4-1-6-blood-cells

Drawing Cells From Blood Smears

• To record the observations seen under the microscope (or from photomicrographs taken) a labelled biological drawing is often made

• Biological drawings are line pictures which show specific features that have been observed when the specimen was viewed

• There are a number of rules/conventions that are followed when making a biological drawing

• The conventions are:

  • The drawing must have a title

  • The magnification under which the observations shown by the drawing are made must be recorded

  • A sharp HB pencil should be used (and a good eraser!)

  • Drawings should be on plain white paper

  • Lines should be clear, single lines (no thick shading)

  • No shading

  • The drawing should take up as much of the space on the page as possible

  • Well-defined structures should be drawn

  • The drawing should be made with proper proportions

  • Label lines should not cross or have arrowheads and should connect directly to the part of the drawing being labelled

  • Label lines should be kept to one side of the drawing (in parallel to the top of the page) and drawn with a ruler

• Drawings of cells are typically made when visualizing cells at a higher magnification power, whereas plan drawings are typically made of tissues viewed under lower magnifications (individual cells are never drawn in a plan diagram)

Blood smears

• A blood smear is when a small amount of blood is spread on a glass microscope slide, stained and covered with a coverslip

• The different blood cells can then be examined using a microscope

  • Red blood cells have no nuclei and a distinct biconcave shape

  • White blood cells have irregular shapes

  • Neutrophils have distinctive lobed nuclei

    • They make up roughly 70% of all white blood cells

  • Lymphocytes have very large nuclei that nearly occupy the entire cell

The different blood cells present in a blood smear

The lobed nucleus of a neutrophil

An example of blood cells drawn from the field of view of a microscope observing a blood smear