1. Connective Tissue Maarefa College

2. Objectives What is connective tissue Types of connective tissues Functions of connective tissues – Relation of structure and function

3. Tissues Four fundamental tissues are recognized: – Epithelial tissue – Connective tissue – Muscular tissue – Nervous tissue

4. Connective Tissue Consists of two basic elements: – Cells, and – Extra-cellular matrix (abundant) (dominant part) Fibers, and Ground substance – liquid, gel, or solid Function – Bind and/or support other tissue

5. Connective Tissue Consists of two basic elements: – Cells, and – Extra-cellular matrix (abundant) (dominant part) Fibers, and Ground substance – liquid, gel, or solid Function – Bind and/or support other tissue

6. Connective Tissue Cells Fibroblasts: – Secrete both fibers and ground substance of the matrix (wandering) Macrophages: – Phagocytes that develop from Monocytes (wandering or fixed) Plasma Cells: – Antibody secreting cells that develop from B- Lymphocytes (wandering)

7. Connective Tissue Cells Mast Cells – Produce histamine that help dilate small blood vessels in reaction to injury (wandering) Adipocytes: – Fat cells that store triglycerides, support, protect and insulate (fixed)

8. Connective Tissue Cells

9. Matrix Fibers Collagen Fibers Elastic Fibers Reticular Fibers

10. Matrix Fibers Collagen Fibers: – Large fibers made of the protein collagen – The most abundant fibers – Promote tissue flexibility

11. Matrix Fibers Elastic Fibers: – Intermediate fibers made of the protein Elastin – Branching fibers that allow for stretch and recoil Polarizing microscopy picrosirius-stained collagen, elastic fibers are stained by orcein

12. Matrix Fibers Reticular Fibers: – Small delicate, branched fibers – Have same chemical composition of Collagen – Forms structural framework for organs such as spleen and lymph nodes.

13. Matrix Fibers

14. Collagen Elastin

15. Elastic and Collagen Fibers

16. Fibroblasts Active fibroblasts have extensions Extensions of fibroblasts (arrow-heads) are seen with the cell or alone, depending on section plane

17. Fibroblasts Active fibroblasts have extensions Electron micrograph of fibrocyte with cytoplasmic extensions interdigitating among collagen fibers, X 26,000

18. Matrix Ground Substance Hyaluronic Acid: – Complex combination of polysaccharides and proteins found in “true” or proper connective tissue Chondriotin sulfate: – Jellylike ground substance of cartilage, bone, skin and blood vessels Other ground Substances: – Dermatin sulfate, keratin sulfate, and adhesion proteins

19. Types of Connective Tissue 1.True (Proper) Connective Tissue – Loose Connective Tissue – Dense Connective Tissue 2.Supportive Connective Tissue – Cartilage – Bone 3.Liquid Connective Tissue – Blood

20. True or Proper Connective Tissue Loose Connective Tissue: – Areolar tissue Widely distributed under epithelia – Adipose tissue Hypodermis, within abdomen, breasts – Reticular connective tissue Lymphoid organs such as lymph nodes

21. Loose Connective Tissue Areolar CT – consists of all 3 types of fibers, several types of cells, and semi-fluid ground substance – found in subcutaneous layer and mucous membranes, and around blood vessels, nerves and organs – function = strength, support and elasticity

22. Loose Connective Tissue Areolar CT

23. Loose Connective Tissue: Adipose tissue – consists of adipocytes; "signet ring" appearing fat cells. They store energy in the form of triglycerides (lipids) – found in subcutaneous layer, around organs and in the yellow marrow of long bones – function = supports, protects and insulates, and serves as an energy reserve

24. Loose Connective Tissue: Adipose tissue

25. Loose Connective Tissue Adipose tissue

27. Loose Connective Tissue Reticular CT – Consists of fine interlacing reticular fibers and reticular cells – Found in liver, spleen and lymph nodes – Function = forms the framework (stroma) of organs and binds together smooth muscle tissue cells

28. Loose Connective Tissue Reticular CT

29. Loose Connective Tissue Reticular CT

30. Loose Connective Tissue Reticular CT

31. Loose Connective Tissue Reticular CT

32. True (Proper) Connective Tissue Contains more numerous and thicker fibers and far fewer cells than loose CT Dense Connective Tissue: – Dense regular connective tissue Tendons and ligaments – Dense irregular connective tissue Dermis of skin, submucosa of digestive tract

33. True (Proper) Connective Tissue Dense regular Connective Tissue – consists of bundles of collagen fibers and fibroblasts – forms tendons, ligaments and aponeuroses – Function = provide strong attachment between various structures

34. True (Proper) Connective Tissue Dense regular Connective Tissue

35. True (Proper) Connective Tissue Dense regular Connective Tissue

36. True (Proper) Connective Tissue Dense regular Connective Tissue (Tendon)

37. True (Proper) Connective Tissue Dense Irregular CT – Consists of randomly-arranged collagen fibers and a few fibroblasts – Found in fasciae, dermis of skin, joint capsules, and heart valves – Function = provides strength

38. True (Proper) Connective Tissue Dense Irregular CT

39. Supportive Connective Tissue: Cartilage: – Jelly-like matrix (chondroitin sulfate) containing collagen and elastic fibers and chondrocytes surrounded by a membrane called the perichondrium – Unlike other CT, cartilage has NO blood vessels or nerves except in the perichondrium – Collagen fibers provide strength – chondroitin sulfate provides resilience – Chondrocytes occur within spaces in the matrix called lacunae.

40. Supportive Connective Tissue Cartilage: – Hyaline cartilage – Fibro-cartilage – Elastic cartilage

41. Supportive Connective Tissue Hyaline Cartilage (most abundant type) – Fine collagen fibers embedded in a gel-type matrix – Occasional chondrocytes inside lacunae. – Found in: embryonic skeleton, at the ends of long bones (joints), in the nose and in respiratory structures – Function= flexible, provides support, allows movement at joints

42. Supportive Connective Tissue Hyaline Cartilage (most abundant type)

43. Supportive Connective Tissue Hyaline Cartilage (most abundant type)

44. Supportive Connective Tissue Hyaline Cartilage (most abundant type) Perichondrium Hayaline Cartilage

45. Supportive Connective Tissue Hyaline Cartilage (most abundant type) – Covers articular surfaces

46. Supportive Connective Tissue Fibrocartilage – contains bundles of collagen in the matrix that are usually more visible under microscopy – Found in: Intervertebral discs, Menisci of the knee, Pubic Symphysis, Tendon insertion on apophyseal hyaline cartilage – Function: Support and fusion, shock absorption

47. Supportive Connective Tissue Fibrocartilage

48. Supportive Connective Tissue Fibrocartilage

49. Supportive Connective Tissue Fibrocartilage

50. Supportive Connective Tissue Fibrocartilage Picrosirius-Hematoxilin stain of fibrocartilage, with abundant collagen fibers

51. Supportive Connective Tissue Elastic Cartilage – Threadlike network of elastic fibers within the matrix – Found in: external ear, auditory tubes, epiglottis – function = gives support, maintains shape, allows flexibility

52. Supportive Connective Tissue Elastic Cartilage

53. Supportive Connective Tissue Elastic Cartilage

54. Supportive Connective Tissue Elastic Cartilage Resorcin stain selectively staining the elastic fibers of elastic cartilage tissue Cells are not stained

55. Supportive Connective Tissue Bone – The hardest CT – Osteocytes in small cavities- lacunae – Impregnated w/ calcium salts – Types: Spongy (cancellous) – Loose rods of bones – Found inside body of long bones, and ends of arms and legs Compact (cortical) – Tightly organized – Found inshafts of long bones

56. Supportive Connective Tissue Bone Types: – Spongy (cancellous) Loose rods of bones Found inside body of bones, and ends of arms and legs – Compact (cortical) Tightly organized Found in shafts of long bones

57. Supportive Connective Tissue Bone

58. Supportive Connective Tissue Bone

59. Supportive Connective Tissue Bone Section of a Haversian system (Osteone)

60. Supportive Connective Tissue Bone cells – Osteoclasts: resorb (eat) bone

61. Supportive Connective Tissue Bone cells – Osteoclasts: resorb (eat) bone – Osteoblasts: build bone – Osteocytes: osteoblasts surrounded by matrix they formed

62. Supportive Connective Tissue Bone cells – Osteoclasts: resorb (eat) bone – Osteoblasts: build bone – Osteocytes: mature osteoblasts surrounded by matrix that it formed

63. Liquid Connective Tissue Blood

64. Liquid Connective Tissue Lymph

65. Summary What is connective tissue Structure: Consists of two basic elements: – Cells, and – Extra-cellular matrix (abundant) (dominant part) Fibers, and Ground substance (liquid, gel, or solid) Function – Binds and/or supports other tissue

66. Summary 1.True (Proper) Connective Tissue – Loose CT (aereolar, adipose, reticular) – Dense CT (regular, irregular) 2.Supportive Connective Tissue – Cartilage – Bone 3.Liquid Connective Tissue – Blood – Lymph Types of Connective Tissue: