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INTEGUMENT LABORATORY EXERCISES
General trends.
As you examine material from the different vertebrate groups, identify dermis, epidermis
and the basement membrane zone. Identify as many epidermal and dermal cell types as you can;
these include ordinary (unspecialized) epidermal cells (keratinocytes, in those vertebrates with a
keratinized stratum corneum), specialized secretory and non-secretory cells and pigment cells.
Compare the thickness of the epidermis and dermis in those slides where these elements are
present; also note the differences in relative thickness of each layer in the different vertebrate
groups. Compare and contrast keratinized and other hard integumental structures among the
vertebrates.
FISH
CVH 100 Lamprey skin. Represents a so-called "primitive" condition without scales. Identify
epidermal cell types: club cells (large, start out anchored to basal membrane then migrate
apically as they mature), granule cells (round to ovoid cytoplasm, red granules), mucous
cells (more numerous toward surface, have translucent mucus granules in cytoplasm),
epidermal cells (best seen between club cells in deeper part of epidermis). How thick is
the dermis relative to the epidermis? Can you find any pigment cells? Where are they
located? Can you distinguish a dermal stratum spongiosum from stratum compactum?
What is deep to the dermis?
CVH 77 Dogfish skin. Analyse this slide in the same way as for the lamprey slide. What shape
are the epidermal cells in the stratum basale? What epidermal cell types can you
identify? The contents of some cells may have been washed out by the process of aming
the slide. There are well-developed stratum spongiosum and stratum compactum layers
in the dermis. Where are the melanocytes located? Identify a placoid scale; what
components make up this type of scale? These may not have erupted through the
epidermis in your specimen. Can you tell how the scales are anchored into the skin?
Compare these scales with the demonstration of placoid scales from another shark
species.
CVH 61 Head of developing dogfish. You will find developing dermal denticles associated with
the epithelium covering either the upper or lower jaw (cartilagenous structures) or both,
on this slide. Immature placoid scales will be associated with the integument. These will
likely not have erupted through the skin. What are the columnar cells external to the
developing placoid scales?
CVH 57 Elasmobranch placoid scales. This slide is a whole-mount of elasmobranch skin,
viewed en face. Note that only the central point of the scale emerges from the skin; the
wide base of the scale remains anchored in the skin. These scales are responsible for the
rough, abrasive surface of shark skin.
