Zoo 113 1st Lab Exam

The upper epidermis and the lower dermis.

Two basic layers of the vertebrate skin

Ectoderm

Where the epidermis is derived from

Mesoderm

Where the dermis is derived from

Exo-skeletal derivatives

formed by the hardening of these tissues and may take various forms in different vertebrate groups.

Stratum corneum

the outer keratinized or cornified layer of the frog epidermis.

Stratum germinativum or stratum basale

The actively dividing layer of the frog epidermis.

Stratum corneum

Epidermal layer: Cells here are thin and flat and are continually being pushed outwards by the layer beneath it.

Stratum germinativum or stratum basale

Epidermal layer: Cells in this layer may be cuboidal to columnar.

Stratum corneum and Stratum germinativum/basale

the two layers of the frog epidermis consisting of epithelial tissue.

Stratum laxum and stratum compactum

Two layers of the dermis made up of connective tissue

Stratum laxum

the upper layer of the frog dermis that consists of loose connective tissue.

Stratum compactum

the lower layer of the frog dermis consisting of dense, parallel, wavy fibers

Cutaneous glands, blood vessels, and chromatophores (pigment cells)

may be observed within the dermis. The most conspicuous of these are the cutaneous glands. These glands are part of the stratum germinativum but are invaginated into the loose portion of the dermis.

Hypodermis

a layer of loose connective and adipose tissues located below the dermis connecting the skin to the muscles.

Stratum corneum, lucidum, granulosum, spinosum, basale/germinativum

Five layers of the human epidermis

Stratum corneum

Human epidermis: The outer keratinized layer containing dead skin cells. It is translucent and barely visible under a compound microscope. In the human palm skin cross-section, it is the top-most, thickest layer.

Stratum lucidum

Human epidermis: A thin layer of pale dead skin cells that is only present in thick skin

Stratum granulosum

Thin band of granulated cells containing living keratinocytes.

Stratum spinosum

Human epidermis: Contains spiny filaments that provide skin with strength and flexibility.

Stratum basale or stratum germinativum:

Human epidermis: The most basal layer of the epidermis that contains actively dividing keratinocytes and melanocytes.

Papillary and Reticular layer

Two layers of the human dermis consisting made up of connective tissue:

Papillary layer

Human dermis: The upper layer that consists of loose connective tissue that, in thick skin, can form friction ridges that give rise to fingerprints.

Reticular layer

Human dermis: The lower layer that consists of dense connective tissue. This layer contains capillaries, nerves, hair follicles, oil glands and sweat glands.

Dermal bone

Where the overlapping scales in fishes arise from

Lamellar bone

The part of the scale typically retained in teleost or bony fishes

Placoid scales

Type of scale found in cartilaginous fishes. Also called denticles.

Placoid scales

Gives the rough texture in cartilaginous fishes

Basal plate

The base of the placoid scale from which the spine arises

Spine

The sharp distal projection in placoid scales that is directed backwards

Pulp cavity

The space in the middle of the placoid scale surrounded by dentin and enamel

Ganoid scales

Scales present in bichirs, bowfins, paddlefishes, gars, and sturgeons. These scales have no underlying dental layer and is composed of only a thick layer of enamel

Canal

The hollow structure along the midline of a ganoid scale

Cycloid scales

Scales present in fishes with soft fin rays (Salmon and carp)

Circuli

concentric rings on a cycloid scale

Ctenoid

Scales present in fishes with spiny fin rays such as perches and gobies.

Cteni

Fringe of projections located on the posterior end of a ctenoid scale. Helps distinguish ctenoid scales from cycloid scales.

Reptilian scales

Scales derived from the thickening of the epidermis. Lacks bony components

Scute

Epidermal thickening that covers a large area

Plates

Dermal bones found under the epidermal scales. Present in some reptiles

Turtle

Animal with distinct shell covering their entire trunk region.

Carapace

Arched dorsal half of the turtle shell

Plastron

The flatter ventral half of the turtle shell

Bridges

Found on the lateral side of the turtle shell. Connects the plastron and the carapace.

Scutes

Composition of the external region of the carapace separated by grooves

Bony plates

The internal region of a turtle shell is composed of this which are separated by sutures

Neural scutes

Carapace: a median row of five large scutes.

Costal scutes

Carapace: four pairs of scutes found on each side of the neural scutes.

Marginal scutes

Carapace: 22-25 small scutes found along the entire margin of the carapace.

Nuchal scute

Carapace: a small, unpaired marginal scute on the mid-anterior region of the carapace.

Pygal scute

Carapace: found on the region of the tail. It is the most median posterior marginal scute.

Gular scutes

Plastron: the smallest and most anterior pair of scutes of the turtle plastron found on the neck region.

Humeral scutes

Plastron: a pair of scutes on the region of the turtle humerus.

Pectoral scutes

Plastron: the largest pair of scutes of the turtle plastron found on the chest region.

Abdominal scutes

Plastron: a pair of scutes on the turtle abdominal region.

Femoral scutes

Plastron: a pair of scutes on the region of the turtle femur.

Anal scutes

Plastron: the most posterior pair of scutes of the turtle plastron found on the anal region.

Feather follicle

These are epidermal invaginations from which feathers develop from

Contour feathers

Feathers that give shape to the body

Shaft

Contour feather: the long, stiff, median structure supporting the entire feather.

Calamus or quill

Contour feather: the hollow base of the shaft that is embedded into the skin.

Rachis

Contour feather: the part of the shaft that bears the vanes.

Vanes

Contour feather: series of barbs on each side of the rachis.

Barbs

Contour feather: soft filaments of the feather

Barbules

Contour feather: lateral projections that branch off from the barbs.

Hooklets

Contour feather: tiny hooked structures that interlock with the barbules.

Down feathers

Fluffy feathers without hooklets. Found underneath contour feathers.

Calamus

Down feather: short hollow base

Barbs

Down feather: crown of soft filaments

Filoplumes or hair feathers

Feathers scattered throughout the skin

Shaft

Filoplume: threadlike filament which may have a small number of barbs.

Hair

The presence of this feature distinguishes mammals from other vertebrates

Hair

Keratinized filaments which originate from the hair follicle embedded in the dermis

Root

Hair: the base of the hair.

Shaft

Hair: the remaining length of the hair.

Medulla

Hair: the dark, innermost layer of the hair.

Cortex

Hair: the intermediate layer of the hair surrounding the medulla.

Cuticle

Hair: the outer layer of the hair composed of overlapping scale-like cells

Claws

curved, laterally compressed keratinized projections from the tips of the digits.

Claws

May be found in some amphibians, but more commonly in mammals, reptiles, and birds where they may also be called talons.

Nails

Relatively flat, tightly compacted, cornified epithelial cells produced through keratinization on the surface of the fingers and toes.

Hooves

Enlarged keratinized plates on the tips of the digits of ungulates.

Cloven hooves

Split hooves

Unguis

Claws, nails, and hooves: The harder, dorsal or outer plate.

Subunguis

Claws, nails, and hooves: The softer, ventral or inner plate.

Dermal bone

Horn: forms the core of the horn

Keratinized sheath

Horn: Covers the dermal bone

Antlers

Most distinct feature of deer (Family Cervidae). Made of branched dermal bone attached to the frontal bone of the skull. Usually present only in males except for reindeer.

Burr

Antler: the elevated, bony rim on the base of the antler.

Beam

Antler: the central stem of the antler.

Tines

Antler: the branches of the antler arising from the beam.

Fork

Antler: the end of an antler, where the central beam divides into two tines.