Development of the skin and its derivatives

Transcription

1 Development of the skin and its derivatives Resources: Larsen s Human Embryology The Developing Human: Clinically Oriented Embryology Dr Annemiek Beverdam School of Medical Sciences, UNSW Wallace Wurth Building Room 234 A.Beverdam@unsw.edu.au

2 Lecture overview Skin function and anatomy Skin origins Development of the overlying epidermis Development of epidermal appendages: Hair follicles Glands Nails Teeth Development of melanocytes Development of the Dermis Resources: Larsen s Human Embryology The Developing Human: Clinically Oriented Embryology Dr Annemiek Beverdam School of Medical Sciences, UNSW Wallace Wurth Building Room 234 A.Beverdam@unsw.edu.au

3 Skin Function and Anatomy Largest organ of our body Protects inner body from outside world (pathogens, water, sun) ThermoregulaMon Diverse: thick vs thin skin, scalp skin vs face skin, etc Consists of: - Overlying epidermis - Epidermal appendages: - Hair follicles, - Glands: sebaceous, sweat, apocrine, mammary - Nails - Teeth - Melanocytes - Dermis - Hypodermis

4 Skin origins Trilaminar embryo Ectoderm (Neural crest) brain, spinal cord, eyes, peripheral nervous system epidermis of skin and associated structures, melanocytes, cranial connective tissues (dermis) Mesoderm musculo-skeletal system limbs connective tissue of skin and organs urogenital system, heart, blood cells Endoderm epithelial linings of gastrointestinal and respiratory tracts

5 Ectoderm Overlying epidermis, epidermal appendages, nerve endings

6 Neural Crest Melanocytes

7 Mesoderm Dermis, Hypodermis /2'(M0#'&62,&"'#IG&332DKN#,&"'2'G2<2'&# /2'-M0#3-<&"-3#J3-<&#'&62,&"'#IJ;"J3&K#

8 Embryonic development: Page 342 S.F. Gilbert Developmental Biology 5th edimon

9 Epidermal development Surface ectoderm Skin/Interfollicular epidermis: stramfied squamous epithelium Appendages: Hair follicles Glands (sebaceous, sweat, apocrine, mammary, lacrimal, salivary) Nails Teeth

10 !&+&32J'&%<#24#/)(%W(%<&"4233(0;3-"#&J(,&"'(6#IXURK# H&"(,&"'#42"'-M2%N#A#D&&)6# H&"(,&"'# *-6&'&%<#'&'F"-%&# *-6-3#3-G&"#

11 !&+&32J'&%<#24#/)(%W(%<&"4233(0;3-"#&J(,&"'(6#IXURK# /<"-MY0-M2%# :&&)#[[N#(%<&"'&,(-<&#3-G&"# X%<&"'&,(-<&#3-G&"#

12 StraMfied skin/ife Loricrin Involucrin KeraMn 1/10 KeraMn 5/14

13 Epidermal Appendages - Hair follicles, - Glands: sebaceous, sweat, apocrine, mammary, salivary, lacrimal - Nails - Teeth Share common developmental mechanisms

14 Hair follicle development and cycling Epidermal appendage Involved in thermoregulation/sun protection Month 2-4: Onset hair follicle development Hair follicles develop first in cranial region Month 5: most hair follicles present 5,000,000 hair follicles

15 Hair follicle development Hair germ Hair peg Bulbous hair peg Invasion of dermis cells

16 Hair follicle development OG03(%=# *-F(&6#-"&#F2"%#D(<1# Y"6<#=&%&"-M2%#24# Y%&#;%PJ(='&%<&,# 1-("6N#3-%;=2# H&"'-%&%<# U2"'-M2%#24N# $""&0<2"#J(3(#';603&# S-("#4233(03&#F;3=&# T&"'(%-3#'-<"(_# X%%&"#-%,#2;<&"#"22<#61&-<16##

17 Telogen: rest Anagen: growth Catagen: regression Postnatal hair follicle cycling

18 Epidermal gland development Epidermal appendages Sebaceous glands: sebrum/vernix Sweat glands Apocrine glands ( smelly glands) Mammary glands Salivary glands Lacrimal glands

19 Epidermal gland development Epidermal appendages Sebaceous glands: develop from hair follicle (4 weeks +) Sweat glands: develop from basal layer IFE (20 weeks+) Apocrine glands: develop in association with HFs, most lost late in fetal dev.

20 4 weeks: Mammary gland development Epidermal appendage

21 Nails

22 Nail development Ectoderm Week 10: epidermal thickening, nail field Week 11: nail anlagen moves proximally, nail folds, proximal hair fold: formamon of formamve zone h`p://discovery.lifemapsc.com/library/review- of- medical- embryology/chapter- 75- development- of- the- nails

23 Nail development Ectoderm 1`JNWW,(602+&"GB3(4&'-J60B02'W3(F"-"GW"&+(&DP24P'&,(0-3P&'F"G232=GW01-J<&"PaVP,&+&32J'&%<P24P<1&P%-(36#

24 Teeth

25 Tooth development Ectoderm/cranial neural crest derived mesenchyme &%-'&3#,&%M%# :&&)#cn##,&%<-3#3-'(%-# 8P61-J&,#"(,=&6# :&&)#an# 5&6&%01G'&# 02%,&%6-M2%# L;0)&"#-%,#/1-"J&7#9-<;"&#T&%&M06#?]]A# :&&)#dn# 5&6&%01G'&# (%+-,&6#F-6&# <22<1#F;,N#!&%<-3#J-J(33-# :&&)#[AN# RJ(<1&3(-3#0&336N## $'&32F3-6<6N#&%-'&3# # 5&6&%01G'-3#0&336N## Q,2%<2F3-6<6N#,&%M%# #

26 Week 6: dental lamina forms Tooth development Week 7-8: formamon of tooth buds: Bud stage Week 8: formamon of dental papilla: Cap and Bell Stage

27 Tooth development H"('-"G#<&&<1# []#e#[]# $,;3<#<&&<1# [c#e#[c#

28 Melanocytes

29 Melanocyte development Neural crest R"%42"67#R_J#O&33#>&6#?][]#

30 Melanocyte development Neural crest $0M+&# H"23(4&"-M2%# 5(="-M2%## (%<2## &J(,&"'(6# 5(="-M2%## (%<2## S-("#H&=6# 5(33-"7#H326#*(232=G#?]]V#

31 Melanocyte development Neural crest *&42"&#6<"-MY0-M2%# Q%6&<#6<"-MY0-M2%# *;3F2;6#1-("#J&=6# $%-=&%# 5-<"(_# S-("#4233(03&#*;3=&#!f(-%Pg-2;01&7# H(='&%<#O&33#5&3-%2'-#>&6#?][?#

32 Dermis O2%%&0M+&#M66;&#D(<1N# U(F"2F3-6<6# *322,#+&66&36# 9&"+&#&%,(%=6# /&%62"G#"&0&J<2"6# 5;603&#F;%,3&6#

33 Dermis development Somitic mesoderm Somatic lateral plate mesoderm Cranial neural crest derived mesenchyme

34 Dermis I,&"'-3#J-J(33-&#-%,#&J(,&"'-3#"(,=&6K# X%%&"#,&"'(6N##"&M0;3-"#3-G&"#

35 Lecture overview Skin Skin origins Development of the overlying epidermis Development of epidermal appendages: Hair follicles Glands Mammary glands Nails Teeth Development of Melanocytes Development of the Dermis Resources: Larsen s Human Embryology The Developing Human: Clinically Oriented Embryology Dr Annemiek Beverdam School of Medical Sciences, UNSW Wallace Wurth Building Room 234 A.Beverdam@unsw.edu.au