Histology

• Epidermis


  Keratinized stratified squamous epithelium
• Epidermis


  • Main cell population: keratinocytes (located in all layers of the epidermis)
• Lucidum layer


  Found in thick skin sections, between the granulosum and corneum layer
• Dermis


  Connective tissue with numerous blood vessels and nerve fibers
• Layers of dermis


  • Papillary dermis (superficial, loose connective tissue, forms dermal papillae)
  • Reticular dermis (profound, irregular dense connective tissue)
• Skin appendages


  • Hair follicles
  • Nails
  • Sweat glands
  • Sebaceous glands
• Hair strand formation


  1. Bulb cells (central->medullary, lateral->cortical, profound->cuticle)

  2. Peripheral epithelial cells form root sheaths (internal and external)

  3. Hair follicle separated from dermal layer by glassy membrane
• Sweat gland


  Secretory part, duct
• Sebaceous gland


  Secretory part, duct
• Nail


  Plates of keratinized epithelial cells
• Nail components


  • Root
  • Body
  • Eponychium
  • Distal phalanx
• Ear components


  • External ear (auricle, external acoustic meatus)
  • Middle ear (tympanic membrane, auditory ossicles, muscles)
  • Internal ear (bony labyrinth, membranous labyrinth)
• Organ of Corti


  Sensory structure responsible for auditory function, located in the cochlear canal
• Organ of Corti components

  • Sensory cells (external and internal hair cells)
  • Supporting cells (pillar cells, Deiters cells, Hansen cells, Claudius cells)
• Eye


  Photosensitive organ located in the orbit of the skull
• Eye layers


  • External layer (sclera, cornea)
  • Medial layer (choroid, ciliary body, iris)
  • Internal layer (retina)
• Eye optical system


  Cornea, crystalline (lens), aqueous humor, vitreous body
• Eye chambers


  Anterior chamber, posterior chamber, vitreous chamber
• Cornea


  • Main dioptric system of the eye, located at the anterior pole (1/6th of external layer)
• Cornea layers


  • Corneal epithelium
  • Bowman's membrane
  • Stroma
  • Descemet's membrane
  • Endothelium
• Retina


  Photosensitive, continuous with the central nervous system through the optic nerve
• Retinal cell types


  • Pigment cells
  • Photoreceptive cells (rods and cones)
  • Bipolar neurons
  • Multipolar neurons (ganglion cells)
  • Horizontal cells
  • Amacrine cells
  • Müller supporting cells
• Olfactory mucosa


  Located in the superior nasal conchae, consists of pseudostratified epithelium with olfactory cells, supporting cells, and basal cells
• The nuclei of olfactory cells are situated inferiorly to the nuclei of supporting cells