Basic Histology -- Looking at Nuclei Next Home Back

You can get practice looking at nuclei by noticing how they change as the cells develop and mature.

Busy nuclei have lots of euchromatin. Inactive nuclei have mostly heterochromatin. Nuclei of cells which plan to synthesize protein will show nucleoli.

This is skin. The epidermis is the richly cellular epithelium on the surface. Beneath it is the dermis, the fibrous layer.

The epidermis renews itself by division of cells at the dermal border, and shedding of cells from the surface. This epidermis is somewhat abnormal, since its nuclei are retained in the upper layers of the epidermis.

Notice that it is easy to see the cell borders in most of the epidermis. Notice how the nuclei change from region to region. The lowest cells have nuclei of moderate size and color. In the middle of the epidermis, the cells are actively synthesizing keratin to protect the surface. So the nuclei are very large and pale and exhibit nucleoli. On the top, the nuclei are no longer active, so they are dark. They tend to flatten as do the surface cells.

In the bottom layer of the epidermis, a few of the cells have pale cytoplasm and relatively small, dark nuclei. These are the melanocytes. They do not make much protein, and rarely divide, so their nuclei are inactive.

With your study partners, find:

Hotshots: Find blood vessels in the dermis, perpendicular to the surface.



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Kansas City University of Medicine and Biosciences