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Animal Development

Animal Development. Chapter 46 & 47. Fig. 46-6. Vocabulary. Zygote: Single diploid cell Fertilization: Sperm & egg combine Ovulation: Egg is released from the ovary Spermatogenesis: Formation of sperm Oogenesis: Formation of the egg. Anatomy. Anatomy. Oviduct. Ovary. Uterus.

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Animal Development

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  1. Animal Development Chapter 46 & 47

  2. Fig. 46-6

  3. Vocabulary • Zygote: • Single diploid cell • Fertilization: • Sperm & egg combine • Ovulation: • Egg is released from the ovary • Spermatogenesis: • Formation of sperm • Oogenesis: • Formation of the egg

  4. Anatomy

  5. Anatomy Oviduct Ovary Uterus (Urinary bladder) (Pubic bone) (Rectum) Cervix Urethra Shaft Vagina Clitoris Glans Prepuce Labia minora Labia majora Vaginal opening

  6. Fig. 46-10b Oviduct Ovaries Follicles Corpus luteum Uterine wall Uterus Endometrium Cervix Vagina

  7. Female • Ovaries (at birth) • Contain approximately 1 million follicles • Primary oocyte • Started meiosis • Stopped at prophase I (diploid)

  8. Female • FSH • Stimulates production of a follicle • One follicle goes through Meiosis I • Two daughter cells • Secondary oocyte (starts Meiosis II) • Polar body (disintegrates)

  9. Female • LH stimulates ovary • Secondary oocyte leaves ovary • Ovulation • Fertilized then completes Meiosis II • Ovum • Polar body • Travels fallopian tube • Implants in uterus (approx. 5-6 days)

  10. Fig. 46-12g In embryo Primordial germ cell Mitotic divisions 2n Oogonium Mitotic divisions Primary oocyte(present at birth), arrestedin prophase of meiosis I 2n Completion of meiosis Iand onset of meiosis II Firstpolarbody n n Secondary oocyte,arrested at metaphase of meiosis II Ovulation, sperm entry Completion of meiosis II Secondpolarbody n Fertilized egg n

  11. Ovulation

  12. Menstrual cycle • GnRH • FSH & LH released • Stimulates follicle • Estradiol released • Follicle released (ovulation) • LH increases

  13. Menstrual cycle • Corpus luteum releases progesterone & estridiol • Corpus luteum disintegrates • Lining sheds • Endometriosis: • Uterine lining in abdomen

  14. Menstrual cycle

  15. Anatomy

  16. Fig. 46-11b (Urinarybladder) (Urinaryduct) Seminal vesicle (Rectum) (Pubic bone) Vas deferens Erectiletissue Ejaculatory duct Prostate gland Urethra Penis Bulbourethral gland Glans Vas deferens EpididymisTestisScrotum Prepuce

  17. Male • Testes are in abdomen (at birth) • Descend into scrotum • Temperature of testes is cooler • Normal sperm production • Seminiferous tubules • Contain spermatogonia or germ cells

  18. Male • Germ cells (diploid) • Mitosis • One undergoes meiosis • Produce 4 haploid sperm • Produce 100 to 200 million sperm a day • Continues for life

  19. Spermatogenesis

  20. Fig. 46-12b Epididymis Seminiferous tubule Sertoli cellnucleus Spermatogonium Primary spermatocyte Testis Cross sectionof seminiferoustubule Secondary spermatocyte Spermatids(two stages) Sperm Lumen ofseminiferous tubule

  21. Fig. 46-12c Primordial germ cell in embryo Mitotic divisions Spermatogonialstem cell 2n Mitotic divisions Spermatogonium 2n Mitotic divisions Primary spermatocyte 2n Meiosis I n n Secondary spermatocyte Meiosis II Earlyspermatid n n n n Differentiation (Sertolicells provide nutrients) Sperm n n n n

  22. Gamete formation

  23. Embryonic development • Fertilization • Cleavage • Gastrulation • Neurulation • Organogenesis

  24. Fertilization • 1. Penetration • Sperm digests cells surrounding egg • Contains glycoprotein enzymes • 2. Activation • Membrane changes • Prevents other sperm penetrating

  25. Fertilization • 2. Activation • A. stimulates egg to complete division of Meiosis II • B. stimulates movement of cytoplasm to prepare for cell division of zygote • C. stimulates increase in protein synthesis

  26. Fertilization • 3. Nuclei fusion • Sperm nucleus fuses with egg • Egg is not activated • Does not form zygote

  27. Fertilization

  28. Cleavage • Rapid cell division • Blastomeres: • Smaller & smaller cells • No increase in volume of cytoplasm • Morula: • Tight mass of approximately 32 cells

  29. Fig. 47-6 (a) Fertilized egg (b) Four-cell stage (c) Early blastula (d) Later blastula

  30. Cleavage • Blastocyst (Blastula) • Hollow ball of approx. 500-2000 cells • Blastocyst cavity • Fluid filled • Different regions in blastocyst • Received differing amounts of cytoplasm • Affects further development

  31. Cleavage • Trophoblast: • Outer layer of cells • Surround blastocyst (involved in placenta) • Inner cell mass: • Layer of dividing cells • At one end of Blastocyst • Becomes developing embryo

  32. Fig. 47-8-6 0.25 mm 0.25 mm Animal pole Blastocoel Vegetalpole Zygote 2-cellstageforming 4-cellstageforming 8-cellstage Blastula(crosssection)

  33. Cleavage • Implantation: • Blastocyst attaches to endometrium • 6 days after fertilization • Human chorionic gonadotropin (HCG) • Hormone released by trophoblast • Maintains corpus luteum

  34. Fig. 47-16-2 Expandingregion oftrophoblast Maternalbloodvessel Epiblast Hypoblast Trophoblast

  35. Gastrulation • Turning inward of cells into blastocyst • Forms germ layers • Ectoderm: • Epidermis/neural tissue • Mesoderm: • Muscle/skeletal/vasculature • Endoderm: • Gut lining, respiratory tract, liver

  36. Fig. 47-14 ECTODERM MESODERM ENDODERM NotochordSkeletal systemMuscular systemMuscular layer ofstomach and intestineExcretory systemCirculatory and lymphaticsystems Reproductive system(except germ cells) Dermis of skinLining of body cavityAdrenal cortex Epidermis of skin and itsderivatives (including sweatglands, hair follicles)Epithelial lining of mouthand anusCornea and lens of eyeNervous systemSensory receptors inepidermisAdrenal medullaTooth enamelEpithelium of pineal andpituitary glands Epithelial lining ofdigestive tractEpithelial lining ofrespiratory systemLining of urethra, urinarybladder, and reproductivesystemLiverPancreasThymusThyroid and parathyroidglands

  37. Gastrulation

  38. Gastrulation • Chorion: • Surrounds embryo • Gas exchange • Amnion: • Encloses the embryo • Protective amniotic fluid • Yolk sac: • Formation of blood cells

  39. Gastrulation Amnion Chorion Ectoderm Mesoderm Endoderm Yolk sac Extraembryonicmesoderm Atlantois

  40. Neurulation • Development of dorsal nerve cord • Notochord (spinal column) • Forms from mesoderm soon after gastrulation • Neural grove (spinal cord/brain) • Crease down the axis of the embryo • Neural tube (ectoderm) • Hollow cylinder

  41. Neural cord

  42. Neurulation • Neural crest • Cells pinch off from neural tube • Migrate to parts of embryo • Peripheral nerves, teeth, skull bones

  43. Fig. 47-12b-4 Outer layerof ectoderm Neural crestcells Neural tube (b) Neural tube formation

  44. Organogenesis • Below neural tube • Somitomeres: • Small sections of mesoderm • Somites • Smaller sections of mesoderm • Develop into muscles, vertebrae, connective tissues

  45. Organogenesis • Mesoderm surrounds the endoderm • Separates into 2 layers • One lines the inner body wall • One lines the outside of the gut • Between layers becomes body cavity

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