BIOL 315 1st Edition Lecture 4 Outline of Last Lecture I. Cytoplasmic Components (continued)II. The NucleusIII. The Human Body PlanIV. Medical Imaging TechniquesOutline of Current Lecture I. Concept of differentiationII. Embryonic vs. fetal periodIII. EmbryologyCurrent LectureHuman Embryology: Prenatal Development (38 weeks)I. Concept of differentiationa. Different cell typesb. Limitation of potentialII. Embryonic vs. Fetal Perioda. Embryonic Period (8 weeks)b. Fetal Period (30 weeks)III. Embryologya. Fertilization leads to a zygoteb. Day 3: morula (12-60 cells)c. Day 4: morula uterus blastocysts (Days 4-7)d. Days 6-9 blastocyst burrows into uterus walli. Embryoblast: within blastocystii. Embryonic disc made of 2 layers1. Epiblast and hypoblastiii. Embryonic disc is located where the amniotic sac and yolk sac meetIV. Day 14- Primitive Streaka. Cells moving inwardThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.b. 2 layered becomes 3 layers (called gastrulation)i. Most of body forms in front of primitive streakii. Now primitive streak: part of butt crackiii. Epiblast cells go into primitive streak, fused into hypoblast, displace hypoblast = endodermiv. Middle layer forms: mesodermv. Epiblast becomes ectoderm vi. 3 Germ layers1. Ectoderm: epidermis of skin2. Endoderm: lining of gut (but not skin)3. Mesoderm: almost everything elsec. Ectoderm & endoderm: epithelia sheetsd. Mesoderm: mesenchyme (only present in embryo) cells not attached to each otheri. Cells wanderii. Cells are star shapede. Notochord forms @ primitive nodei. Body axis divides into right/lefV. Days 17-22a. Paraxial mesoderm near notochordae processi. Somites formb. Intermediate mesoderm- into segmentsc. Lateral plate (not segments)i. Clef grows and splits lateral plate into 21. Clef = coelomd. Splanchnic mesoderm (bottomish)e. Somatic mesoderm (upperish)f. Refer to figure 5.3 for the following:i. CNS forms from ectoderm that pushes in notochord sends signal to ectoderm telling to form spinal chord/brain1. Neural fold, neural crest, neural tube becomes CNSg. Yolk sac primitive gut tubei. Body folds in at head and tailVI. 4th week cylindera. Notochord = nucleus pulpous b. Somites- segmented piecesi. Divides into 3 groups of cells:1. Dermatome dermis of skin (dorsal)2. Sclerotome vertebrae (“hard piece”)a. Surrounds notochord3. Myotome muscle of trunk and limbsVII. Intermediate mesoderm : kidney and gonadVIII. Lateral platea. Splanchnic mesoderm: gut muscle and serous membraneb. Somatic mesoderm :i. Serous membraneii. Limb bone, dermisiii. Most of dermis in
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