Transcript placenta
What’s happening here? fission LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Chapter 46 Animal Reproduction Lectures by Erin Barley Kathleen Fitzpatrick © 2011 Pearson Education, Inc. How can each of these slugs be both male and female? Create a graphic organizer including sexual vs. asexual reproduction • Word bank: binary fission, budding, fragmentation, parthenogensis, external fertilization, internal fertilization © 2011 Pearson Education, Inc. Video: Hydra Budding © 2011 Pearson Education, Inc. Asexual reproduction Pros © 2011 Pearson Education, Inc. Cons Sexual reproduction Pros Cons Sexual con: half the number of daughters per mom Sexual reproduction Asexual reproduction Female Generation 1 Female Figure 46.3-2 Sexual reproduction Asexual reproduction Female Generation 1 Female Generation 2 Male Figure 46.3-3 Sexual reproduction Asexual reproduction Female Generation 1 Female Generation 2 Male Generation 3 Reproductive handicap of sex Sexual reproduction Asexual reproduction Female Generation 1 Female Generation 2 Male Generation 3 Generation 4 Ovulation, courtship, and reproduction are coordinated with resources, but resources can be disrupted. Ovary size (a) A. uniparens females Ovulation Hormone level Estradiol Ovulation Progesterone Time Behavior Asexual whiptail lizards are descended from a sexual species, and females still exhibit male mating behaviors Female Male- Female like (b) The sexual behavior of A. uniparens is correlated with the cycle of ovulation. Malelike parthenogenesis in aphids Gender change in fish Animal homosexuality Video: Hydra Releasing Sperm © 2011 Pearson Education, Inc. Initiated external fertilization. External fertilization Pros © 2011 Pearson Education, Inc. Cons Internal fertilization Pros Cons Parental care: Surinam toad mom mouthbrooding cichlids At what are we looking? © 2011 Pearson Education, Inc. • A cloaca of a redtailed hawk © 2011 Pearson Education, Inc. Gender-specific reproductive anatomy Accessory gland Ejaculatory duct Penis and claspers (a) Male fruit fly Ovary Testis Oviduct Spermatheca Vas deferens Seminal vesicle Accessory gland (b) Female fruit fly Uterus Vulva Animation: Female Reproductive Anatomy Right-click slide / select “Play” © 2011 Pearson Education, Inc. Figure 46.10 Oviduct Ovary Uterus (Urinary bladder) (Pubic bone) (Rectum) Cervix Vagina Urethra Body Clitoris Glans Prepuce Labia minora Labia majora Major vestibular (Bartholin’s) gland Vaginal opening Ovaries Oviduct Follicles Corpus luteum Uterus Uterine wall Endometrium Cervix Vagina Mammary Glands • The mammary glands are not part of the reproductive system but are important to mammalian reproduction – Within the glands, small sacs of epithelial tissue secrete milk – animation © 2011 Pearson Education, Inc. Male Reproductive Anatomy • The male’s external reproductive organs are the scrotum and penis • Internal organs are the gonads, which produce sperm and hormones, and accessory glands • Most mammals have a baculum (penile bone) – Raccoon’s baculum © 2011 Pearson Education, Inc. Animation: Male Reproductive Anatomy Right-click slide / select “Play” © 2011 Pearson Education, Inc. Figure 46.11 Seminal vesicle (behind bladder) (Urinary bladder) Prostate gland Bulbourethral gland Urethra Scrotum Erectile tissue of penis Vas deferens Epididymis Testis (Urinary bladder) Seminal vesicle (Urinary duct) (Rectum) Vas deferens (Pubic bone) Ejaculatory duct Prostate gland Bulbourethral gland Erectile tissue Urethra Vas deferens Epididymis Testis Scrotum Glans Prepuce Penis Accessory Glands • Semen is composed of sperm plus secretions from three sets of accessory glands • The two seminal vesicles contribute about 60% of the total volume of semen • The prostate gland secretes its products directly into the urethra through several small ducts • The bulbourethral glands secrete a clear mucus before ejaculation that neutralizes acidic urine remaining in the urethra © 2011 Pearson Education, Inc. Gametogenesis • Spermatogenesis, the development of sperm, is continuous and prolific (millions of sperm are produced per day; each sperm takes about 7 weeks to develop • Oogenesis, the development of a mature egg, is a prolonged process • Immature eggs form in the female embryo but do not complete their development until years or decades later © 2011 Pearson Education, Inc. • Spermatogenesis differs from oogenesis in three ways 1. All four products of meiosis develop into sperm while only one of the four becomes an egg 2. Spermatogenesis occurs throughout adolescence and adulthood 3. Sperm are produced continuously without the prolonged interruptions in oogenesis © 2011 Pearson Education, Inc. Figure 46.12aa Epididymis Seminiferous Sertoli cell tubule nucleus Spermatogonium Primary spermatocyte Testis Cross section of seminiferous tubule Secondary spermatocyte Spermatids (two stages) Lumen of seminiferous tubule Sperm cell Figure 46.12ab Primordial germ cell in embryo Mitotic divisions 2n Spermatogonial stem cell Mitotic divisions Spermatogonium 2n Mitotic divisions Primary spermatocyte 2n Meiosis I Secondary spermatocyte n n Meiosis II Early spermatid Sperm cell n n n n Differentiation (Sertoli cells provide nutrients) n n n n Figure 46.12ac Neck Plasma membrane Tail Midpiece Head Acrosome Nucleus Mitochondria Figure 46.12b Primary oocyte within follicle Ovary Primordial germ cell Growing follicle In embryo Mitotic divisions 2n Oogonium Mitotic divisions Primary oocyte (present at birth), arrested in prophase of meiosis I 2n First polar body Completion of meiosis I and onset of meiosis II n n Secondary oocyte, arrested at metaphase of meiosis II Ovulation, sperm entry Mature follicle Ruptured follicle Ovulated secondary oocyte Completion of meiosis II Corpus luteum Second polar n body n Fertilized egg Degenerating corpus luteum Concept 46.4: The interplay of tropic and sex hormones regulates mammalian reproduction • Human reproduction is coordinated by hormones from the hypothalamus, anterior pituitary, and gonads • Gonadotropin-releasing hormone (GnRH) is secreted by the hypothalamus and directs the release of FSH and LH from the anterior pituitary • FSH and LH regulate processes in the gonads and the production of sex hormones © 2011 Pearson Education, Inc. Hormonal Control of the Female Reproductive Cycles • In females, the secretion of hormones and the reproductive events they regulate are cyclic • Prior to ovulation, the endometrium thickens with blood vessels in preparation for embryo implantation • If an embryo does not implant in the endometrium, the endometrium is shed in a process called menstruation © 2011 Pearson Education, Inc. • Hormones closely link the two cycles of female reproduction – Changes in the uterus define the menstrual cycle (also called the uterine cycle) – Changes in the ovaries define the ovarian cycle © 2011 Pearson Education, Inc. (a) Control by hypothalamus GnRH 1 Anterior pituitary 2 (b) Inhibited by combination of estradiol and progesterone Hypothalamus FSH Stimulated by high levels of estradiol Inhibited by low levels of estradiol LH Pituitary gonadotropins in blood 6 LH FSH (c) Ovarian cycle 7 Growing follicle Maturing follicle 8 Follicular phase Corpus luteum Ovulation Ovarian hormones in blood Degenerating corpus luteum Luteal phase Estradiol secreted by growing follicle in increasing amounts 4 (d) LH surge triggers ovulation FSH and LH stimulate follicle to grow 3 Progesterone and estradiol secreted by corpus luteum Peak causes LH surge (see 6 ) 5 10 9 Estradiol Progesterone Progesterone and estradiol promote thickening of endometrium Estradiol level very low Uterine (menstrual) cycle (e) Endometrium Menstrual flow phase Proliferative phase Days Figure 46.13 0 5 10 14 15 Secretory phase 20 25 28 The Ovarian Cycle • The sequential release of GnRH then FSH and LH stimulates follicle growth • Follicle growth and an increase in the hormone estradiol characterize the follicular phase of the ovarian cycle • The follicular phase ends at ovulation, and the secondary oocyte is released © 2011 Pearson Education, Inc. Animation: Ovulation Right-click slide / select “Play” © 2011 Pearson Education, Inc. Animation: Post Ovulation Right-click slide / select “Play” © 2011 Pearson Education, Inc. The Uterine (Menstrual) Cycle • Hormones coordinate the uterine cycle with the ovarian cycle – Thickening of the endometrium during the proliferative phase coordinates with the follicular phase – Secretion of nutrients during the secretory phase coordinates with the luteal phase – Shedding of the endometrium during the menstrual flow phase coordinates with the growth of new ovarian follicles © 2011 Pearson Education, Inc. Menstrual Versus Estrous Cycles • Menstrual cycles are characteristic only of humans and some other primates – The endometrium is shed from the uterus in a bleeding called menstruation – Sexual receptivity is not limited to a time frame © 2011 Pearson Education, Inc. Hormonal Control of the Male Reproductive System • FSH promotes the activity of Sertoli cells, which nourish developing sperm • LH regulates Leydig cells, which secrete testosterone and other androgens, which in turn promote spermatogenesis © 2011 Pearson Education, Inc. Animation: Male Hormones Right-click slide / select “Play” © 2011 Pearson Education, Inc. Figure 46.14 Hypothalamus GnRH FSH LH Leydig cells Sertoli cells Inhibin Spermatogenesis Testis Testosterone Negative feedback Negative feedback Anterior pituitary • Testosterone regulates the production of GnRH, FSH, and LH through negative feedback mechanisms • Sertoli cells secrete the hormone inhibin, which reduces FSH secretion from the anterior pituitary © 2011 Pearson Education, Inc. Human Sexual Response • Two reactions predominate in both sexes – Vasocongestion, the filling of tissue with blood – Myotonia, increased muscle tension • The sexual response cycle has four phases: excitement, plateau, orgasm, and resolution • Excitement prepares the penis and vagina for coitus (sexual intercourse) © 2011 Pearson Education, Inc. Formation of the zygote and early postfertilization events. 3 Cleavage 4 Cleavage continues 5 Implantation Ovary 2 Fertilization Uterus 1 Ovulation (a) From ovulation to implantation Endometrium Endometrium Inner cell mass Cavity Blastocyst (b) Implantation of blastocyst Trophoblast • During its first 2 to 4 weeks, the embryo obtains nutrients directly from the endometrium • Meanwhile, the outer layer of the blastocyst, called the trophoblast, mingles with the endometrium and eventually forms the placenta • Blood from the embryo travels to the placenta through arteries of the umbilical cord and returns via the umbilical vein © 2011 Pearson Education, Inc. Figure 46.16 Maternal arteries Placenta Umbilical cord Maternal veins Maternal portion of placenta Chorionic villus, containing fetal capillaries Fetal portion of placenta (chorion) Maternal blood pool Uterus Fetal arteriole Fetal venule Umbilical cord Umbilical arteries Umbilical vein • The first trimester is the main period of organogenesis, development of the body organs • All the major structures are present by 8 weeks, and the embryo is called a fetus © 2011 Pearson Education, Inc. Figure 46.17a (a) 5 weeks Figure 46.17b (b) 14 weeks Figure 46.17c (c) 20 weeks Figure 46.18 from ovaries Oxytocin from fetus and mother’s posterior pituitary Activates oxytocin receptors on uterus Stimulates uterus to contract Stimulates placenta to make Prostaglandins Stimulate more contractions of uterus Positive feedback Estradiol LABOR, STAGE 1 Placenta Umbilical cord Uterus Cervix 1 Dilation of the cervix Figure 46.19b 2 Expulsion: delivery of the infant Figure 46.19c Uterus Placenta (detaching) Umbilical cord 3 Delivery of the placenta Yayyyyyyyy! Figure 46.20 Female Male Method Event Production of sperm Event Production of primary oocytes Vasectomy Oocyte Sperm transport development down male and ovulation duct system Abstinence Condom Coitus interruptus (very high failure rate) Method Combination birth control pill (or injection, patch, or vaginal ring) Abstinence Female condom Sperm deposited in vagina Capture of the oocyte by the oviduct Tubal ligation Sperm movement through female reproductive tract Transport of oocyte in oviduct Spermicides; diaphragm; progestin alone (as minipill or injection) Meeting of sperm and oocyte in oviduct Union of sperm and egg Implantation of blastocyst in endometrium Morning-after pill; intrauterine device (IUD) Treating Infertility • Modern technology can provide infertile couples with assisted reproductive technologies • In vitro fertilization (IVF) mixes eggs with sperm in culture dishes and returns the embryo to the uterus at the 8-cell stage video • Sperm are injected directly into an egg in a type of IVF called intracytoplasmic sperm injection (ICSI) © 2011 Pearson Education, Inc. Video: Ultrasound of Human Fetus 1 © 2011 Pearson Education, Inc. Video: Ultrasound of Human Fetus 2 © 2011 Pearson Education, Inc. SUMMARY FIGURE Human gametogenesis Oogenesis Spermatogenesis Primary spermatocyte 2n 2n Primary oocyte n n Secondary spermatocytes n n n n n Spermatids n n n n Sperm n n n Polar body Secondary oocyte Polar body Fertilized egg Figure 46.UN02 Reproduction Questions (answer in outline form using books, after you have watched a video or two presented by Meaghan) 1. Explain the differences between sexual and asexual reproduction. 2. Create a table of the role of the parts of the male and female reproductive anatomy 3. Explain how hormones regulate the female reproductive cycle. 4. Same thing, but for boys 5. Create a flow chart of the course of conception to birth.