Blood, 40X 
Blood is an unusual connective tissue because it is normally in liquid form. It consists of a fluid called plasma and cells (formed elements) that are suspended in the plasma. The slide from which this image was prepared was a blood smear--it was made by putting a drop of blood on one end of a slide, and using a second slide to spread the blood into a thin, uniform layer over the slide. Some smears are better than others, meaning that the cells are more evenly spread out. Never use the part of a blood smear slide where cells are piled up on top of each other. Look for part of the slide where the cells are in a single layer. You can do that while you are using the 4X objective lens because you can see a larger area of the slide that way.

Blood, 100X   

Using the 10X objective lens you can see individual cells and tell the difference between red and white blood cells. You can even see platelets if you know what to look for. The platelets on this image are very faint, but you can see them in the image below.

Most of the cells you see here are erythrocytes or red blood cells. They are small and don't have a nucleus. They are thin in the middle, and look like red doughnuts in this image. The leukocytes (white blood cells) are larger than red blood cells and they have nuclei that stain dark purple. Many of the white blood cells have segmented nuclei, meaning that the nucleus is pinched into two or more smaller parts that are still connected to each other (sort of like when you twist one of those long balloons to make a sculpture). Can you find the white blood cell in this image? Its nucleus has two segments.

Blood, 400X

The red blood cells in this image are stacked up on top of each other. We included it to show you what an unacceptable smear looks like! But it does have the advantage of including two kinds of white blood cell that are different from the one seen in the image above. The leukocyte on the left has many very dark granules in its cytoplasm. The granules are so dark that you can't see the nucleus. The leukocyte on the right has a two-lobed nucleus and reddish-orange granules in its cytoplasm. Consult your textbook to find out what they are.

The thrombocytes, or platelets, do how show very well in these images. You can see them if you look very carefully between the other cells. They will look like small purple dots.

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