The Epidermis Epidermis of aquatic organisms: Cornified structures include: -“______” of lamprey and hagfish -____________________of land- going amphibians -“_________” of tadpoles -Distal …

The Epidermis Epidermis of terrestrial organisms: Stratified layers gave rise to 2 categories of unique features… 1) Glands 2) Stratum corneum

The Epidermis Epidermis of terrestrial organisms: Glands fall in 2 main categories based on shape… 1) 2)

The Epidermis Epidermis of terrestrial organisms: Glands produce their secretions via 3 main modes… 1) Cell membrane (_____________) 2) Whole cells and their contents (_____________) 3) Cell fragments (_____________)

The Epidermis Epidermis of terrestrial organisms: Mucous glands not abundant… occur in areas with need for lubrication Why not abundant on terrestrial animals? What other skin structures would interfere? What areas need lubrication?

The Epidermis Epidermis of terrestrial organisms: Granular glands found mainly in terrestrial amphibians and reptiles Can produce ____________ and some ____________________ Concentrations of “noxious” granular glands found on “warts” and ___________________of toads Lizards have ___________________ Musk or ________________ in turtles and snakes

The Epidermis Epidermis of terrestrial organisms (birds): Few integumentary glands in birds… however, avian oil glands _______________ gland at rump, large in aquatic birds and some domestic birds Oil glands also line … Sometimes found around the …

The Epidermis Epidermis of terrestrial organisms (mammals): 2 major types of glands in mammals… 1) (oil glands) 2) (sweat glands)

The Epidermis Epidermis of terrestrial organisms (mammals): _________________(saccular) usually associated with hair. Exceptions... Sebum secreted into hair follicle Modified (_______________) in ear canal to secrete _______ ___________________ keep conjuctiva moist (plugged = ________________)

The Epidermis Epidermis of terrestrial organisms (mammals): _________________________ (coiled tubular glands) Evaporative cooling primary function of _________ sweat glands Found in least hairy regions Some mammals lack sweat glands Humans have greatest # per cm 2 ___________ sweat glands involved with secondary sex characteristics

The Epidermis Epidermis of terrestrial organisms (mammals): Scent glands can be sebaceous or sudoriferous Found in varying locations… - - -

The Epidermis Epidermis of terrestrial organisms (mammals): ___________________ present in both sexes and derived from a line of ectoderm called the _____________________ This tissue invades the dermis and spreads Distinct tissue above these glands develops (____________)

The Epidermis Epidermis of terrestrial organisms (mammals): Nipples can be multiple… - Different species… different placement

The Epidermis Epidermis of terrestrial organisms (mammals): During lactation, products accumulate in _____________ (usually) Suckling releases _____ and _____________ facilitates by causing smooth muscle contractions “_____________” reflex

The Epidermis Stratum corneum: Epidermal scales found only in _____________. Squamates (snakes & lizards) thickened corneum except at … Varying forms… _________, ____, __________, _________ Birds have epidermal scales on areas lacking feathers What about mammals?

Thick skin Stratum corneum: The Epidermis

Claws, hoofs and nails: Claws appeared in basal amniotes Tigers have claws… are they homologous to those of Idaho Giant Salamanders?

The Epidermis Claws, hoofs and nails: Claws, nails and hooves homologous Similar structure… * Birds can have claws on wings too Are claws shed or worn down?

The Epidermis Feathers: 3 basic types… * Feathers comprised of a quill (_________), _____ and ________. Parallel extensions from the shaft barbs are crosslinked with ________ (hooklets and flanges)

The Epidermis Feather development: _____________induces overlying ____________ to divide mitotically… resulting bump is called _____________________ Why is presence of papillary vasculature important? Tall columns form a _______________and push toward tip, becoming barbs

The Epidermis Feather development: When the barbs are still in protective feather sheath it is called a ________________ At feather maturity… bulk of papilla dies back Basale tissue retracts and then starts over again Developing feathers push old feathers out _____________________

The Epidermis Feather origins: One hypothesis is that they are derived from reptile scales… Sinosauropteryx Early development of dermal papilla is similar but remaining scenario is not Some propose they are novel structures

The Epidermis Hair: Functions of hair… _________________ (underfur and guard hairs) __________(vibrissae) __________ (spines and quills)

The Epidermis Hair morphology: Similar to feathers in that there is a ___________ __________has ________ __________ with much mitosis __________is portion under the dermis where cells are dying __________is portion of hair that is separate from follicle wall

The Epidermis Hair morphology: Thin outer covering is the ___________ Underlying zone called ___________ Inner pith is the ________ Smooth muscle associated with the follicle and originating in the dermis is the ______________

The Epidermis Horns: *

The Epidermis Baleen and miscellaneous: *Toothless whales (mysteceti) rely on __________ to filter fish and/or crustaceans (krill) * oon_showing_ischial_callosities.jpg photos/diapsids/rattlesnake_rattle.jpg

Integuments by Taxa Agnathans: Epidermis… stratified, unicellular glands, mitotically active throughout Dermis… thinner than epidermis but dense/tough

Integuments by Taxa Cartilaginous fishes: Epidermis… stratified, multicellular glands show up Dermis… ______________ and melanophores

Integuments by Taxa Bony fishes: Epidermis… many mucous glands Dermis… dermal bone/scales

Integuments by Taxa Amphibians: Epidermis… stratified, multicellular glands (mucous and granular) Dermis… attached to musculature in some, loose in others, presence of chromatophores

Integuments by Taxa Non-avian reptiles: Epidermis… stratified, thick stratum corneum (scales) Dermis… tough, some with dermal bone

Integuments by Taxa Birds: Epidermis… thin, lacks glands (except uropygial), modified epidermal layers to form feathers (scales) Dermis… thin, arrector pili muscles

Integuments by Taxa Mammals: Epidermis… Distinct strata, variety of glands, hair Dermis… exceptionally thick and tough