Section Terms

In Biology, as in Real Life, when we want to look at the inside of something, we usually have to cut it open.  When one person learns the inside "parts" of something and wants to teach someone else, they often draw a representation and label the parts, and that is how they communicate the names of the parts to someone else.

For instance, if you want to know the parts inside an apple:

You can find a figure of the apple cut open, with the parts labeled.  Since we are all familiar with what an apple looks like on the outside, the cross-section image makes sense to us, and we can learn the names of the parts.

This week in lecture and lab we are learning about the terminology related to planes of section.  This is a figure from another lab manual that helps to correlate some of the terms, and how they would affect a slice of a structure on a slide.

Next week we are going to start learning how to use the microscope to look at slices of tissue.  We will need to use some of the information learned about sections and apply it to microscopic images. This can be a confusing step sometimes - we understand from experience what an apple looks like, but we don't always have a good idea what a "duct" or a "gland" looks like.

So we use artists drawings of the three-dimensional structure to try to understand what we are looking at a slice of under the microscope.

We will take time in lab to understand more about the microscope slides we are studying.  The first step, though, is thinking about the planes of section and learning the terms.  Good luck!

Red, White, and .... yes, Blue

In BIO 139 lab this week we are studying the morphology (form, structure) of human blood cells.  We are learning to identify cells based on shape, size, color, nucleus, granules, etc.

There are two main types of cells that we are identifying on the human blood smear slide, Red Blood Cells and White Blood Cells (hence the title of this post!)

A helpful website explaining how to identify some of these cells can be found at a website maintained by the University of Nebraska Omaha.  This Blood Cells website shows photomicrographs of all of the red and while blood cells while pointing out some of the features used to identify each cell type.

Keep in mind that while identifying blood cells, where you look on the slide is very important.  This photo from the Blue Histology website shows that the area of the slide differs because of the way the blood smear is made.  A blood smear is made by placing a drop of blood at one end of the slide, then applying even pressure to spread the blood cells out across the slide.  Ideally you will have an area where the cells are spread out flat enough to see the shape and attributes of the cytoplasm and nucleus.

So, what about the "Blue" in the post title?  That refers to Basophils, which often stain with blue-colored granules.  Basophils often give students fits because they are the most rare cell type on blood smears, and are often hard to find during lab.  Blue Histology has a page with some blood cell information on it that contains several photomicrographs of basophils.  Also, here are a few other photos of basophils.

It is the presence of blue/purple granules in the cytoplasm of the basophil that is characteristic.  One way to tell a basophil from a lymphocyte is to try to view an area of just cytoplasm.  The lymphocyte will have light blue or lavender colored cytoplasm without any granules.  The basophil's cytoplasm will contain granules.

What about functions?  Helium.com gives some general functions for each of the types of white blood cells.  Of course, your lab sheet points out the table in your book that can give you similar information.

Tissues

Toward the beginning of the semester, in both BIO 135 and BIO 137, we studied types of tissues.  At the time, we studied mostly Epithelial and Connective tissue types.  Later in the semester, we then looked at Muscle and Nerve tissues.  So for the final lab practical, all tissue types can be covered on the test.

Here are some examples of photomicrographs of each of the tissue types.  The link will go to the page, you may have to scroll to find the picture of the tissue.

Simple squamous epithelium
Stratified squamous epithelium
Simple cuboidal epithelium
Stratified cuboidal epithelium
Simple columnar epithelium

Pseudostratified epithelium
Transitional epithelium
Yes, it's the same link.  The top photo of the quiz is pseudostratified, the final figure on the quiz is transitional.

Adipose tissue
Dense regular connective tissue
Dense irregular connective tissue
Both are found here.  The top figure is dense irregular and the bottom figure is dense regular.

Hyaline cartilage
Elastic cartilage
Fibrocartilage
Ground bone

Smooth muscle tissue
Skeletal muscle tissue
Cardiac muscle tissue

Nervous tissue (multipolar neuron)