Integumentary System Comparative Anatomy Overview

Integumentary system – comparative anatomy overview

Amphioxus Epidermis of simple columnar cells With cilia on outside as a larva, cuticle covering postlarva Unicellular glands Dermis a very thin collagen base for epidermis

Agnathans Epidermis of stratified epithelium (not necessarily stratified squamous) With many unicellular glands (cuticle or slime coating) Cornified (epidermal) teeth (ancient forms with dermal bone “armor”) Dermis a thin very tough collagen layer With melanophores

Chonrichthyes Epidermis of stratified epithelium Mostly unicellular glands, few multicellular glands Chromatophores present in both epidermis and dermis Dermis of dense fibrous connective tissues denticles (tooth scales), spines, teeth emerge to the surface Chromatophores present in both dermis and epidermis

Osteichthyes Epidermis of stratified epithelium Mostly unicellular glands, some multicllular glands Slime covering (mucous cuticle) Dermis of two layers A loose outer layer and a deeper fibrous layer Scales of various forms ganoid enamel on dentin and lamellar bone (polypterus) enamel on lamellar bone (bowfin and gar) acellular lamellar bone on fibrous collagen ( most other fish) Chromatophores Amphibia Epidermis of stratified squamous epithelium (keratinized in some) Mostly multicellular glands with ducts (underlying the surface epithelium) Scattered large secretory cells in surface epithelium Chromatophores present in both epidermis and dermis Capillaries present in deeper epidermis for cutaneous respiration Dermis either fibrous or of both an outer loose and a deeper fibrous layer Scales absent except in some caecilians (where they are called osteoderms) Chromatophores present in both dermis and epidermis

Reptilia Epidermis of keratinized stratified squamous epithelium Special keratinized structures – scales, beaks, nails, spines Few specialized multicellular glands, no unicellular skin glands Dermis of fibrous connective tissue Subsurface dermal scales (osteoderms) present in crocodilians, turtles, and some lizards. Chromophores present in dermis (not sure about epidermis)

Aves Epidermis of thin keratinized stratified squamous epithelium Special keratinized structures – feathers, scales, beaks, nails Few specialized multicellular glands ( Uropygeal gland) no unicellular skin glands Chromophores present in epidermis and dermis

Dermis (loose and dense connective tissue?) Chromophores present in dermis and epidermis Arrector pilorum muscles Highly vascular in places

Mammalia Epidermis of thick keratinized stratified squamous epithelium Special keratinized features include hair, nails, claws, horns, hooves, tori, baleen, scales Numerous multicellular glands Chromophores present Dermis a very thick layer made of loose and dense connective tissue Arrector pili muscles Dermal bone of antlers and the armor of the armadillo