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Dr. Nazim Nasir MD:

Dr. Nazim Nasir MD

Histology Flashback……:

Histology Flashback…… In 1665, Robert Hooke (1635-1703): Latin, cellula ; i.e., small compartment, having in mind a comparison with a honeycomb. Nucleus(Latin, nucleus = almond) by Leeuwenhoek , in 1700, when examining the red blood cells of the salmon. Max Schultze (1861): Cell is a small mass of nucleated protoplasm. Nuclear envelope by Jan Evangelista Purkinje (1787-1869). Purkinje also introduced in Science the term protoplasma (1840). Term nucleus in microscopy by Robert Brown (1773-1858).

Slide 3:

Rudolf Virchow (1821-1902): Omnis cellula e cellula ; that is, each cell comes from another cell (1858). Marie François Bichat (1771-1802): “ tissu ” (i.e., a body component): THE FIRST HISTOLOGIST Marcello Malpighi (1628-1694): “Father of Histology”. A. Mayer created the term Histology. Greek root words ( histos = tissue and logos = study). Sir Richard Owen (1804-1892): recommended for large usage term histos . Rudolph von Kölliker (1817-1905): Handbuch der Gewebelehre (i.e., The book for teaching tissues), published in 1852; so, some authors considered him the true founder of Histology.

Cell Organelles:

Cell Organelles Organelle = “little organ” Found only inside eukaryotic cells All the stuff in between the organelles is cytosol Everything in a cell except the nucleus is cytoplasm

Cell Membrane:

Cell Membrane Boundary of the cell Made of a phospho lipid bi layer


Nucleus Control center of the cell Contains DNA Surrounded by a double membrane Usually the easiest organelle to see under a microscope Usually one per cell


Cytoskeleton Acts as skeleton and muscle Provides shape and structure Helps move organelles around the cell Made of three types of filaments

Endoplasmic Reticulum:

Endoplasmic Reticulum A.k.a. “ER” Connected to nuclear membrane Highway of the cell Rough ER : studded with ribosomes; it makes proteins Smooth ER : no ribosomes; it makes lipids


Ribosome Site of protein synthesis Found attached to rough ER or floating free in cytosol Produced in a part of the nucleus called the nucleolus That looks familiar…what is a polypeptide ?

Golgi Apparatus:

Golgi Apparatus Looks like a stack of plates Stores, modifies and packages proteins Molecules transported to and from the Golgi by means of vesicles


Lysosomes Garbage disposal of the cell Contain digestive enzymes that break down wastes Which organelles do lysosomes work with?


Mitochondria “Powerhouse of the cell” Cellular respiration occurs here to release energy for the cell to use Bound by a double membrane Has its own strand of DNA


Chloroplast Found only in plant cells Contains the green pigment chlorophyll Site of food ( glucose ) production Bound by a double membrane

Cell Wall:

Cell Wall Found in plant and bacterial cells Rigid, protective barrier Located outside of the cell membrane Made of cellulose ( fiber )


Vacuoles Large central vacuole usually in plant cells Many smaller vacuoles in animal cells Storage container for water, food, enzymes , wastes, pigments, etc. What type of microscope may have been used to take this picture?


Centriole Aids in cell division Usually found only in animal cells Made of microtubules Where else have we talked about microtubules ?

Quick Review:

Quick Review Which organelle is the control center of the cell? Nucleus Which organelle holds the cell together? Cell membrane Which organelles are not found in animal cells? Cell wall, central vacuole, chloroplasts Which organelle helps plant cells make food? Chloroplasts What does E.R. stand for? Endoplasmic reticulum

The Microscope:

The Microscope

The History:

The History Many people experimented with making microscopes Was the microscope originally made by accident? (Most people were creating telescopes) The first microscope was 6 feet long!!! The Greeks & Romans used “lenses” to magnify objects over 1000 years ago.

The History:

The History Hans and Zacharias Janssen of Holland in the 1590’s created the “first” compound microscope Anthony van Leeuwenhoek and Robert Hooke (1635-1703) made improvements by working on the lenses Anthony van Leeuwenhoek 1632-1723 Robert Hooke 1635-1703 Hooke Microscope

The History:

The History Zacharias Jansen 1588-1631 The “First” Microscope

How a Microscope Works:

How a Microscope Works Convex Lenses are curved glass used to make microscopes (and glasses etc.) Convex Lenses bend light and focus it in one spot.

How a Microscope Works:

How a Microscope Works Ocular Lens (Magnifies Image) Objective Lens (Gathers Light, Magnifies And Focuses Image Inside Body Tube) Body Tube (Image Focuses) Bending Light : The objective (bottom) convex lens magnifies and focuses (bends) the image inside the body tube and the ocular convex (top) lens of a microscope magnifies it (again).

The Parts of a Microscope:

The Parts of a Microscope

Slide 25:

Body Tube Nose Piece Objective Lenses Stage Clips Diaphragm Light Source Ocular Lens Arm Stage Coarse Adj . Fine Adjustment Base Skip to Magnification Section

Body Tube:

Body Tube The body tube holds the objective lenses and the ocular lens at the proper distance Diagram

Nose Piece:

Nose Piece The Nose Piece holds the objective lenses and can be turned to increase the magnification Diagram

Objective Lenses:

Objective Lenses The Objective Lenses increase magnification (usually from 10x to 40x) Diagram

Stage Clips:

Stage Clips These 2 clips hold the slide/specimen in place on the stage. Diagram


Diaphragm The Diaphragm controls the amount of light on the slide/specimen Turn to let more light in or to make dimmer. Diagram

Light Source:

Light Source Projects light upwards through the diaphragm, the specimen and the lenses Some have lights, others have mirrors where you must move the mirror to reflect light Diagram

Ocular Lens/Eyepiece:

Ocular Lens/Eyepiece Magnifies the specimen image Diagram


Arm Used to support the microscope when carried. Holds the body tube, nose piece and objective lenses Diagram


Stage Supports the slide/specimen Diagram

Coarse Adjustment Knob:

Coarse Adjustment Knob Moves the stage up and down (quickly) for focusing your image Diagram

Fine Adjustment Knob:

Fine Adjustment Knob This knob moves the stage SLIGHTLY to sharpen the image Diagram


Base Supports the microscope Diagram




Magnification To determine your magnification…you just multiply the ocular lens by the objective lens Ocular 10x Objective 40x:10 x 40 = 400 Objective Lens have their magnification written on them. Ocular lenses usually magnifies by 10x So the object is 400 times “larger”

Caring for a Microscope:

Caring for a Microscope Clean only with a soft cloth/tissue Make sure it’s on a flat surface Don’t bang it Carry it with 2 HANDS…one on the arm and the other on the base

Carry a Microscope Correctly:

Carry a Microscope Correctly

Using a Microscope:

Using a Microscope Start on the lowest magnification Don’t use the coarse adjustment knob on high magnification…you’ll break the slide!!! Place slide on stage and lock clips Adjust light source (if it’s a mirror…don’t stand in front of it!) Use fine adjustment to focus

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