Toad External Anatomy and Skin Histology

Vocabulary flashcards covering the external anatomy, anatomical planes and orientations, skin histology, and sexual dimorphism of the toad.

Anura

The order to which frogs and toads belong, representing the largest and the most diverse group of living amphibians.

Stratum corneum

The outermost stratified layer of the epidermis composed of squamous epithelial tissue of flattened, dead cells that are constantly removed during shedding.

Ecdysis (molting)

The process by which a toad sheds its skin, constantly removing the thin hardened or cornified stratum corneum.

Stratum germinativum

The innermost sublayer of the epidermis consisting of living and growing cuboidal to columnar cells that continuously divide to replace the shed stratum corneum.

Chromatophores

Specialized connective tissue situated at the junction of the epidermis and dermis that contains pigments.

Melanophores

A row of black pigment-containing cells found in chromatophores that are largely responsible for the skin's color.

Stratum laxum (stratum spongiosum)

The outer sublayer of the dermis immediately below the stratum germinativum, containing loosely arranged connective tissue, blood vessels, and cutaneous glands that give it a spongy appearance.

Poison glands

Larger cutaneous glands located in the stratum laxum of the dermis that possess a thin epithelial wall.

Mucous glands

Smaller and more numerous cutaneous glands located in the stratum laxum of the dermis that have thicker walls.

Stratum compactum

The inner layer of the dermis consisting of compactly arranged layers of white fibrous connective tissue.

Bilateral symmetry

A body plan characteristic in which an organism can be differentiated into two mirrored portions, specifically right and left halves.

Frontal plane

A directional plane that divides the body into dorsal and ventral sections.

Sagittal plane (longitudinal plane)

A directional plane that divides the body into right and left sections.

Transverse plane (cross plane)

A directional plane that divides the body into anterior and posterior sections.

Axial region

The body region composed of the head and the trunk, which are broadly joined by a very short neck that restricts head movement.

External nares

A pair of openings located at the tip of the pointed snout.

Nictitating membrane

A transparent third eyelid that keeps the toad's eyes moist when underwater.

Tympanic membrane

An ovoid region of tightly drawn skin located posterolateral to the eye that covers the auditory canal (eardrum).

Paratoid gland

A large swelling and poison gland located behind the tympanic membrane on each side of the head.

Cloacal aperture

An opening located at the most posterior part of the trunk on the dorsal side.

Appendicular region

The body region made up of the anterior forelimbs and posterior hindlimbs.

Prepollux

A rudimentary thumb found on the hand (manus) of the forelimb alongside four digits.

Prehallux

A sixth rudimentary toe found on the foot (pes) of the hindlimb alongside five webbed digits.

Amplexus

The process of false copulation during which the male uses enlarged or swollen thumb pads on its inner fingers.