5 Vertebrate/Craniate Skin Stratified epidermis (= an epithelium)Stratum basale (Basal Layer) = deep layer, contacts the basal lamina, mitotically activeKeratin = proteins in superficial epidermis (keratinocytes); “harden” = cornifiedStratum corneum = heavily keratinized surface layer of epidermis (only in tetrapods)Dermis usually more complex (= conn. tissue)Stratum laxum = more superficial & irregular (only in gnathostomes)Stratum compactum = deep & more ordered
6 Vert./Craniate Epidermis Devel. Epidermis begins as a simple epitheliumThen forms two-layers.Periderm – superficialBasal layer (stratum basale) – deep; contacts basement memb.; forms adult epidermis.
7 Dermis Devel.First dermatome cells make layered collagen and form fibroblasts under the epidermal basement membrane = stratum compactum (contiguous with the reticular lamina)The in gnathostomes, the stratum compactum separates from the reticular lamina of the basement membrane (delaminates).The stratum laxum forms between the stratum compactum & the reticular lamina of the epidermis after delamination.
8 Human IntegumentStratified keratinous epidermis, strata laxum and compactum in dermisHair = 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)
11 Human Mammary Ridge and Mammary Glands Mammary glands form regionally along mammary ridge in all therian mammals (location and number vary).
12 Human Mammary Development Mammary Glands, single pair with nipples, fat and glandular tissue.Supernumary (ectopic) nipples form along developmental “milk” line.
13 Human Integument Hair on all surfaces EXCEPT: palms of hands, soles of feet, lips, nipples, penis, and clitorisSebaceous glands on all surfaces EXCEPT:palms of hands and soles of feetSebaceous glands associated with hair follicle (except on lips, nipples, penis, and clitoris).
14 Human Skin Problems/Disease Pimples form when a hair follicle is blocked and sebum builds up.Skin Cancermost common – basal cell carcinomamost dangerous - melanoma
15 Integumentary Bones/Scales Dermal bones = bone formed in the deep dermis around collagen by osteoblasts. e.g., some skull bonesDermal scale = bone formed in more superficial dermis around collagen by osteoblasts. (may have epidermal contributions) e.g., some “fish” scalesEpidermal scale = proteinaceous, formed by dead keratinocytes in the epidermis. e.g., reptile scales
17 Dermal (Bony) Scales Epidermis can contribute enamel. Enamel = acellular CaPO4, hardest vertebrate produced substance.Dermis can contribute 3 kinds of bone.Dentin(e) = acellular, hard bone; under the epidermisDermal Vascular Bone = cellular & vascularized/“spongy”; in stratum laxumDermal Lamellar Bone = cellular or acellular, formed in flat layers; in stratum laxum or stratum compactum
18 Dermal Scales Enamel Dentine Vascular Bone Lamellar Bone Epidermal AcellularCellularAcellular or Cellular
19 Integumentary Glands Epidermal; secrete to skin surface Unicellular Glands - Common in non-tetrapod epidermis; rare in tetrapods; usually produce mucus.Multicellular Glands - Rare in non-tetrapod epidermis; common in tetrapods(Exception: Multicellular slime glands in hagfishes)Mucus “Cuticle” – Mucus layer covering some amphibians and all non-tetrapods; protects from abrasion and pathogens
20 Hagfish & Lampreys Keratinous (epidermal) “teeth” No dermal or epidermal scales.
30 Amniote IntegumentThick stratum corneum (no mucus) - Primary barrier to water loss and infection.Epidermal derivatives made of keratin: epidermal scales, hair, feathers
31 Reptile IntegumentEpidermal scales = thickened stratum corneum separated by thinner areas of stratum corneumcan be “tiled” or overlapping.
32 Avian Reptile Integument Epidermal scales on legs & feetFeathers = modified epidermal scales (with dermal pulp cavity)Few multicellular glands
33 Mammalian Integument Epidermal scales LOST Hair = keratinous epidermal outgrowth (with dermal pulp cavity)Sweat glands = coiled, produce watery sweat for cooling or traction. (Scent glands) = modified sweat glandsSebaceous glands = associated with hair follicles, produce sebum.These form by sinking of regions of epidermis into the dermis.
43 Teeth Teeth formed by the epidermis & dermis. Thought to be derivatives of “placoid” scales around mouth.Epidermis contributes enamel.Neural crest cells in dermis contribute dentin and constitutes some of the pulp cavity.
44 Tooth DevelopmentEnamel organ = epidermis that sinks into dermis, ameloblasts make enamel.Dermal papilla = dermis surrounded by enamel organ, odontoblasts make dentine.- primarily of neural crest cells.
45 Chondrichthyan TeethRevolver Dentition = teeth develop further back in the mouth and as they mature move to the crest of the bone.Eventually fall out.teeth inusedevelopingteeth
46 Tooth Terms Homodont = all teeth similar. Heterodont = teeth that differ.Polyphyodont = teeth replaced continually throughout life.Diphyodont = teeth replaced once in life (2 sets of teeth) Mammals
48 Mammalian Teeth Anterior to Posterior Incisors = flattened teeth, 1 cusp.Canines = conical teeth, 1 cusp.Premolars = multicusped teeth, present in both first and second sets of teeth.Molars = multicusped teeth, present only in second set of teeth.
49 Incisors-canines-premolars-molars Mammalian TeethDiastema = space between teeth.Dental Formula = Count of tooth types in one half of a mammal jaws.Incisors-canines-premolars-molarsupper first, lower jaw second.Human = /Dog = /Mule deer = /