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The Reproductive System 1. The Male Reproductive System 2. The Female Reproductive System 3. The Menstrual Cycle 4. Embryonic Development The Male Reproductive System Urinary bladder Pubic bone Vas deferens Urethra Penis Seminal Large intestine vesicle Rectum Prostate gland Bulbourethral gland Scrotum Epididymis Testis Spermatogenesis begins when males reach puberty and lasts into old age sperm are produced in the testes and mature in the epididymis four haploid sperm cells are produced from one diploid spermatogonium The Female Reproductive System Fallopian tube Fallopian tube Ovary Urinary bladder Ovary Uterus Pubic bone Urethra Cervix Vagina Rectum Vagina Oogenesis - the formation of egg cells • females are born with up to 400,000 follicles, each of which contains a primary oocyte that is "paused" in prophase I of meiosis • beginning at puberty, hormones cause one oocyte to mature approximately every 28 days • each primary oocyte can produce 1 ovum (egg cell) and 3 polar bodies • meiosis II is not completed unless the egg is penetrated by a sperm cell The Ovarian Cycle 1. follicular phase - follicle stimulating hormone (FSH) causes a follicle and its oocyte to start to mature 2. ovulation - luteinizing hormone (LH) peaks causing the follicle to break open and release its egg, causing estrogen levels to rise, reducing the amount of FSH and LH 3. luteal phase - remaining follicle forms the corpus leuteum which secretes estrogen and progesterone which stimulate the endometrium to thicken in case of pregnancy. The Menstrual Cycle 1. menstrual phase - low levels of estrogen cause the endometrium (uterine lining) to break down and menstruation occurs 2. proliferation phase - rising estrogen levels cause the endometrium to thicken ovulation 3. luteal phase - further thickening of the endometrium, preparing for implantation of egg Fertilization and Implantation sperm cell penetrates the egg, meiosis II is completed and a diploid zygote is formed by the time implantation occurs, the zygote has already divided into about 100 cells to form the blastocyst when the first body structures appear at about nine weeks, it is called an embryo The Placenta Thought Question: How can this process result in twins? Amniotic sac Placenta Umbilical cord Fetal Maternal portion of portion of placenta placenta Villus in chorion Amnion Uterus Amnion Umbilical cord Maternal artery Umbilical arteries Maternal vein Umbilical vein Fetal Development Thought Question What evidence for evolution is shown in these images? Ultrasound Thought Question How does an ultrasound work?
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