fertilization

fertilization

1. fusion of membranes and pronuclei of sperm and oocyte

   • Embryology lecure 1
   • forms the zygote
     • division of blastomeres to form the 16-cell morula (mulberry)
       • compaction allows formation of tight junctions to pump fluid into the center of the morula
         • forms the blastocyst
           • inner cell mass (& amniotic cavity)
             • Embryo
             • Inner cell mass: AKA embryoblast
               • embryonic stem cells derived from inner cell mass
               • hypoblast
                 • yolk sac cavity
                   • extraembryonic mesoderm
                     • large cavities form and converge
                       • chorionic cavity
               • epiblast
                 • amnioblasts
                   • amniotic cavity
                     • surrounded by chorionic cavity
           • outer cell mass
             • trophoblast
               • fetal contribution-->placenta
               • cytotrophoblast (inner layer)
                 • extraembryonic mesoderm
                   • lines the cytotrophoblast and amnion
                   • chorionic plate
                     • connecting stalk
                       • the only place where embryonic mesoderm traverses the chorionic cavity
                       • umbilical cord
               • syncytiotrophoblast (outer layer)
                 • human chorionic gonadotropin (hCG)
                   • pregnancy tests
               • primary villi
                 • cells of cytotrophoblast proliferate and penetrate into the syncytiotrophoblast and are surrounded by synctium
             • flatten to for epithelial wall of blastocyst

2. restoration of diploid number of chromosomes

3. determination of chromosomal sex

4. initiation of cleavage