 Dear Students,  Now that you know what is embryology, I encourage you to read from the recommended textbook.  Do not complain that the lecture contains only pictures.  Listen to the lecture carefully!!!!  Make your own notes by going through the books!!!

 Understand the development of the the embryo  Formation of bilaminar germ disc  Abnormalities of implantation & trophoblasts

 Blastocyst embedded  Trophoblast differentiates  Cytotrophoblast  Syncytiotrophoblast  Inner cell mass differentiates  Hypoblast  Epiblast  Formation of Amniotic cavity  Amnioblasts

 Lacunar stage  Formation of Heuser’s membrane  Formation of exocoelomic cavity (Primitive yolk sac)

1. Hypoblast growing ventrally 2. Eroded maternal capillaries 3. Extraembryonic reticulum 4. Heuser´s membrane 5. Amniotic cavity 6. Cytotrophoblast 7. Syncytiotrophoblast 8. Lacunae, filled with blood

 Formation of  Sinusoids  Extraembryonic mesoderm  Extraembryonic coelom (Chorionic cavity)  Extraembryonic somatopleuric mesoderm  Extraembryonic splanchnopleuric mesoderm  Decidual reaction

 Bleeding at implantation site  Formation of  Primary villi  Definitive yolk sac  Exocoelomic cyst  Chorionic cavity  Chorionic plate

 hCG – Syncytiotrophoblast  Used in Pregnancy test

 LANGMAN’S MEDICAL EMBRYOLOGY – 11 th edition  CHAPTER 4 – Second week of development Pgs. 47 – 54