Comparative account of vertebrate integumentary derivatives
Answers
New epidermal cells are formed continuously in the lower layers of the epidermis. In terrestrial vertebrates, new epidermal cells push more superficial ones to the stratum corneum, the outer-most epithelial layer. In the process of self-destruction, these exterior epidermal cells accumulate protein products called keratin. Keratinized or cornified skin serves to prevent water escape and to protect against friction and direct mechanical stimulation (e.g. calluses in humans). The production of all of the following structures involves keratinization:
New epidermal cells are formed continuously in the lower layers of the epidermis. In terrestrial vertebrates, new epidermal cells push more superficial ones to the stratum corneum, the outer-most epithelial layer. In the process of self-destruction, these exterior epidermal cells accumulate protein products called keratin. Keratinized or cornified skin serves to prevent water escape and to protect against friction and direct mechanical stimulation (e.g. calluses in humans). The production of all of the following structures involves keratinization: Epidermal Scales: a continuous layer of repetitious thickenings of the stratum corneum; you cannot dissect an individual epidermal scale out of the skin! These scales may be shed entirely (moulting) or in small flakes. Examine preserved specimen of snake skin and dried specimens of bird legs and feet.
New epidermal cells are formed continuously in the lower layers of the epidermis. In terrestrial vertebrates, new epidermal cells push more superficial ones to the stratum corneum, the outer-most epithelial layer. In the process of self-destruction, these exterior epidermal cells accumulate protein products called keratin. Keratinized or cornified skin serves to prevent water escape and to protect against friction and direct mechanical stimulation (e.g. calluses in humans). The production of all of the following structures involves keratinization: Epidermal Scales: a continuous layer of repetitious thickenings of the stratum corneum; you cannot dissect an individual epidermal scale out of the skin! These scales may be shed entirely (moulting) or in small flakes. Examine preserved specimen of snake skin and dried specimens of bird legs and feet. Claws and Talons: curved, laterally compressed keratinized projections from the tips of digits. See dried specimen of cat claws and bird talons.
New epidermal cells are formed continuously in the lower layers of the epidermis. In terrestrial vertebrates, new epidermal cells push more superficial ones to the stratum corneum, the outer-most epithelial layer. In the process of self-destruction, these exterior epidermal cells accumulate protein products called keratin. Keratinized or cornified skin serves to prevent water escape and to protect against friction and direct mechanical stimulation (e.g. calluses in humans). The production of all of the following structures involves keratinization: Epidermal Scales: a continuous layer of repetitious thickenings of the stratum corneum; you cannot dissect an individual epidermal scale out of the skin! These scales may be shed entirely (moulting) or in small flakes. Examine preserved specimen of snake skin and dried specimens of bird legs and feet. Claws and Talons: curved, laterally compressed keratinized projections from the tips of digits. See dried specimen of cat claws and bird talons. What are the possible functions of claws and talons?