Ch. 46

1 Essential Questions:

How do achieve reproductive success?

What diverse mechanisms do animals use to reproduce?

2 Two types of reproduction: 1. Asexual­ no fusion of and are involved to make offspring sea anemones budding

3 fission ­ Separation of parent organism into two individuals of equal size budding ­ new individuals forming and then splitting off from other ones gemmules­ in , several types of cells come together in and a protective coat surrounds them fragmentation ­body breaks into pieces and creates new adults, associated with regeneration ex. sponges, cnidarians, tunicates, Linckia sea stars

4 some organisms can do either sexual or asexual depending on conditions ex. Daphnia­ can produce two depending on environment one can be fertilized, one develops by parthenogenesis ­egg can develop without being fertilized (adult would be haploid ­ no to make ) ­asexual under favorable conditions, sexual under unfavorable

­In bees, males (drones) are produced this way male are produced from fertilized egg queen sterile female worker

5 parthenogenic lizards ­no males in species, all female but can behave as males during breeding season ­eggs undergo doubling in chromosomes from meiosis without fertilization both are females, one on top is behaving as a male

every two/three weeks ­ switch roles ­related to

6 male and female behaviors are related to ovulation and levels

Ovulation ­ the release of mature eggs

7 2. ­where (ovum or ) fuse to form a (fertilized egg) sperm = motile ovum = nonmotile function ­ increase genetic variability

Utethesia ornatrix red beetles

8 Why do animals have reproductive cycles? a. conserve resources and reproduce when have lots of energy b. reproduce when conditions are favorable for offspring survival

­controlled by and environmental factors (temperature, rainfall, length of daylight, lunar cycles)

Hermaphroditism­individual with both male and female reproductive organs can fertilize themselves or a mate ex. earthworms

9 sequential hermaphroditism (sex reversal)­ individual reverses its sex during its lifetime protogynous = female first protandrous = male first

Wrasses ­ live in harems, if male dies, largest female becomes male, produces sperm instead of eggs

Oysters are protoandrous ­ females are larger and lay more eggs

10 What are the mechanisms of sexual reproduction? Fertilization ­ union of egg and sperm ­eggs and sperm come together in the external environment

­Produce huge numbers of , but small number survive ­must have moist habitats ­depends on timing

11 ­can have courtship behaviors, trigger release of eggs ex. , ­once one organism has released eggs, may trigger other organisms to also release their eggs

*need moist environment ­ why?

­pheromones­chemical signals that influence behavior of others mate attractants ­minute amount is very powerful ex. gypsy moth

12 ­ sperm deposited in female reproductive tract where fertilization occurs ­requires specific reproductive structures (copulatory organs and receptacles) ­places for storage and transport of eggs ­usually reproduce fewer offspring, have a better tendency to survive ­greater parental care ­resistant ­can retain in body for development ­pouch,

13 Parental care giant water bug protects offspring by gluing them to the back of the male he keeps them moist

14 Reproductive systems can be complex or simple parasitic flatworm

complex

simple­ polycheate worms: separate but no eggs and sperm develop from undifferentiated cells lining the coelom

15 Honeybee reproductive structures

spermatheca­ sac that can store sperm for up to a year cloaca­common opening for digestive, excretory and reproductive systems in nonmammalian

16 Human Male

17 external organs = a. scrotum ­ holds testes at lower body temp. b. penis­copulatory organ internal organs = a. testes ­ contain seminiferous tubules (sperm form here) ­Leydig cells produce testosterone and androgens b. epididymus­where sperm passes from seminiferous tubules, where sperm mature (20 days)­become motile c. vas deferens­ tube from epididymus during where sperm travel

18 d. ejaculatory duct ­ tube from vas deferens to urethra e. urethra­ tube to external body, carries both and urine (not at same time) f. glands that add substances along the way 1. seminal vesicles­provide thick, yellow, basic fluid for sperm (60% of semen volume) 2. prostate gland ­ largest semen secreting gland;thin, milky ­contains anticoagulant enzymes and citrate (sperm nutrient) ­problem in men over 40 ­ gets enlarged and cuts off flow of urine, can be cancerous ­test with digital rectal exam

19 3. bulbourethral gland­ pair of glands below prostate ­secretes clear fluid that neutralizes any acid in urethra before semen comes through ­does contain some sperm (bad for withdrawal method of birth control)

­ejaculated semen = 2­5ml of semen (1 tablespoon) 1ml =50­130 million sperm ­prostaglandins in semen thin­ mucus of and help contract uterus ­semen initially coagulates (uterine contractions help it move) and then anticoagulant breaks it apart so sperm can swim

20 penis­made of erectile tissue, fills with blood during some animals (walruses, raccoons, rodents) have a baculum­bone inside the penis

impotence­inability to maintain an erection causes: alcohol, drugs, emotional problems treatments: penile implants, Viagra(relaxes smooth muscles of blood vessels so blood can enter) glans penis ­ tip of penis prepuce­ foreskin, removed during circumcision

21 anterior view

22 Female Reproductive System

23 external organs a. clitoris­ made of erectile tissue b. ­ folds of skin surrounding clitoris and vagina labia minora­slender skin folds labia majora­thick, fatty skin folds, around labia minora internal organs­ a. ­ in abdominal cavity, attached to uterus by mesenteries ­contains follicles (egg surrounded by layers of follicle cells, protect and nourish egg) ­ born with 400,000 follicles, only a few hundred released during life ­produces estrogens­ female sex hormones

24 ovulation­process of egg being expelled from remaining follicle tissue becomes corpus luteum in ovary ­corpus luteum secretes estrogens and progesterone (maintains uterine lining during ) ­if egg not fertilized, corpus luteum disintegrates b. ­ , has fimbrae that pull egg into oviduct, where fertilization occurs c. uterus­ womb, muscular, where embryo matures endometrium ­ lining of uterus d. cervix­end of uterus that opens into the vagina e. vagina­ birth canal, thin walled tube, receives penis during intercourse f. hymen­membrane that partially covers the vagina

25 Internal organs

26 ovary follicle

27 Ovulation

28 g. mammary glands­present in males and females ­usually only function in women ­low level of estrogen in men prevent form developing

29 How are sperm and eggs made? = process of making sperm ­occurs in seminiferous tubules

30 seminiferous tubules sperm

31 sperm structure

32 ­process of making eggs (ova) FSH ­ follicle stimulating hormone­ stimulates a follicle to grow, makes primary to complete meiosis I and start meiosis II ­penetration of egg by sperm cell triggers completion of meiosis II

33 oogenesis in ovary

34 How are hormones involved? In male­ ­androgens (testosterone ­ most important) responsible for primary (development of ducts, external anatomy, sperm production) and secondary sex characteristics (deepening of voice, facial/axillary/pubic hair, thickening of muscles)

­sex drive, aggressiveness

­controlled by hypothalamus and anterior pituitary

35 Hormonal control of testes

LH­ stimulates FSH ­ acts on Leydig cells to seminiferous make tubules to androgens, increase stimulate sperm spermatogenesis production

36 In females­ two cycles in female a. ­ in humans and primates humans ­ about 28 days b. estrous cycle ­ other mammals (called heat) these mammals only copulate around time of ovulation ­both have ovulation after endometrium thickens ­if no egg fertilized ­in ­ uterine lining sheds (menstruation) ­in estrous ­ endometrium is reabsorbed by uterus

37 How does the menstrual cycle work? day 1 = first day of menstruation (menstrual flow phase) ­ usually lasts a few days ~ day 5 endometrium begins to regenerate and thicken (1­2 weeks) (proliferative phase) day 14 ­ ovulation day 14­28 ­endometrium continues to thicken, and develops glycogen producing glands (secretory phase) if no egg implants, cycle starts over

38 What about the ovarian cycle? parallels the menstrual cycle follicular stage ­ several follicles start to mature egg enlarges in follicle and coat of follicle thickens (only one continues to grow) ­ends with ovulation ­follicle and ovary wall rupture­releases secondary oocyte ­corpus luteum secretes female hormones during cycle starts again with new follicles forming

39 What roles do hormones play in these cycles? Five hormones: a. GnRH­ gonadotropin­releasing hormone ­released by hypothalamus ­regulates FSH and LH release from pituitary ­triggered by of ovarian cycle b. FSH ­ follicle stimulating hormone ­stimulates follicle growth ­secreted by anterior pituitary ­gonadotropin c. LH ­ luteinizing hormone ­after ovulation ­ stimulates transformation of follicular tissue to corpus luteum ­secreted by anterior pituitary ­gonadotropin

40 d. Estrogens ­secreted by growing follicles, and later by corpus luteum ­signal uterus to start thickening endometrium ­increasing estrogen inhibits FSH and LH production (neg. feedback) ­high level stimulates production of FSH and LH ­responsible for secondary sex characteristics (pubic/axillary hair, fat in breasts and hips, increased water retention, development, sexual behavior) e. progesterone ­secreted by ovaries, and later corpus luteum ­in positive feedback ­ increase in LH conc. caused by increasing estrogen induces final maturing of follicle ­ovulation occurs 1 day after LH surge

41 ­usually start between 46­54 ­considered menopause if have not had menstrual cycle for 1 year ­ovaries lose response to gonadotropins ­declined production of estrogen ­symptoms: "hot flashes", decrease lubrication of vagina, some may grow some facial hair ­treatment ­ estrogen replacement therapy herbal remedies

42 43 What happens in pregnancy? pregnancy = gestation human = 266 days, rodents = 21 days, elephants = 600 days Three trimesters a. first trimester zygote begins cleavage, after 3­4 days is ball of cells ­ ­ sphere of cells with flattened cavity, implants into endometrium (grows over blasotsyst) ­placenta is formed ­ for nutrients, gas exchange and disposal of metabolic wastes

44 organogenesis ­ heart (4th week), other organs develop ­is fetus at end of first trimester ­human chorionic gonadotropin secreted by embryo to maintain secretion of estrogen and progesterone, if did not take over for LH from mother could get spontaneous abortion ­detected by pregnancy tests ­progesterone helps form mucus plug over cervix ­mother's breasts enlarge

45 formation of blastocyst

46 b. second trimester ­fetus grows quickly to 30 cm. ­mother feels movement, by middle can see movement on stomach area ­placenta secretes progesterone, HCG decreases ­abdominal area grows, pregnancy obvious c. third trimester ­rapid growth to 3­3.5 kg (~ 7 pounds) ­50 cm length ­fetal activity may decrease due to lack of space ­mother's abdominal organs are compressed and moved ­estrogens very high at end of trimester, trigger oxytocin receptor formation on uterus ­oxytocin produced by fetus and mother's anterior pituitary gland stimulate uterine contractions (positive feedback)

47 Placental development

48 Human fetal Development

49 Birth (partuition) uterine contractions (labor) first stage ­ cervix thins and opens second stage ­ expulsion of baby final stage ­ delivery of placenta

50 Stages of delivery First stage

Second stage

Third stage

51 ­unique to mammals

­decreased progesterone shut off negative feedback of anterior pituitary ­ allow prolactin production (stimulates milk production after 2­3 days)

­becomes postive feedback mechanism

­colostrum is initial fluid coming out of breast before milk comes in (contains maternal antibodies that help infant until own immune system kicks in)

52 How come the baby is not rejected as foreign when it contains the father's genes?

­trophoblast­helps with implantation and becomes part of fetal placenta ­believed to prevent immune response by inhibiting mother's T­lymphocytes by making "suppressor" T­cells, so can't attack foreign tissue ­if male surface antigens are similar to mother's, no suppressor cells get made and embryo is attacked­ may be cause of miscarriages ­other hypothesis­ secretes enzyme that breaks tryptophan down which is necessary for T cell survival (necessary to maintain pregnancy)

53 How do we prevent pregnancy? 1. abstinence ­100 % effective 2. rhythm method­ no intercourse when conception is possible (egg lives 24­48 hrs, sperm 72 hrs) ­80­90% effective 3. condom­ 90% effective 4. IUD ­intrauterine device ­ prevent implantation of blastocyst

http://www.fwhc.org/birth­control/iudinfo.htm

54 5. diaphragm ­ 90% effective

55 6. cervical cap­

http://www.fwhc.org/birth­ control/capinfo.htm

56 7. birth control pills ­ 99% effective, combinations of synthetic progestin and estrogens, stop release of GnRH, prevents ovulation

8. Norplant ­ implanted under skin, alters cervix mucus so sperm can't get in

9. Depo­Provera ­ injection similar to Norplant

10. ­ vasectomy or tubal ligation

57 contraceptive methods

58 Technology advances for genetic diseases

1. amniocentesis

2. chorionic villus sampling

3. ultrasound

4. blood samples

Technology advances for fertilization invitro fertilization

59 Ultrasound

60 4­D ultrasound

http://www.prolifeamerica.com/4D­Ultrasound­pictures/index.cfm?photo=17#photos

61 62