Week 2 Microscopic Anatomy

Objective 1: The Compound Light Microscope Ocular lens Revolving nosepiece Objective lenses Arm Stage clips Mechanical stage Course adjustment knob Substage light Fine adjustment knob

Can you name the following parts and their function? Diagram/Self-Test                                                      Can you name the following parts and their function? How about part number: 9 3 5 1

Objective 3: Terms Relating to the Light Microscope 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)

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

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 When you are finished rotate the nosepiece to the lowest power objective Position the lens as close to the stage as possible Make sure you have removed the slide Return the microscope to it’s proper place

Objective 4: Specimen Preparation 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

Objective 2: Specimen Preparation Whole Mount Longitudinal Section Cross Section Squash Drop or Smear

Whole Mount Preparation

What might these little buggers be? A Smear Preparation What might these little buggers be?

A Squash Preparation Human Chromosomes

Staining The majority of specimens are stained with a combination of dyes that highlight differences between cellular structure This is an hematoxylin and eosin 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 Liver: Iron stain

Always remember, structures, organs, and even individual cells can be sectioned in different planes. Does this sound familiar?

Different planes of section through the seminiferous tubules of the testes

Objective 5: Structure and Function Cells come in all different shapes and sizes. Structure and function are intimately related! Sperm Cells Skeletal Muscle Cells Squamous Cells Adipose Cell

Some more examples Goblet cells in trachea Simple squamous epithelium Astrocytes, cells in the nervous system Erythrocytes

Objective 6: Embryonic Germ Layers The embryonic germ layers are ectoderm, mesoderm, and 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