Chapter 41 BIOL 1000 Dr. Mohamad H. Termos Reproductive Systems Chapter 41 BIOL 1000 Dr. Mohamad H. Termos

Asexual vs. Sexual Reproduction Biology, 9th ed, Sylvia Mader Chapter 43 Asexual vs. Sexual Reproduction Asexual reproduction- parent gives rise to identical offspring; no fusion of gametes Sexual reproduction- haploid gametes fuse together resulting in genetic variation. Reproductive Systems

Biology, 9th ed, Sylvia Mader Chapter 43 Asexual Reproduction Fission: Parent splits into two parts Budding: Offspring develop as small growths on parent (hydra) Fragmentation: Part of parent is broken off and develops into a new individual (sponges, starfish) In sexual reproduction organisms may undergo parthenogenesis, or modification of sexual reproduction. Unfertilized egg can develop into an individual. Example: honey bees (males = haploid, females = diploid Reproductive Systems

Biology, 9th ed, Sylvia Mader Chapter 43 Sexual Reproduction Most animals are dioecious or separate sexes where egg of one parent is fertilized by sperm of another Some animals are monoecious (hermaphroditic); which means they contain both male and female sex organs in a single body. However, the majority practice cross-fertilization with other individuals. Animals usually produce gametes in specialized organs called gonads (Testes produce sperm, Ovaries produce eggs). Copulation: Sexual union to facilitate the reception of sperm, resulting in internal fertilization. Many aquatic animals practice external fertilization (Gametes are released and unite outside the bodies of reproducing animals). Reproductive Systems

Biology, 9th ed, Sylvia Mader Chapter 43 How Animals Reproduce Oviparous animals deposit eggs in the external environment. Many aquatic animals have a larval stage. Utilize different food source than adults. Ovoviviparous animals retain their eggs and release young able to fend for themselves Viviparous- care for developing embryo via a placenta (mammals) Reproductive Systems

Biology, 9th ed, Sylvia Mader Chapter 43 Oviparous Reptiles and birds provide eggs with plentiful yolk Development takes place in shelled egg Yolk provides nutrients Parents often tend eggs and young Reproductive Systems

Biology, 9th ed, Sylvia Mader Chapter 43 Viviparous Placental mammals are viviparous Do not lay eggs Placenta – allows exchange of material between mother and developing embryo Development occurs inside the female’s body Care of zygote and embryo Placental mammals eliminate need for shelled egg Reproductive Systems

Human Male Reproductive System Biology, 9th ed, Sylvia Mader Chapter 43 Human Male Reproductive System The Testes Paired gonads suspended in scrotum Sperm: Produced by testes. Mature within epididymis. Eventually enter vas deferens - Production of Sperm takes place in the seminiferous tubules (Tubes packed with cells undergoing spermatogenesis) Reproductive Systems

Biology, 9th ed, Sylvia Mader Chapter 43 Testis and Sperm Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. MITOSIS MEIOSISI MEIOSISII spermatogonium (diploid) primary spermatocyte (diploid) secondary spermatocyte (haploid) early spermatid (haploid) late spermatid (haploid) immature sperm (haploid) acrosome head middle piece tail nucleus of Sertoli cell end piece c. Spermatogenesis d. Sperm 9 Reproductive Systems

Human Male Reproductive System Biology, 9th ed, Sylvia Mader Chapter 43 Penis is organ used for copulation Semen (seminal fluid) contains: Sperm Secretions from: Seminal vesicles Prostate gland Bulbourethral glands Reproductive Systems

Male Reproductive System Biology, 9th ed, Sylvia Mader Chapter 43 Male Reproductive System Reproductive Systems

Human Male Reproductive System Biology, 9th ed, Sylvia Mader Chapter 43 Hypothalamus has ultimate control of hormones Gonadotropic-releasing hormone (GnRH) stimulates production of hormones by the anterior pituitary Follicle Stimulating Hormone (FSH): Promotes spermatogenesis in the seminiferous tubules Luteinizing Hormone (LH): Controls production of testosterone by the interstitial cells of testes Hormonal Regulation in Males Testosterone Major sex hormone in males Establishes and maintains secondary sex characteristics Reproductive Systems

Female Reproductive System Biology, 9th ed, Sylvia Mader Female Reproductive System Chapter 43 The Ovaries, Uterus, and Vagina An oocyte (egg) bursts from an ovary into oviduct through the fimbriae of the oviducts. Fertilization normally occurs in the oviduct Ciliary action moves the developing embryo to the uterus Embryo embeds in the uterine lining (endometrium) Cervix: Narrow end of the uterus. Opening in the cervix leads to the vaginal canal Vagina: Contains mucosal lining. Bacteria create an acidic environment. Protects against the growth of pathogenic bacteria Reproductive Systems

Female Reproductive Organs Biology, 9th ed, Sylvia Mader Chapter 43 Female Reproductive Organs Reproductive Systems

Biology, 9th ed, Sylvia Mader The Ovarian Cycle Chapter 43 Follicle: primary  secondary  vesicular (Graafian) follicle under the influence of FSH and LH Ovulation: Release of secondary oocyte from a vesicular follicle. Secondary oocyte enters an oviduct. Follicle develops in corpus luteum (Degenerates if pregnancy does not occur) Reproductive Systems

Biology, 9th ed, Sylvia Mader Chapter 43 The Ovarian Cycle Follicular Phase: FSH promotes the development of a follicle. Follicle then secretes estrogens Luteal Phase: LH promotes development of the corpus luteum. Corpus luteum then secretes progesterone Reproductive Systems

Biology, 9th ed, Sylvia Mader The Uterine Cycle Chapter 43 Sex hormones affect the endometrium A twenty-eight-day uterine cycle Days 1-5: Arteries that supply the lining of the uterus constrict and capillaries weaken Endometrium disintegrates Menses pass out of the vagina during menstruation Days 6-13: Endometrium thickens Ovulation usually occurs on 14th day Days 15-28: Endometrium doubles in thickness Uterine glands mature and produce a thick secretion Reproductive Systems

Female Hormone Levels During the Ovarian and Uterine Cycles Biology, 9th ed, Sylvia Mader Chapter 43 Female Hormone Levels During the Ovarian and Uterine Cycles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Anterior pituitary Hormone Levels FSH LH Ovarian cycle Ovarian Events developing follicles mature follicle Ovulation corpus luteum Follicular Phase Luteal Phase estrogen Hormone Levels progesterone Uterine cycle Endometrium Menstruation Proliferative Phase Secretory Phase Days 1 3 5 7 9 11 13 15 17 19 21 23 25 27 30 Reproductive Systems

Ovarian and Uterine Cycles Biology, 9th ed, Sylvia Mader Chapter 43 Ovarian and Uterine Cycles Reproductive Systems

Fertilization and Pregnancy Biology, 9th ed, Sylvia Mader Fertilization and Pregnancy Chapter 43 Embryo begins developing as it travels down the oviduct to the uterus (if fertilized) Embedded in the uterine lining several days after fertilization Placenta produces human chorionic gonadotropin (HCG) Maintains the corpus luteum until placenta begins production of progesterone and estrogen Detected in pregnancy tests 20 Reproductive Systems

Human Female Reproductive System Biology, 9th ed, Sylvia Mader Chapter 43 Human Female Reproductive System Lactation is caused by prolactin Colostrum is produced until milk production begins Reproductive Systems

Control of Human Reproduction Biology, 9th ed, Sylvia Mader Chapter 43 Control of Human Reproduction Most reliable method is abstinence Traditional birth control regimens either prevent fertilization or stop a fertilized egg from implanting Male and female condoms Contraceptive vaccines Morning‑After Pills Reproductive Systems