STUDY OF ELECTRON MICROGRAPHS OF DIFFERENT COMPONENTS OF ANIMAL CELL

1. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR)

2. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) Some what similar to a Light Microscope (LM) 1) Electron gun produces electron beam and magnetic lenses, stacked vertically to form a lens column 2) Illumination system the electron gun, and 2 or more condenser lenses 3) Specimen stage assemble/remove the specimen; hold/move specimen 4) Imaging system three lenses that together produce a magnified image on the monitor screen

4. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) TEM images are always monochromatic / gray scale (black and white) false colors may be added to the images with image processing software

6. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) Primary Fixation: Glutaraldehyde 2.5% + 2-4% Paraformaldehyde Secondary Fixation: Osmium tetroxide, electron dense, fixative and a stain Dehydration: in acetone or ethanol Infiltration: with resins Embedding: Epoxy resin Sectioning: • Semi-thin sections (0.5-1.0 um) stained with toluidine blue for selection of the target areas • Ultrathin sections (60-90 nm) are cut and collected onto grids air dried for 2 h – overnight Staining: uranyl acetate or lead citrate

8. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR)  Cell Membrane • low/medium magnification, appears as an electrondense line • high magnification, appears a bilayer • 7 to 11 nm thick membrane • called trilaminar membrane, has three visible lines • two electron dense lines separated by one electron translucent line • because the lines are parallel, it is called ‘railroad track”.

10. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) • spherical or cupshaped, rod shaped or irregular • an outer, and an inner mitochondrial membranes parallel to the outer membrane o Inner membrane continues to form the cristae • mitochondrial (dense bodies) matrix is internal called matrix granules that are calcium salts • lamellar (sheet-like) or tubular; branching and anastomosing cristae may be observed

14. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) • part of the flattended endo-membranous components (cristae) • found in the cytoplasm and are studded with ribosomes • Ribosomes are seen on the external surface • cisternae are interconnected, the lumen is dense • occassionally, seen in continuity with nuclear envelope • The rER and smooth endoplasmic reticulum (sER) are commonly found to be continuous

18. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) • no ribosomes • composed of anastomosing tubules (100 nm dia.) • irregular shape and diameter • appears as a ''contorted" network of smooth membranous elements • tubules form a continuous membrane system that weaves in and out of the plane of section

21. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) • appears as a group of stack membrane cisternae (Golgi stack or dictyosome) • cisternae form a slightly curved or U shaped structure • generally located near the nucleus • stacks contain a number of cisternae, less than ten • convex face: forming or cis face • concave face is known as the maturing or trans face • vacuoles containing dense material seen near the trans face

25. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) • Peroxisomes (microbodies) displays a finely granular matrix • lysosome is more densely granular and contain ingested material

26. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) • short, cylindrical structures seen in pairs called diplosomes • near the nucleus close by the Golgi apparatus • composed of microtubular elements, fused as triplets. Nine sets of triplets are arranged in a ‘pinwheel fashion’.

29. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) • spherical, ellipsoidal, flattened, lobed, or highly infolded • Nuclear features include the nuclear envelope, the nuclear lamina, and the nucleolus

30. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR)  Nuclear envelope present in eukaryotes • a double membrane: outer and inner membranes that encompass the nucleoplasm • space between the two membranes is called the perinuclear space • rER is often in direct continuity with the nuclear envelope • at intervals, the two membranes participate in forming nuclear pores  Nuclear lamina: a uniform layer of dense material along the inner aspect of the nuclear envelope

32. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR)  Heterochromatin condensed or visible chromatin, is stable (inactive)  Euchromatin uncondensed form of chromatin are relatively clear areas of the nuclear matrix; 10% available for transcription

34. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) Thanks ..!

35. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) The Glycocalyx • fuzzy coat external to plasma membrane seen in EM • difficult to visualize; special stains are used to observe • many times thicker than plasma membrane • Polysaccharide in nature • part of intrinsic proteins of plasmalemma • found in tubular organs; extends to lumen • negatively charged

38. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) • linear fusions of membrane between adjoining epithelial cells • usually extend around the entire circumference • appears as a five layered or pentalaminar at junction site

41. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) • 2 types Intermediate junction or zonula adherens • forms a continuous "belt" around the cell • the intercellular space remains constant at junctional site • a vague intercellular line parallel to junctional membranes • cytoplasmic surface has a density receives actin filaments

43. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) Desmosome or macula adherens • plaque like structures • contains a definite intermediate dense line in intercellular space parallel to cell surface • Intermediate filaments of keratin (tonofilaments) make hairpin turns at the junctional density • Freeze fracture reveals them as aggregations of intramembranous particles of unequal size

49. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) Hemidesmosomes or half desmosomes • cell surface specializations • found at interface b/w epithelium and the underlying basal lamina • appearance at the cell surface is one whereby the junction resembles a desmosome joined to a basal lamina.

52. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) • demonstrate a sevenlayered (septalaminar) appearance • the opposing membranes of the cells come close to each other, but do not fuse • intercellular space 2 to 4 nm • Gap junction particles (connexins) are seen in thin sections • work in intercellular communication • Connexins contain pores that transport molecules of 1,200 kd molecular weight

59. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) • join all epithelial cells at their lateral surface near the apical aspect of the cell • present where the lateral surface of the epithelial cell meets a lumen; e.g. in the gastrointestinal tract • The tight junction is the component closest to the lumen • followed by the intermediate junction, and then the hemi- desmosome, which is most basally positioned • desmosomes are only periodic structures

66. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) 1. Vacuum system 2. Electron beam generation system 3. Electron beam manipulation system 4. Beam specimen interaction system 5. Detection system 6. Signal processing and display system

68. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) 1. Vacuum system: Prevents air electron collisions 2. Electron beam generation system: Electron gun 3. Electron beam manipulation system: electromagnetic lenses and coils- control the size, shape, and position of the electron beam on the specimen surface 4. Beam specimen interaction system: Electron beam and specimen interaction 5. Detection system: A secondary electron detector 6. Signal processing and display system: visualization of an electronic signal

69. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) As the beam passes through the final condenser lens, two sets of magnetic scanning coils move the beam:  These radially opposing, magnetic coils allow scanning in both the X and Y directions  The scan pattern is called a raster (rectangular) pattern  The scan begins in the upper left corner and proceeds to the right, then dropping down one line with each line scanned  these coils give the scanning electron microscope its name

72. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) • Each point on the specimen that is struck by the accelerated electrons emits signal in the form of electromagnetic radiation • Selected portions of this radiation, usually secondary (SE) and/or backscattered electrons (BSE), are collected by a detector • the resulting signal is amplified and displayed on a TV screen or computer monitor

87. DR. JAMEEL AHMED GANDAHI, PhD ASSISTANT PROFESSOR DEPARTMENT OF ANATOMY & HISTOLOGY SINDH AGICULTURE UNIVERSITY TANDOJAM General Histology & Embryology ANAT-103 (PR) SEM TEM  Resolving power 400 pm  based on scattered electrons  Reports morphology and relation  large area of sample analyzed at a time  Projects picture via CRT to monitor  3D  Resolving power 50 pm  based on transmitted electrons  Reports internal composition  only small area of sample analyzed at a time  fluorescent screens / monitor  2D

STUDY OF ELECTRON MICROGRAPHS OF DIFFERENT COMPONENTS OF ANIMAL CELL

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