Integument. Skin = composite organ Epidermis = superficial; epithelial tissue; ECTODERMAL Dermis = deep; connective tissue; mostly MESODERMAL Neural Crest Cells = migrate into both epidermis and dermis; ECTODERMAL. Vertebrate Integument Devel.
Stratum basale (Basal Layer) = deep layer, contacts the basal lamina, mitotically active
Keratin = proteins in superficial epidermis (keratinocytes); “harden” = cornified
Stratum corneum = heavily keratinized surface layer of epidermis (only in tetrapods)
Stratum laxum = more superficial & irregular (only in gnathostomes)
Stratum compactum = deep & more ordered
Periderm – superficial
Basal layer (stratum basale) – deep; contacts basement memb.; forms adult epidermis.
Stratified keratinous epidermis, strata laxum and compactum in dermis
Hair = keratinous epidermal outgrowth (with dermal pulp cavity)
Sweat glands = coiled, produce watery sweat for cooling or traction.
Sebaceous glands = associated with hair follicles, produce sebum.
Mammary glands = produce milk (similar to sweat & sebaceous glands)
Mammary glands form regionally along mammary ridge in all therian mammals (location and number vary).
Mammary Glands, single pair with nipples, fat and glandular tissue.
Supernumary (ectopic) nipples form along developmental “milk” line.
Hair on all surfaces EXCEPT:
palms of hands, soles of feet, lips, nipples, penis, and clitoris
Sebaceous glands on all surfaces EXCEPT:
palms of hands and soles of feet
Sebaceous glands associated with hair follicle (except on lips, nipples, penis, and clitoris).
Pimples form when a hair follicle is blocked and sebum builds up.
most common – basal cell carcinoma
most dangerous - melanoma
Enamel = acellular CaPO4, hardest vertebrate produced substance.
Epidermal; secrete to skin surface
(Exception: Multicellular slime glands in hagfishes)
Enamel (superficially), Lamellar bone (deep), lack a pulp cavity
dermal bone; dermal stratum laxum
Amia (the bowfin)
prevents water loss; protects
- thin, underlies mucous layer in lissamphibians.
- thick, “replaces” mucous layer in amniotes.
* epidermal scales of beta keratin
- primarily of neural crest cells.
Anterior to Posterior
upper first, lower jaw second.
Human = 2-1-2-3 / 2-1-2-3
Dog = 3-1-4-2 / 3-1-4-3
Mule deer = 0-0-3-3 / 3-1-3-3
2 - 1 - 2 - 3