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 Revolving Substage light

Can you name the following parts and their function? e h t n o s i h t ee al s o ctic t t c a e r p P Ex

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”

“Starting Position” of Microscope 1. On/Off switch OFF 2. Objective lenses Rotated such that 4 X lens (shortest) is facing down 3. Stage and Objective lenses as close together as possible (lenses lowered or stage raised) 4. Substage condenser lens in raised position 5. Iris diaphragm turned to dimmest setting

Focusing Procedures 1. Slide placement 2. Ocular lens adjustment & focusing 3. Light adjustment 1. Dimmer 2. Diaphragm 3. Substage condenser 4. Objective lens rules 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 rules

Microscope Care & Handling When finished • 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 (Ocular lens) X 4 X 10 X 40 X 10 X

TM = (Objective lens) x (Ocular lens)

Try these: The total magnification of this Ə is 40 X. The magnification of the ocular lens is 10 X. Which objective lens was used? The total magnification of this Ə is 400 X. Which objective lens was used?

NOTE: • Total Magnification included in score • Don’t forget the “X” symbol TM = 400 X

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

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

Different planes of section through the seminiferous tubules of the testes

Cross Section Lumen

Cross Section en m u L Lumen

Whole Mount Squash Smear

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 See Lab Manual Appendix

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

Several steps are used to make a section Fixation: a specimen is treated with a chemical solution to: (1) prevent bacterial action and self destruction by cellular enzymes (2) ensure preservation and hardening

Dehydration and Embedding In order for the tissue to be sectioned, it must be “supported” to ensure accurate cutting. Paraffin wax is often used for this purpose, using the following procedure: – dehydration of the tissue by passing it through a series of alcohol/water mixtures, since wax won’t mix with the water naturally found in the tissue – clearing, which removes the alcohol – transfer into molten wax inside an embedding oven Dehydration Embedding

Sectioning • • • a microtome is used to slice the embedded tissue into thin slices (1 -150 micrometers thick) the cut sections are then floated onto a water covered slide to remove any creasing the slides are then drained and placed over a gentle heat to dry off the water and ensure that the tissue adheres to the slide

Objective 3: Generalized Mammalian Cell

Identifying cells and their parts (Simple columnar) (Osteocyte) (Adipocyte)

Parts of a cell Plasma Membrane

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

Objectives 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

LAB 3: HISTOLOGY Head Start b/c you will be drawing 19 slides

TISSUE = Two or more cells that share a common: structure, function, & embryological origin Tissue composed entirely of cells that covers or lines is called EPITHELIAL TISSUE

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

Find the epithelia:

Classification of epithelium By cell shape Flat (Squashed) By number of layers One layer = Simple Squamous Cubish Cuboidal Column-like Columnar More then one layer = Stratified

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

Knowing the function and location of each tissue type will help you make sense of them and aid in memorization.

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

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

Other Epithelia Pseudostratified columnar Transitional Cells have a tapered appearance Large cells w/ Large round nuclei “plumpy” appearance Apical cells larger than basal cells

More than one tissue type can be found in the same image: Longitudinal Section lum en en m u l Cross Section

Some specializations: Cilia Microvilli

Epithelial tissue is connected to the underlying (connective) tissue via an extracellular matrix called basement membrane

What to label? Nucleus Cytoplasm Apical Cells Basement Membrane

What to label?