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 Arm Stage clips Mechanical stage 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 Slide placement Ocular lens adjustment & focusing Light adjustment Dimmer Diaphragm Substage condenser Objective lens 4X or 10X first Objective and stage close together Focusing Course adjustment - 4X or 10X only Fine adjustment Readjusting light with increasing magnification 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 (Ocular lens) X

TM = (Objective lens) x (Ocular lens)

Objective 2 : Specimen Preparation

Does this sound familiar? 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 lumen lumen

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

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 Cell that gathers information and controls body functions Macrophage Fat cell Sperm Cell that stores nutrients Cell that fights disease 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

Pluripotent Stem Cells 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

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

The study of the tissues of the body 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: Connective Tissue Epithelial Tissue Nerve Tissue Muscle 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 By number of layers Flat One layer = Simple Cubbish More then one layer = Stratified Column-like

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 Simple cuboidal Simple columnar Look for a flattened nucleus Look for a rounded nucleus Look for an oval nucleus

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

More Epithelia Pseudostratified Transitional

What to label? Nucleus Cytoplasm Basement Membrane Apical Cells Basal Cells Basement Membrane Basement Membrane

Identify the Epithelial Tissue

Identify the Epithelial Tissue

Identify the Epithelial Tissue