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Explore the intricate process of prenatal development from fertilization to birth, encompassing embryonic and fetal stages, organ formation, and the crucial role of placenta. Witness the miraculous transformation from a single cell to a fully developed human being.
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Early Human Development. Reproductive System . week 10
Embryonic development fertilization - 8 weeks Fetal development 9 weeks - birth Prenatal Development time period from fertilization to birth = gestation Postnatal Development
Oocyte at Ovulation • Oocyte (egg) released from ovary in Metaphase II. • Occurs on Day 14 or 15 during menstrual cycle. • Spike in LH & FSH • Travels down fallopian tube. Fig 28-1
Fertilization Taking place in ?? Viability of gametes: • Oocyte 12-24 h • Sperm 12-48 h During Menstrual Cycle, Uterus wall becomes thicker. Menses won’t occur when fertilized egg, successfully, attaches to thickened uterine wall.
The first Trimesterweeks 1-12; fetus size ~ 3 in.; weight ~ 14 g Cleavage Implantation Placenta Embryogenesis Basic organ plan and tissues laid out – most susceptible to damage or disorganization at this time
Early division of zygote into multiple cells without increase in size, partitions contents Cleavage Morula solid ball of cells Zygote Blastocyst with blastocoele cavity
Day 10 Embryo completely embedded in uterus Blastula forms first. Pluripotent Stem cells present!! Placenta begins to form.
Gastrulation: 3 Germ Layers Formed day 12: Ectoderm Nervous system Skin Endoderm Digestive System Mesoderm Heart, Lungs, Muscles
Play-Doh Embryo Development Lab Mr. Gairani
Zygote • Totipotent • Gives rise to every cell type in the body • Plancenta
Morula • Cells divide my mitosis • Totipotent • Identical twins arise from this stage
Blastula • 3rd day after conception • Hollow ball of cells • Outer layer becomes the placenta • Inner cell mass are embryonic stem cells!! • Stem cell lines • Pluripotent
Gastrula • 14 days after fertilization • 3 germ layers • Endoderm • Mesoderm • Ectoderm • Multipotent