UNSW Embryology
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Development of the Skin, Hair
and Nails- Molecular Development
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Embryology Home
Page
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Page
Links Introduction
Integumentary
System OverviewReferencesAbout
Notes
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2 | Abnormalities
| OMIM
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3 | Pig
Stage 13/14
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4 | Human
(Stage22) | Selected
Human highpower
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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. Ectoderm forms the
surface epidermis. Mesoderm forms the underlying
connective tissue of dermis. Neural crest cells
also migrate into the forming dermis. There is a
detailed developmental
overview of all these specific structures.
This section of notes still under
development.
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Integumentary System
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.
More detailed Overview?
of other Integumentary Structures
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References
- Selected Lists of References from PubMed
March 1999 search results are available for
School of Anatomy computers without internet
access. Computers with internet access can
search from either Page
2 or PubMed
Internet Access
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About Notes
- Notes from the Embryology Program compiled and
written by Dr Mark Hill.
- Note Links to OMIM Entries are copies of originals
for computers without internet access. Computers with
internet access can directly access the database.
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m.hill@unsw.edu.au
Date Last Modified: 31/3/99
This site maintained by Dr M. Hill
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