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Animal Reproduction Chapter 42-43 Sexual vs. Asexual Reproduction Asexual offspring all have same genes no variation Sexual gametes (sperm & egg) fertilization.

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Presentation on theme: "Animal Reproduction Chapter 42-43 Sexual vs. Asexual Reproduction Asexual offspring all have same genes no variation Sexual gametes (sperm & egg) fertilization."— Presentation transcript:

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2 Animal Reproduction Chapter 42-43

3 Sexual vs. Asexual Reproduction Asexual offspring all have same genes no variation Sexual gametes (sperm & egg) fertilization mixing of genes variation

4 Fertilization Joining of egg & sperm external usually aquatic animals internal usually land animals

5 Development External development in eggs fish & amphibians in water soft eggs = exchange across membrane birds & reptiles on land hard-shell amniotic eggs structures for exchange of food, O 2 & waste sharks & some snakes live births from eggs Internal placenta exchange food & waste live birth

6 Adaptive advantages? What is the adaptive value of each type of sexual reproduction number of eggs? level of parental of care habitat?

7 Reproductive Hormones Testosterone from testes functions sperm production 2° sexual characteristics Estrogen from ovaries functions egg production prepare uterus for fertilized egg 2° sexual characteristics LH & FSH testes or ovaries

8 Sex Hormone Control in Males Hypothalamus Pituitary Testes Body cells GnRH FSH & LH testosterone

9 LH FSH estrogen progesterone lining of uterus egg developmentovulation = egg release corpus luteum days Menstrual Cycle Hypothalamus Pituitary Ovaries Body cells GnRH FSH & LH estrogen

10 Feedback corpus luteum ovary Female Reproductive Cycle pregnancy maintains uterus lining yes estrogen egg matures & is released (ovulation) egg matures & is released (ovulation) builds up uterus lining FSH & LH progesterone fertilized egg (zygote) hCG corpus luteum breaks down progesterone drops menstruation corpus luteum breaks down progesterone drops menstruation corpus luteum maintains uterus lining GnRH pituitary gland hypothalamus Endocrine System Control no

11 Egg Maturation in Ovary Corpus luteum produces progesterone to maintain uterine lining

12 Fertilization

13 Joining of sperm & egg sperm head enters egg

14 Fertilization causes changes… yolk found at vegetal hemisphere embryo at animal hemisphere (pigmented) post fertilization, animal pole rotates to where sperm penetrates the eggforming the gray cresent

15 …which sets up signal cascades to help set up the body plan.

16 Cleavage Repeated mitotic divisions of zygote 1st step to becoming multicellular unequal divisions establishes body plan different cells receive different portions of egg cytoplasm & therefore different regulatory signals

17 Cleavage zygote morula blastula establishes future development blastula blastocoel blastomere blastula blastocoel blastomere

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19 Stem cells pluripotent cells in bone marrow produce all types of blood cells cells differentiate in bone marrow & lymph tissue Blood Cell Production

20 Gastrulation Establish 3 cell layers ectoderm outer layers skin, nails, teeth, nerves mesoderm blood, bone & muscle endoderm inner lining digestive system ectoderm mesoderm endoderm

21 Hox Genes found in animals to determine body plan! Chapter 19!

22 Hox Genes genes that control differentiation on anterior-posterior axis hedgehog v. sonic hedgehog

23 Hox Genes Eric Wieschaus for his discoveries concerning the genetic control of early embryonic development 1980s | 1995 Eric Wieschaus

24 Human Fetal Development 7 weeks4 weeks

25 Sex Determination XY XX Testes Y SpermZygote Ovum Sperm Ovum X X X Indifferent gonads SRY No SRY Ovaries (Follicles do not develop until third trimester) Seminiferous tubules Develop in early embryo Leydig cells

26 Human Fetal Development 10 weeks chorionic villus samplingas early as week 8

27 Human Fetal Development 12 weeks20 weeks amniocentesis: weeks 14-18

28 Human Fetal Development The fetus just spends much of the 2 nd & 3 rd trimesters just growing …and doing various flip-turns & kicks inside amniotic fluid Week 20

29 Human Fetal Development 24 weeks (6 months; 2nd trimester) fetus is covered with fine, downy hair called lanugo. Its skin is protected by a waxy material called vernix

30 Human Fetal Development 30 weeks (7.5 months)

31 Getting crowded in there!! 32 weeks (8 months) The fetus sleeps 90-95% of the day & sometimes experiences REM sleep, an indication of dreaming

32 Birth Hormone induction positive feedback

33 Intestine Placenta Umbilical cord Wall of uterus Vagina Cervix Birth (36 weeks) Bladder

34 The end of the journey! Any Questions!


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