Talk:Lecture - Integumentary Development

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dermal papilla - the extensions of the dermis into the epidermis.

dermatoglyphic patterns - (Greek, derma = "skin", glyph = "carving") fingers, palms, toes, and soles skin patterns.

epidermal growth factor receptor - expressed on cells in the epidermis basal layer, signaling stimulates both epidermal growth and wound healing and also mediates an inhibition of differentiation.

rete ridge - the extensions of the epidermis into the dermis. These epidermal surface thickenings extend downward between underlying connective tissue dermal papillae. This is also the site of initial eccrine gland differentiation.

Lecture History


  • Keratins are the major structural proteins of the vertebrate epidermis and its appendages, constituting up to 85% of a fully differentiated keratinocyte.
  • Together with actin microfilaments and microtubules, keratin filaments make up the cytoskeletons of vertebrate epithelial cells.
  • Traced as far back in the evolutionary kingdom as mollusks, keratins belong to the superfamily of intermediate filament (IF) proteins that form alpha-helical coiled-coil dimers which associate laterally and end-to-end to form 10-nm diameter filaments.
  • The evolutionary transition between organisms bearing an exoskeleton and those with an endoskeleton seemed to cause considerable change in keratin.
  • Keratins expanded from a single gene to a multigene family. Of the approximately 60 IF genes in the human genome, half encode keratins, and at least 18 of these are expressed in skin.
  • Vertebrate keratins are subdivided into two sequence types (I and II) that are typically coexpressed as specific pairs with complex expression patterns.
  • The filament-forming capacity of a pair is dependent upon its intrinsic ability to self-assemble into coiled-coil heterodimers, a feature not required of the invertebrate keratins (Weber et al 1988).
  • Approximately 20,000 heterodimers of type I and type II keratins assemble into an IF. Mutations that perturb keratin filament assembly in vitro can cause blistering human skin disorders in vivo.

(text from Review Article)