blue with Mallory s trichrome Stain green with Masson s trichrome Make up: mesenteries Tendons Cartilage Ligaments lamina propria Every organ.

19 Collagenous Fibers (Dense Irregular CT)

20 Reticular Fibers Reticular Are not stained by H&E Stain black with silver Very delicate Hold cells together in organs. Provide framework for: Spleen Lymph nodes Red bone marrow Liver, Endocrine glands. Makes flexible network in: Arteries Intestinal muscle layer Uterus

21 Reticular CT (Adrenal Cortex)

22 Reticular Fibers

23 Reticular CT

24 Elastic Fibers Stretchable, highly resistant to pulling forces. Found in arteries, cartilage, mesenteries

25 Collagen, Elastic Fibers (Areolar CT)

26 Extracellular Matrix Fibers Collagenous (collagen) Reticular (collagen) Elastic (elastin) Amorphous ground substance Gel-like matrix in which fibers, cells are embedded and through which fluid diffuses. Tissue fluid

27 ADULT CT CT proper Loose Reticular Adipose Dense irregular Dense regular Collagenous Elastic Specialized CT Cartilage Bone Blood

28 Loose (Areolar) Conn Tissue Structure Many cells Jello-like matrix Collagen + elastic fibers

29 Binding Tissue Function: Binds organ parts together Sample Locations: Skin, kidney, lungs

30 Loose CT

31 Elastic, Reticular Fibers

32 Dense Irregular CT

33 Dense Irregular CT

34 Section of rat skin. The subepithelial connective tissue (dermis) is loose connective tissue. In this area, the cells, most of which are fibroblasts, are abundant. The deepest part of the dermis consists of dense irregular connective tissue, which contains many randomly oriented thick collagen fibers, scarce ground substance, and few cells. H&E stain. Medium magnification. (Courtesy of TMT Zorn.)

35 Elastic Connective Tissue

36 Dense Regular C T Structure Few cells Dense matrix Aligned collagen fibers

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38 DENSE CT

39 Tendons

40 E-P-M

41 Elastic, Reticular Fibers

42 CT

43 Dense Irregular CT

44 Epididymis Pseudostratified microvilli

45 ELASTIC CARTILAGE

46 Loose CT

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