Basic Histology -- Nuclei and Cytoplasm Next Home Back

You will need to identify nuclei and cytoplasm in tissue sections.

Nuclei always stain blue, with at least a rim of dark blue at their edges. We refer to this loosely as the "nuclear membrane", though of course the real nuclear membrane is only a few molecules thick and is invisible on light microscopy.

Cytoplasm is more variable in its appearance. Protein-rich cytoplasm stains dark pink. Cytoplasm that is actively synthesizing protein, by contrast, will stain rich purple. (The protein molecules stain pink; the messenger, transfer, and ribosomal RNA's stain blue.) Cytoplasm that is mostly filled with carbohydrate, lipid, or water will stain pale.

This is a pancreatic island surrounded by other pancreatic cells.

The nuclei of the island cells are quite more-or-less and rather large. The cytoplasm of the island cells is light pink. Don't expect to see cell borders.

Within the island, there are also some cells that make up the walls of the capillaries. These nuclei are dark and elongated. Don't expect to see their cytoplasm clearly.

Around the island are the glandular units that produce the pancreatic enzymes. Notice the nuclei. The cytoplasm of the cells tends to be purple near the nuclei, more pink toward the center of the unit. With your study partners, find:

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