Georgia O'Keeffe, Summer Days



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Box Turtle Carapaces - from turtles of diverse ages showing growth pattern, healed wound on largest shell & underlying bone in shell.

Pond Turtle Carapace & Plastron - Exterior views showing epidermally derived keratin overlaying the dermal bones of the shell.

Keratin scutes are shed periodically from a pond turtle's shell.

Pond Turtle Carapace & Plastron - Interior views showing the dermal bones comprising part of the shell.


Shed snake skin + the rattle from a rattlesnake are epidermally derived & made of keratin.

Close up of part of a boa shed skin, showing the ventral scutes & dorsal scales (insideout).

Lizard - pieces of shed skin from a varanid lizard. The granular (rounded) scaled section is from the back & the rectangular scaled section is from the belly.

Claws & toes from a large monitor lizard

Snake skin - low power microscope slide.

Snake skin - high power showing the thin epidermal scale & the thin underlying dermis. Note the chromatophores.


Alligator osteoderms that are below the epidermal scales, give their skin that bumpy surface.


Primary flight Feathers on a bird's wingare asymmetrical and the barbules have hooks (not visible) that link adjacent barbs together to form the vane of the feather. All bird feathers are epidermally derived & made of keratin.

Contour feathers from a flightless bird (Emu) lack hooks on the barbules, so the barbs remain separated on the shaft.

Sampler of some of the color variation in bird feathers.

Semi-plume Feathers are below the contour feathers on a bird & they aid in insulation.

Penguin wings are covered with numerous, but minute feathers that are used for insulation, but no longer aid in flight or swimming.

Closeup of a small semi-plume with a down feather attached.

Uropygial gland of a pigeon.

Bird skin - low power showing epidermis, feather follicles & the delicate dermis.


Bird feather follicle - high power showing the formation of feather barbs & the chromatophores.


Ungulate Horns - showing Pronghorn (forked), impala? & bighorn sheep. The horns have a bony core (on skulls). The pronghorn sheds its horn annually but the other horns continue to grow throughout the life of the animal.

Rhino Horn - These views are of portions of the lower end of the horn. The horn is made of compact keratin fibers.

Rhino Horn - full view of a very long rhino horn, one of a pair that were donated to us by Mus. of History & Industry.

Beaver Tail is covered by epidermal scales (keratin) with a few sparse hairs (not visible).

Beaver Fur - showing the guard hairs, note the circular patch where guard hairs have been cut to expose the underfur.

Beaver Fur - The guard hairs have been pulled back to expose the denser, shorter underfur.

Central section of Armadillo body showing its armor plating.

Armadillo Shell - in a small portion of the armadillo's body. Keratin scales cover its shell, but beneath the keratin there are plates of bony (osteoderms). The osteoderms show up as the lighter regions where the keratin scales were removed.

Armadillo Shell - showing some of the hairs that grow between the epidermal scales.

Porqupine Quills are made of keratin & are thus simply highly modified hairs.

Horse Hoof -is covered with keratin & is a homolog to the claws or fingernails of other amniotes.

Human Palm - this part of our skin shows "ridges" that form the whorls & patterns on hands. The stratum corneum layer of the epidermis is very thick, semi-transparent & contains a spiraled duct for an eccrine sudoriferous sweat gland. The remaining epidermis is dark red while the dermis shows lots of connective tissue stained green.

Human Skin - Eccrine Sudoriferous Gland - epidermal cells form small coiled tubular glands that produce the watery fluid we call true sweat. This fluid is released to help the body cool off & thus prevents overheating.

Human Dermal Papilla at high power shows a network of capillaries inside. These blood vessel s supply nutrients to the overlying epidermis.

Human Axillary (armpit) Skin has a few of these apocrine sudoriferous glands that have larger lumens than the eccrine sudoriferous glands. Apocrine sudoriferous glands produce a more sticky sweat that contains pheromones.

Human Skin - Eccrine Sudoriferous Gland in this case it is surrounded by adipose tissue. Note the tiny lumen (opening) in different sections of the gland.

Human Adipose Tissue

Human Scalp -numerous hair follicles are visible at low power.

Hair follicles at high power.
Sebaceous (oil) gland at high power.
Mammary Gland - Active at high power to show enlarged alveoli.
Mammary Gland - inactive at low power showing skin & lymph node near mammary tissue.

Mammary Gland - inactive at high power.

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