Integumentary System Development

From Embryology

Introduction

The integumentary system covers the surface of the embryo (skin) and its specialized skin structures including hair, nails, sweat glands, mammary glands and teeth. As a system it has contributions from all embryonic layers.

Ectoderm forms the surface epidermis and the associated glands. Mesoderm forms the underlying connective tissue of dermis and hypodermis. Neural crest cells also migrate into the forming epidermis and the skin is also populated by specialized sensory endings.

--Mark Hill 09:25, 14 April 2010 (EST) Page Template only - content from original UNSW Embryology site currently being edited and updated.

Integumentary Links: integumentary | Lecture | hair | tooth | nail | integumentary gland | mammary gland | vernix caseosa | melanocyte | touch | Eyelid | outer ear | Histology | integumentary abnormalities | Category:Integumentary
Hair Links  
Hair Links: Overview | Lanugo | Neonatal | Vellus | Terminal | Hair Follicle | Follicle Phases | Stem Cells | Molecular | Pattern | Puberty | Histology | Hair Colour | Arrector Pili Muscle | Hair Loss | Integumentary
Touch Links  
Touch Links: Touch Receptors | Touch Pathway | Pacinian Corpuscle | Meissner's Corpuscle | Merkel Cell | Sensory Modalities | Neural Crest Development | Neural System Development | Student project | Integumentary | Sensory System
Historic Embryology - Integumentary  
1906 Papillary ridges | 1910 Manual of Human Embryology | 1914 Integumentary | 1923 Head Subcutaneous Plexus | 1921 Text-Book of Embryology | 1924 Developmental Anatomy | 1941 Skin Sensory | Historic Disclaimer
Tinycc  
http://tiny.cc/Integument_Development
System Links: Introduction | Cardiovascular | Coelomic Cavity | Endocrine | Gastrointestinal Tract | Genital | Head | Immune | Integumentary | Musculoskeletal | Neural | Neural Crest | Placenta | Renal | Respiratory | Sensory | Birth

Some Recent Findings

  • The integumentary skeleton of tetrapods: origin, evolution, and development. Vickaryous MK, Sire JY. J Anat. 2009 Apr;214(4):441-64. PMID: 19422424

Textbooks

Objectives

  • Understand the differentiation of the epidermis and dermis.
  • Understand the formation of hair and nails.
  • Understand the formation of sweat glands, mammary glands.
  • Understand the formation of teeth.

Computer Activities

Development Overview

Ectoderm and Mesoderm Origin

4 weeks

  • simple ectoderm epithelium over mesenchyme.

1-3 months

  • ectoderm- germinative (basal) cell repeated division of generates stratified epithelium.
  • mesoderm- differentiates into connective tissue and blood vessels.

4 months

  • basal cell- proliferation generates folds in basement membrane.
  • neural crest cells- (melanocytes) migrate into epithelium. These are the pigment cell of the skin.
  • embryonic connective tissue- differentiates into dermis, a loose ct layer over a dense ct layer. Beneath the dense ct layer is another loose ct layer that will form the subcutaneous layer.
  • Ectoderm contributes to nails, hair follictles and glands.
  • Nails form as thickening of ectoderm epidermis at the tips of fingers and toes. These form germinative cells of nail field.
  • Cords of these cells extend into mesoderm forming epithelial columns. These form hair follocles, sebaceous and sweat glands.

5 months

  • Hair growth initiated at base of cord, lateral outgrowths form associated sebaceous glands.
  • Other cords elongate and coil to form sweat glands.
  • Cords in mammary region branch as they elongate to form mammary glands. These glands will complete development in females at puberty. Functional maturity only occurs in late pregnancy.

Adult Epidermal Stem Cells

The following information is from a recent study on mouse skin using a single cell labelling system with longitudinal tracing and confocal imaging.


Organization of the epidermis. Hair follicles contain stem cells located in the bulge (b, green), with the potential to generate lower hair follicle (lf), sebaceous gland (sg, orange) upper follicle (uf) and interfollicular epidermis (IFE, beige). The schematic shows the organization of keratinocytes in the IFE, as proposed by the stem/TA cell hypothesis. The basal layer comprises stem cells (S, blue), transit amplifying cells (TA, dark green), and post-mitotic basal cells (red), which migrate out of the basal layer as they differentiate (arrows).

Hair follicle development.jpg

Projected Z-stack confocal images of IFE wholemounts from AhcreERT R26EYFP/wt mice viewed from the basal surface at the times shown following induction. Yellow, EYFP; blue, DAPI nuclear stain. Scale bar, 20 microns.

Reprinted by permission from Macmillan Publishers Ltd: Nature. 2007 Mar 8;446(7132):185-9, copyright (2007)

Clayton E, Doupe DP, Klein AM, Winton DJ, Simons BD, Jones PH. A single type of progenitor cell maintains normal epidermis. Nature. 2007 Mar 8;446(7132):185-9. (MRC - Phil Jones Laboratory)

"According to the current model of adult epidermal homeostasis, skin tissue is maintained by two discrete populations of progenitor cells. ...Here we show that clone-size distributions are consistent with a new model of homeostasis involving only one type of progenitor cell. These cells are found to undergo both symmetric and asymmetric division at rates that ensure epidermal homeostasis."

References


Reviews

Articles

Search PubMed

Search April 2010 "Integumentary Development" - All (86) Review (9) Free Full Text (18)

Search Pubmed: Integumentary Development | Skin Development | Hair Development | Tooth Development

Additional Images

Terms

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2024, March 28) Embryology Integumentary System Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Integumentary_System_Development

What Links Here?
© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G