Development of skin

Embryology

The development of skin consists formation of:

  • Epidermis
  • Dermis
  • Subcutaneous tissue
  • Hair
  • Sweat glands
  • Sebaceous glands

(I) Epidermis:

  • Ectoderm
  • Neural crest cells – Form melanoblasts (melanin secreting cells)

(II) Dermis – paraxial mesoderm (dorsal portion) – dermatome (contributes skin, fat and connective tissue)

(III) Subcutaneous tissue – lateral plate mesoderm – somatic layer (most of the skin derived)

(IV) Hairs:

  • Solid ectodermal buds sink into underlying mesenchyme
  • Forms hair bud, which is invaginated by mesoderm
  • Forms hair papilla
  • Muscle fibers attach to hair follicles – errector pili muscles
  • Hair bulb central cells elongate and keratinize – hair shaft
  • Fetus first hair – lanugo hair
Image result for Development of hair

(V) Sweat glands:

  • Solid ectodermal buds sink into underlying mesenchyme
  • Terminal end coils and it canalizes
Image result for Development of sweat glands

(VI) Sebaceous glands:

  • Side branches of hair follicle buds
  • Central cells degenerate forming fatty secretions

Congenital anomalies:

  1. Ichthyosis – dry scaly skin
  2. Hypertrichosis – excessive hair
  3. Atrichia – congenital absence of hair
  4. Dermoid – cystic swelling along lines of fusion