1. بسم الله الرحمن الرحيم

2. INTRODUCTION TO HISTOLOGY

3. HISTOLOGY (MICROSCOPIC ANATOMY) Definition.

4. Basic Histological Techniques (A) Light Microscopy: 1- Fixation: e.g. Formalin. 2- Dehydration: Ethanol. 3- Clearing: e.g. Xylene. 4- Embedding: e.g. Paraffin. 5- Sectioning: Microtome. 6- Staining: e.g. H&E (Hematoxylin& eosin). Acidophilic and basophilic structures. e.g. Metachromatic staining ( Toluidine blue).

5. Microtome

6. Light Microscope (L/M) 1- Illumination. 2- Magnification. 3- Resolution. N.B. Resolving power ( It is the least distance between 2 particles at which they will appear separated). R.P. for L/M is 250 nm

7. Light microscope

8. (B) Electron microscopy: 1-Transmission E/M: Resolving power 0.2 nm. * Electron-dense structure **Electron-lucent structure 2-Scanning E/M: Resolving power 10 nm.

9. Transmission Electron Microscope

10. Scanning Electron microscope

11. THE CELL

12. THE CELL NUCLEUS (INTERPHASE NUCLEUS)

13. Shape of nuclei

14. Dark Nucleus (Deeply-stained nucleus)

16. Vesicular(open face) Nucleus

18. L/M: Appearance (Type): - Light nucleus (vesicular) (open face) - Dark nucleus (deeply-stained) (dense Nucleus) Number: 1, 2, or more. Position: Central, eccentric, peripheral, basal. CELL NUCLEUS (Interphase Nucleus)

19. Cell Nucleus L/M: Size: Small, medium, large ( Nucleus/cell ratio) Shape: e.g. Rounded, oval, rod-shaped.

20. Nucleus (E/M diagram)

21. Nucleus (Electron Micrograph) PRACTICAL

22. Nuclear pores

23. Cell Nucleus (Interphase nucleus) E/M: (1) Nuclear envelope Inner nuclear membrane. Outer " ". Nuclear pores. Nuclear pore complex. Perinuclear cisterna. Nuclear lamina. N.B.Rough Endoplasmic reticula.

24. (2) Chromatin: ( Classification ): According to Metabolic activity: a- Euchromatin(Extended chromatin) b- Heterochromatin( Condensed chrom. ) According to Position: a- Peripheral chromatin. b- Nucleolus-associated chromatin. c- Chromatin islands.

25. Nucleolus (E/M)

26. (3) Nucleolus: L/M: 1-5 basophilic bodies E/M: 1- Pale-staining fibrillar center: Nucleolar organizer DNA** + Inactive DNA N.B. ** are found in the tips of chromosomes 13,14,15,21&22 with genes that encode rRNA. 2- Pars fibrosa: containing rRNA (nRNA) being transcribed.

27. Nucleolus (cont.): 3- Pars granulosa: maturing ribosomal subunits are assembled. 4- Nucleolar matrix: a network of fibers active in nucleolar organization. N.B. Nucleolus is a non-membranous structure. Function of nucleolus: rRNA synthesis.

28. NUCLEOPLASM 1- Nuclear matrix. 2- Ribonucleoprotein. 3- Interchromatin granules. 4- Perichromatin granules.

30. APOPTOSIS Definition: Genetic programmed cell death. Mechanism: Caspases : enzymes coded by highly conserved genes. Caspases are activated by cytokines e.g. TNF. This triggers a cascade of caspases. Degradation of chromosomes, Nuclear lamins & cytoskeletal proteins. The entire cell becomes fragmented. The cell fragments are then phagocytosed by macrophages.

31. PRACTICAL SESSION Electron Micrographs

32. Nucleus (Electron Micrograph)

33. Nucleolus (E/M)

34. Nuclear pores

35. BEST WISHES

36. CYTOPLASM (1)Organelles. (2)Cytoskeleton. (3)Inclusions. (4)Cytosol.

37. Cytoplasmic organelles 1- Cell Membrane. 2- Ribosomes. 3- Endoplasmic Reticulum. 4- Golgi Apparatus. 5- Lysosomes. 6- Peroxisomes. 7- Proteasomes. 8- Mitochondria 9- Annulate lamella.

38. Cytoskeleton 1- Thin Filaments. 2- Intermediate Filaments. 3- Microtubules.

39. Cell Surface Specializations 1- Microvilli. 2- Cilia.

40. Cytoplasmic Inclusions 1- Glycogen. 2- Lipids. 3- Pigments. 4- Crystals.

41. Cell Membrane (Plasmalemma)

42. CELL MEMBRANE & GLYCOCALYX

46. ENDOSOMES

47. MITOCHONDRIA

49. ENDOPLASMIC RETICULUM

50. ROUGH ER

51. RER & SECRETORY GRANULES

52. POLYSOMES (POLYRIBOSOMES)

53. GOLGI APPARATUS

59. CILIA

60. CILIA & CENTRIOLES

63. Glycogen granules in hepatocyte