1. Molecular Embryology By:Dr. Khaled El MasryAssistant Lecturer of Human Anatomy & EmbryologyMansoura Faculty of Medicine, Mansoura University, Mansoura , Egypt. 2013

2. Molecular Regulation ofCardiac Development 3. BMP 2, 4 + Inhibitors of WNT genes (In Endoderm & Lateral PlateMesoderm ) Stimulate Production of Signals from Anterior Cranial EndodermExpre ss NKX 2.5Specify Cardiogenic Field in OverlyingMesoderm. Role in CardiacSeptation.Role in Conducting System Development. TBX-5 ( anotherExpressed later than NKXtranscriptional factor) 2.5 contain T- Box. Role in Cardiac Septation 4. Molecular Regulation ofSomitEDifferentiation 5. Limb & body wall Epaxial musclesActivate Myogenin & MRF-5musclesWNT proteinsMYF-5 MYOD ( from Neural Tube) Myotubes & MyofibrilsDMMidpart NT-3 (from NeuralTube) VMSHHDermisD Sclerotome PAX 1Initiate cascade of cartilage & bone forming genes Vertebral formationLBY:Interaction ( ) BMP-4 ( from lateral plate mesoderm) & WNT proteins ( fromDr. Khaled El Epidermis)WNT proteins PAX 3 Specify Dermomyotome Region of Somites Masry ( from Neural Tube) 6. Molecular Regulation ofGut Development 7. Differentiation of different regions of gut & its derivatives is dependentuponReciprocal interaction ( ) Endoderm of GUT & Surrounding SplanchnicMesoderm.SHH ( Expressed throughout gutendoderm)Induce expressionHOX genes inMesoderm Once expressed & Mesoderm specified by HOX genesMesoderm instruct Endoderm to form various regions ofMidgut & HindgutSimilar Interactions are responsible for Partitioning ofForegut. 8. Molecular Regulation ofLIVER Development 9. All Foregut Endoderm has the ability to express liver-specific genes & todifferentiate into Liver tissue ButThis expression is blocked by factors produced from surrounding tissues including: Ectoderm, non- cardiacmesoderm & Notochord. Liver Development occurs when: Cardiac MesodermFGF4Block the inhibitory signals in prospective hepatic RegionThis process is partially Cells differentiate intoregulated by HNF 3,4hepatocytes & Biliary cell(Hepatocyte Nuclear lineageTranscription Factors 3 & 4 ) 10. Molecular Regulation of Pancreas Development 11. Notochord FGF & Suppress SHH ( inActivin gut endoderm that form the will pancreas Upregulate PDX genes ( Pancreatic & DuodenalHomeobox genes) PAX 4,6 Specifyexpressionendocrine cell lineageCells expressing Cells expressing PAX 6PAX 4 & 6 only Cells Cells Cells Cells( glucagon)(Insulin)(Pancreatic(Somatostatpolypeptide) 12. Molecular Regulation ofKidney Development 13. Differentiation of the kidney involves interaction between the epithelium of Ureteric Bud & the mesenchyme of Metanephric Cap.FGF 2 BMPUreteric Bud7 Metanephric CapRE T MET GDNF ( Glial Derived Neurotrophic Factor )HGF ( Hepatocyte Growth Factor )Thus, Signaling Pathway is established between these 14. Block ApoptosisStimulate proliferation ofMetanephric Cap FGF Maintain WT 1 2 productionBMP 7Ureteric Metanephri BudGDNc CapFHGFMake the metanephric Cap competent to WT respond to induction by Ureteric Bud1Stimulate growthRegulate productionof Ureteric Budof GDNF & HGF 15. TO BE CONTINUEDISA