Integumentary System Review

The dermis comes from which embryologic germ layer?

Mesoderm

The dermis comes from which embryologic germ layer?

Ectoderm

Fish scales originate from what layer of the skin?

• Dermis

Fish bone-like composition

• scales from dermis

• don’t penetrate the epidermis

• chromatophores present in dermis: that displayed the true color

• Scales grow at age

Fish Covered by epidermis

Keratin layer

Except in what group where scales penetrate the epidermis?

Cartilaginous fish (chondrichytes)

Reptile scales originate from what layer of the skin?

Reptile scale skin keratin present

Reptile - underlying dermal bone (osteoderms)

Larger scales in reptiles called scutes

Reptile scales give rise to feathers

Why are fish so slimy?

Mucus secretion for protection and streamlining

Fish Glands and other stuff

• unicellular (many types), mucous most common

• antimicrobial protection/predator evasion

Amphibian Glands and other stuff

• cutaneous respiration (capillaries to epidermis)

• multi-cellular glands

• mucous or poison in frogs/salamanders

Reptile Glands and other stuff

• fewer skin glands, increasing keratinization

• scales are epidermal (scutes)

• ecdysis (shedding) may be complete or patchy

Reptile skin INVERTS when injured or incised

• Use everting suture pattern to close

Closure and injections between scales

• subcutaneous, intramuscular

• Suture placement

Carapace

• hard, protective upper shell found in certain animals

• defense and structural support.

• Ribs, spinal column fuse: Ribs and vertebrae fuse directly into the carapace

Plastron

• Found in turtles and tortoises, the plastron is the ventral (bottom) part of the shell, complementing the dorsal carapace.

• Made of dermal bone

• Fused to the pectoral girdle

• Sternum: Turtles lack a sternum—their plastron replaces it functionally and structurally.

• gastralia: ventral; help with respiration, support, and protection, especially in species lacking a rigid rib cage.

Connection : bridge

the bony structure that connects the carapace (top shell) to the plastron (bottom shell).

Scutes over bone

Made of keratin

Scutes don’t always correlate with bony sutures

Melanin in scutes gives pattern

Feather tracts (pterylae)

Map out growth

Apteric tracts (apteria)

Featherless areas in between

name 3 groups of pigments found in feathers

• melanins

• Carotenoids

• Porphyrines