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Chapter 27 Reproduction and Embryonic Development PowerPoint Lectures for Biology: Concepts & Connections, Sixth Edition Campbell, Reece, Taylor, Simon, and Dickey Copyright © 2009 Pearson Education, Inc. Lecture by Richard L. Myers Translated by Nabih A. Baeshen ASEXUAL AND SEXUAL REPRODUCTION Copyright © 2009 Pearson Education, Inc. 27.1 Asexual reproduction results in the generation of genetically identical offspring Asexual reproduction – One parent produces genetically identical offspring – Very rapid reproduction – Can proceed via – Budding / Asexual reproduction of an aggregating sea anemone (Anthopleura elegantissima) by fission – Fission / – Fragmentation/regeneration Copyright © 2009 Pearson Education, Inc. 27.2 Sexual reproduction results in the generation of genetically unique offspring Some animals exhibit hermaphroditism – One individual with male and female reproductive systems – Easier to find a mate for animals less mobile or solitary Hermaphroditic earthworms mating Copyright © 2009 Pearson Education, Inc. 27.2 Sexual reproduction results in the generation of genetically unique offspring Sperm may be transferred to the female by – External fertilization – Many fish and amphibian species – Eggs and sperm are discharged near each other – Internal fertilization – Some fish and amphibian species – Nearly all terrestrial animals – Sperm is deposited in or near the female reproductive tract Frogs in an embrace that triggers the release of eggs and sperm Copyright © 2009 Pearson Education, Inc. HUMAN REPRODUCTION Copyright © 2009 Pearson Education, Inc. 27.3 Reproductive anatomy of the human female Both sexes in humans have – A set of gonads where gametes are produced – Ducts for gamete transport – Structures for copulation Copyright © 2009 Pearson Education, Inc. 27.3 Reproductive anatomy of the human female Ovaries contain follicles that Nurture eggs and Produce sex hormones Oviducts convey eggs to the uterus where embryos develop The uterus opens into the vagina through the The vagina – Receives the penis during sexual intercourse – Forms the birth canal Copyright © 2009 Pearson Education, Inc. Oviduct Ovaries Follicles Corpus luteum Wall of uterus Uterus Endometrium (lining of uterus) Cervix (“neck” of uterus Vagina Front view of female reproductive anatomy (upper portion) 27.4 Reproductive anatomy of the human male Testes (singular testis) produce Sperm and Male hormones Epididymis stores sperm as they develop further Several glands contribute to semen – Seminal vesicles – Prostate – Bulbourethral Copyright © 2009 Pearson Education, Inc. Urinary Bladder Prostate gland Seminal Vesicle (behind Bladder) Bulbourethral gland Erectile tissue of penis Vas deferens Urethra Scrotum Epididymis Testis Glans of Penis Front view of male reproductive anatomy 27.4 Reproductive anatomy of the human male Sperm production – Regulated by a negative feedback system of hormones – Involves the hypothalamus, pituitary, and testes Copyright © 2009 Pearson Education, Inc. Stimuli from other areas in the brain Releasing Hormone Anterior Pituitary FSH LH Negative feedback Hypothalamus Androgen production Testis Sperm production Hormonal control of the testis 27.5 The formation of sperm and egg requires meiosis Spermatogenesis – Occurs in seminiferous tubules – Primary spermatocytes – Formed by mitosis – Divide by meiosis I to produce secondary spermatocytes – Secondary spermatocytes divide by meiosis II to produce spermatids – Round spermatids differentiate into elongate sperm – Mature sperm released into seminiferous tubule Copyright © 2009 Pearson Education, Inc. Epididymis Testis Penis Scrotum Testis Seminiferous Tubule Cross section of seminiferous tubule Diploid cell Primary spermatocyte (in prophase of Meiosis I) Secondary spermatocyte (haploid; double chromatids) Developing sperm cells (haploid; single chromatids) Sperm cells (haploid) Center of seminiferous tubule 2n Diploid cell Differentiation and onset of Meiosis I 2n Primary spermatocyte (in prophase of Meiosis I) Meiosis I completed n Secondary spermatocyte n (haploid; double chromatids) Meiosis II n n n n Developing sperm cells (haploid; single chromatids) Differentiation n n n n Sperm cells (haploid) 27.5 The formation of sperm and egg requires meiosis Oogenesis – Begins before birth: diploid cells start meiosis and stop – Each month about one primary oocyte resumes meiosis – A secondary oocyte arrested at metaphase of meiosis II is ovulated – Meiosis of the ovum is completed after fertilization Copyright © 2009 Pearson Education, Inc. 2n Diploid cell in embryo Differentiation and onset of Meiosis I Ovary 2n Completion of Meiosis I and onset of Meiosis II n Entry of sperm triggers completion of Meiosis II Primary oocyte (arrested in prophase of Meiosis I; present at birth) Corpus First n polar body luteum Secondary oocyte (arrested at metaphase of Meiosis II; released from ovary) Growing Follicle n Second polar body n Ovum (haploid) Mature follicle Sperm Ovulation Ruptured follicle Oogenesis and the development of an ovarian follicle 27.6 Hormones synchronize cyclic changes in the ovary and uterus Ovarian and menstrual cycles – Occur about every 28 days – Hypothalamus signals the anterior pituitary to secrete follicle-stimulating hormone (FSH) and leuteinizing hormone (LH), which trigger – Growth of a follicle – Ovulation Copyright © 2009 Pearson Education, Inc. 27.6 Hormones synchronize cyclic changes in the ovary and uterus After ovulation, ovarian follicle becomes corpus luteum Corpus luteum secretes estrogen and progesterone, which – Stimulate the endometrium to thicken – Prepare the uterus for implantation of the embryo – Inhibit hypothalamus, reducing FSH and LH secretion Copyright © 2009 Pearson Education, Inc. 27.6 Hormones synchronize cyclic changes in the ovary and uterus If egg is fertilized – Developing embryo releases hormones(human chorionic gonadotropin) that maintain the corpus luteum which continue to secrete progesterone and estrogen maintaining uterine lining to complete the pregnancy. – Menstruation does not occur If egg is not fertilized – Drop in LH shuts down corpus luteum and stop secreting its hormones(progesterone and estrogen ) – Menstruation is triggered – Hypothalamus and pituitary stimulate development of a new follicle Copyright © 2009 Pearson Education, Inc. PRINCIPLES OF EMBRYONIC DEVELOPMENT Copyright © 2009 Pearson Education, Inc. 27.9 Fertilization results in a zygote and triggers embryonic development Embryonic development begins with fertilization – The union of sperm and egg – To form a diploid zygote Sperm are adapted to reach and fertilize an egg Streamlined shape moves more easily through fluids Many mitochondria provide ATP for tail movements Head contains a haploid nucleus Tipped with an acrosome containing penetrating enzymes Copyright © 2009 Pearson Education, Inc. Neck Plasma membrane Head Middle piece Tail Mitochondrion (spiral shape) Nucleus Acrosome The structure of a human sperm cell 27.9 Fertilization results in a zygote and triggers embryonic development Fertilization events – Sperm squeeze past follicle cells – Acrosomal enzymes pierce egg’s coat – Sperm binds to vitelline layer – Sperm and egg plasma membranes fuse – Egg is stimulated to develop further – Egg and sperm nuclei fuse(become diploid) Copyright © 2009 Pearson Education, Inc. 1 The sperm squeezes through cells left over from the follicle 2 The sperm’s acrosomal enzymes digest the egg’s jelly coat 3 Proteins on the sperm head bind to egg receptors 4 Sperm Nucleus Plasma membrane The plasma membranes of sperm and egg fuse 5 Acrosomal enzymes The sperm nucleus enters the egg cytoplasm Acrosome Sperm head 6 A fertilization envelope forms Receptor protein molecules Plasma membrane Sperm nucleus Vitelline layer الطبقة المحيه Cytoplasm Jelly coat الغالف الهالمي Egg nucleus 7 The nuclei of sperm and egg fuse Egg cell Zygote nucleus 27.10 Cleavage produces a ball of cells from the zygote Cleavage is a rapid series of cell divisions – More cells – Embryo does not get larger – Thus new cells are smaller in size Copyright © 2009 Pearson Education, Inc. Zygote 2 cells 4 cells 8 cells Blastula (hollow ball) Cross section of blastula Many cells (solid ball) Blastocoel Cleavage in a sea urchin 27.11 Gastrulation produces a three-layered embryo Gastrulation – Cells migrate – The basic body plan of three layers is established – Ectoderm outside—becomes skin and nervous systems – Endoderm inside—becomes digestive tract – Mesoderm in middle—muscle and bone – A rudimentary digestive cavity forms Copyright © 2009 Pearson Education, Inc. Blastula (end of cleavage) Animal pole Blastocoel Vegetal pole Gastrulation (cell migration) Blastocoel shrinking Formation of a simple digestive cavity Blastopore Gastrula (end of gastrulation) Simple digestive cavity Ectoderm Mesoderm Endoderm Development of the frog gastrula You should now be able to 1. Explain how fertility drugs have affected multiple births in the United States 2. 2. Compare the types of asexual and sexual reproduction 3. Describe the structures and functions of the male and female human reproductive tracts 4. 5. 6. 7. Describe Describe Describe Describe and compare spermatogenesis and oogenesis the events of the menstrual cycle the nature of the most common STDs the most common forms of birth control 8. Relate the structure of sperm to its roles in fertilization 9. Describe the processes of cleavage and gastrulation 10. Describe the functions of the four extraembryonic membranes 11 Describe the main changes that occur during each trimester of human development 12. Describe the most common reproductive technologies Copyright © 2009 Pearson Education, Inc. Reproduction تعــريف المصطـــلح المصطلــــــــح Angiosperms كاسيات البذور Sporophyte :The Diploid Generation. النابت البوغي :الجيل ثنائي العدد الكروموزومي. Gametophyte: The Haploid Generation. النابت الجاميطي :الجيل أحادي العدد الكروموزومي. Pollen Grain: The Male Gametophyte. حبه لقاح :النابت الجاميطي المذكر. Embryo Sac: The Female Gametophyte. الكيس الجنيني :النابت الجاميطي األنثوي. Endosperm: Central Cell Within The اإلندوسبيرم :خلية واحدة مركزية داخل الكيس الجنيني Embryo Sac Has Two Nuclei. لها نواتان. Pollination :Transfer Of Pollen From Anther عملية التلقيح :نقل حبوب اللقاح من ال ُمتك إلى الميسم. To Stigma. Double Fertilization: One Sperm Fertilizes االخصاب المزدوج :تقوم إحدى الخليتين المنويتين The Egg To Produce A Zygote, The Other بتخصيب البيضة إلنتاج الالقحة ,و تقوم األخرى باالندماج Fuses With The Central Cell Nuclei To مع النواة الخلية المركزية لتنتج نسيج اإلندوسبيرم ثالثي Produce 3n Endosperm. العدد الكروموزومي ).(3n Seed Dormancy: Embryo Growth And كمون البذرة :توقف نمو و تكوين الجنين. Development Are Suspended. Two Cotyledons = Eudicot Seeds فلقتان Single Cotyledon = Monocot Seeds فلقة واحدة Reproduction المصطلــــــــح تعــريف المصطـــلح Fruit: Developed Ovary. . مبيض مكتمل النمو:الثمرة Germination اإلنبات Asexual Reproduction: One Parent . ً ينتج أحد الوالدين ذرية متماثلة وراثيا:التكاثر الالجنسي Produces Genetically Identical Offspring. Hermaphroditism: One Individual With . فرد واحد بأجهزة تكاثر ذكرية وأنثوية:الخنوثة Male And Female Reproductive Systems. External Fertilization: Eggs And Sperm Are يتم إطالق البيض والحيوانات المنوية:اإلخصاب الخارجي Discharged Near Each Other. .بالقرب من بعضها البعض Internal Fertilization: Sperm Is Deposited يتم إيداع الحيوانات المنوية في أو:اإلخصاب الداخلي In Or Near The Female Reproductive Tract. . قريبا ً من القناة التناسلية لألنثي Gonads: Where Gametes Are Produced. . حيث يتم انتاج الجاميطات:المناسل Ovaries: Contain Follicles That Nurture تحتوي على حويصالت والتي تقوم بــ تغذية:المبايض Eggs And Produce Sex Hormones. .البيض وانتاج هرمونات الجنس Testes (Singular Testis): Produce Sperm And تنتج الحيوانات المنوية:)الخصي (مفردها خصية Male Hormones. . هرمونات الذكورة Epididymis: Stores Sperm As They Develop . يتم فيه تخزين الحيوانات المنوية وإنضاجها:البربخ Further Reproduction المصطلــــــــح Spermatogenesis: Formation Of Sperms. Oogenesis: Formation Of Ovum. Menstrual Cycle Menstruation Corpus Luteum Endometrium Cleavage: Rapid Series Of Cell Divisions. Gastrulation: Cells Migrate And Basic Body Plan Of Three Layers Is Established. تعــريف المصطـــلح عملية تكوين الحيوانات المنوية عملية تكوين البيض الدورة الشهرية الحيض الجسم األصفر بطانة الرحم . هو سلسلة سريعة من االنقسامات الخلوية:التفلج هجرة الخاليا و يتم تأسيس الخطة األساسية:التبطن . للجسم ذو الثالث طبقات