Week 2 Microscopic Anatomy Objective 1 The Compound

Week 2 Microscopic Anatomy

Objective 1: The Compound Light Microscope • Parts of the Microscope • Focusing Procedures • Useful Terms • Microscope Care & Handling

Parts of the Microscope Ocular lens Revolving nosepiece Objective lenses Mechanical stage Arm Stage clips Course adjustment knob Substage light Fine adjustment knob

Microscope Care & Handling • Always use both hands when transporting the microscope • Clean lenses before and after use • Never use anything but lens paper to clean lenses • Before plugging in the microscope, check to make sure all components are in proper “starting position”

Focusing Procedures 1. Slide placement 2. Ocular lens adjustment & focusing 3. Light adjustment 1. Dimmer 2. Diaphragm 3. Substage condenser 4. Objective lens 1. 4 X or 10 X first 2. Objective and stage close together 5. Focusing 1. Course adjustment - 4 X or 10 X only 2. Fine adjustment 6. Readjusting light with increasing magnification 7. Oil immersion lens

Microscope Care & Handling • Clean lenses before and after use • Never use anything but lens paper to clean lenses • Make sure you have removed the slide • Turn light OFF • Rotate the nosepiece to the lowest power objective • Position the stage & the objective lenses as close together as possible • Raise condenser lens • Switch diaphragm lever to dimmest setting • Return the microscope to it’s proper place

Total magnification is calculated by multiplying the magnification of the objective lens by the magnification of the ocular lens TM = (Objective lens) x X (Ocular lens)

TM = (Objective lens) x (Ocular lens)

Objective 2 : Specimen Preparation

Always remember: Structures, organs, and even individual cells can be sectioned in different planes. Does this sound familiar? LS WM CS

Different planes of section through the seminiferous tubules of the testes

There are several ways a specimen can be prepared for light microscopy: • Wholemount - the entire structure is mounted on the slide • Section - a thin slice of a tissue or organ is placed on a glass slide • Smear - most suitable when viewing cell suspensions such as blood, urine, mucus, cyst fluid, etc. . . • Squash - cells are broken by applying pressure to the slide, intracellular contents are liberated, e. g. , chromosomes

Whole Mount Squash Smear

Longitudinal Section Cross Section lum en en m u l

Staining The majority of specimens are stained with a combination of dyes that highlight differences between cellular structure This is an H&E stained section of the kidney. The darker blue structures are the nuclei of the cells

Some Common Stains Used in Histology or: You can’t judge a slide by it’s color Liver Hematoxylin and Eosin (H & E) Liver Iron stain

Cell structure CELL = The structural, biological, & functional unit of all living organisms

Cells come in many shapes and sizes!

Structure and function are intimately related! Erythrocytes Cells that: (a) Connect body parts (b) Form linings (c) Transport gases Fibroblasts Epithelial cells Smooth muscle cells Skeletal muscle cell Nerve cell Cells that move organs and body parts Fat cell Cell that gathers information and controls body functions Macrophage Cell that stores nutrients Cell that fights disease Sperm Cell of reproduction

Parts of a cell as seen under the microscope Nucleus Cytoplasm Plasma membrane Renal Tubule, cs

Simple squamous epithelium: two views Plasma membrane Nucleus Cytoplasm

Objective 4: Embryonic Germ Layers Pluripotent Stem Cells

The embryonic germ layers are: Ectoderm Mesoderm Endoderm

They will give rise to all the different tissues and organs of the body

Embryonic Germ Layers Section taken from a blastocyst, around the 2 nd week of development

Histology part 1 The study of the tissues of the body

TISSUE = Two or more cells that share a common: structure, function, & embryological origin

There are four tissue categories: Epithelial Tissue Muscle Tissue Connective Tissue Nerve Tissue Histology is the study of tissues.

Tissues in perspective:

Objective 1: Epithelial Tissues • Location – Covers body surfaces – Lines internal cavities Functions – Diffusion, secretion, absorption, filtration, protection Note: the singular form is epithelium; plural form epithelia

Classification of epithelium By cell shape Flat By number of layers One layer = Simple Cubbish Column-like More then one layer = Stratified

Putting it all together: To classify an epithelium state the number of layers then cell shape.

Some specializations: Cilia Microvilli

Types of Simple Epithelia Simple squamous Look for a flattened nucleus Simple cuboidal Simple columnar Look for a rounded nucleus Look for an oval nucleus

Stratified Epithelia Named according to the shape of the apical layer of cells Stratified squamous Stratified cuboidal Stratified columnar

More Epithelia Pseudostratified Transitional

What to label? Nucleus Cytoplasm Apical Cells Basement Membrane

Identify the Epithelial Tissue