b206ch26

Chapter 26: Reproduction and Development..Farabee..hard to beat textbook figures.

Lab Ex 15 is not done, but: Sea Urchin Development video/anim, echinoderm,

Biology and Society: Rise of the Supertwins fig 1 has septuplets

Risks associated with using fertility drugs is covered below, with reproductive technologies

Unifying Concepts of Animal Reproduction

Asexual: budding, fragmentation fig 2, parthenogenesis: aphid, Parthenon, rotifer (below blue o).
Saves energy, but clone. List, Kimball
Hermaphrodites can be sequential (fishy) or simultaneous: fig 3, & a fish & a slug,
human embyos: bipotential gonad & male & female ductwork until the sex is determined (~ week 6)
External fertilization is most aquatic species: anemone, anatomy, fish, frog amplexus..
Internal fertilization is terrestrial animals: insect mating, & aquatic mammals
Sexual reproduction is more adaptive than asexual when environment is changing.

CHECKPOINT p 562
1. What is the most important genetic difference between asexual & sexual reproduction?
2. Describe three types of asexual reproduction
3. What is the advantage of sexual reproduction?

Human: hypothalamus > GnRH > ant. pituitary > FSH, LH > gonad: E & P, or T

Female: fig 4-6: ovaries, fimbrae, oviduct, uterus, cervix, vagina, clitoris, labia
Male: fig 6, testes, epididymis, vas deferens, seminal vesicles, prostate, urethra, penis
Gametogenesis: egg & sperm formation
Oogenesis, egg formation fig 7, all oocytes begin meiosis before birth. ovary
at maturity: one egg/month is developed, & released @ ovulation, ovaries take turns:
primary follicle > secondary (fluid space) > rising estrogen > LH surge > ovulation >
corpus luteum forms, & secretes E & P, > if corpus albicans > menstruation
spermatogenesis: fig. 8, at maturity few million/day: testis histology
spermatogonia > spermatocyte > spermatid > sperm.
Sertoli cell controls & secretes inhibin, interstitial cell (Leydig) secretes testosterone
Regulation
Male: hormonal control begins in brain, hypothalamus
The events of the female reproductive cycle = fig. 9, wiki, Another

Kimball: hormones: hypothalamus: GnRH > FSH, & LH which causes ovulation

ovaries release E to develop & maintain ductwork, & E & P after ovulation to enable implantation
If a pregnancy occurs > implanted blastocyst secretes HCG (in urine is pregnancy test)
> ovaries continue secretion of E & P > uterus wall is maintained
> embryo develops > placenta takes over secretion of E & P

CHECKPOINT p 569
1. where does the fetus develop?
2. correct sperm route?:
epididymis, testis (seminiferous tubules), seminal vesicles?, prostate, urethra, ureter, vas deferens
3. one primary oocyte > ? secondary > ? eggs (ova)
4. what hormonal events trigger: menstruation? ovulation? puberty? spermatogenesis? oogenesis?

Reproductive Health, on test only as it illustrates normal biology

Contraception: rhythm method?, & oral contraceptive? > lowers FSH, so?
Sexually Transmitted Diseases - not on test, would you trust him?

CHECKPOINT p 572
1. male equivalet of tubal ligation in females?

Human Development: Carnegie Stages, same-wiki, IU anim, DiscoveryCh

Fertilization, fig 11-13, many sperm break down barriers around egg: cells & zona pellucida.
Sperm's acrosome contains digestive enzymes, & only one nucleus enters egg.
Then barriers form: blocks polyspermy.
Basic Concepts of Embryonic Development = take one step at a time, NO blueprint
zygote > cleavage > morula > blastocyst > gastrula, fig 14, 16 & 17
resource: mammals cleave like a fish, but gastrulate like a reptile & bird =
along a line in the ectoderm: the primitive streak
reptiles developed this way to deal with heavy yolk - impossible to cleave right through
Gastrulation resource,
Gastrulation produces: ectoderm, mesoderm, & endoderm: all produce epithelia, but
only ectoderm produces nerve, & mesoderm produces connective tissues & muscle
All any cell knows is what to do next = induction

Induction occurs throughout development, produces all complex structures:
= adjacent cells talk to each other & cooperate to produce form

NOT the same meaning as inducing childbirth
apoptosis, fig 15, is part of morphogenesis
yellow notocord (mesoderm) induces green neural tube (ectoderm): fig is chick embryo
fig 19a, eye = induction between pre-retina & pre-lens (ectoderm induces ectoderm!)
every structure in the embryo is the product of induction
the embryo at first digests the endometrium to grow fig 16, implantation
the trophoblast fig 17, (pre-placenta) secretes human chorionic gonadotropin
= pregnancy test > to keep ovary producing estrogen & progesterone to maintain endometrium
in reptiles, birds & mammals, fig 18 bold, there are 4 extraembryonic membranes, human,
1) amnion: fluid bag protects embryo, amniocentesis
2) yolk sac: stores food in eggs, in mammals forms first germ cells, & blood cells
3) allantois: stores wastes in shelled eggs, in mammals forms part of umbilical cord
4) chorion: lines egg shell, in mammals forms part of the placenta & secretes hormones.
Placenta becomes main source of estrogen & progesterone (scroll to figure).
Development by trimester = to weeks 13, 26, 39. also too detailed,

First trimester:

fig 19: embryo first 8 wks: forms organs, limb buds, tail, early on vertebrates

Second & Third trimesters

Next 7 months fetus grows, fig 19, becomes more like infant

estrogen induces oxytocin receptors on muscle cells of myometrium, fig 21
& stress on mother > rising CRH > ACTH > cortisol > rising oxytocin & receptors
fig 21: oxytocin, prostglandins, & decreased progesterone cause contractions in parturition
The three stages of labor: dilation, expulsion, placental delivery, fig 22. Induction
relaxin helps to soften ligaments & joints
Nursing
oxytocin also causes milk let down in .
milk synthesis/secretion = prolactin's role

CHECKPOINT p 578
In fertilization two haploid ? fuse to form a diploid ?
Put in order: organ formation, fertilization, gastrulation, cleavage
Would you expect the cells of the blastocyst to get more or less oxygen than the zygote? Why?
Why should a woman trying to conceive try to avoid drugs, alcohol, & nicotine
Why is it important for the embryo that high levels of E & P are maintained in the mother's blood?
Why isn't a newborn immediately susceptible to numerous infections?

Reproductive Technologies (not on test unless follows from normal biology)
Causes of infertility, & treatments fit the cause.
In vitro ( = in glass) fertilization, follows producing several eggs, induced by FSH injections
Problems created by reproductive technologies: multiple births, what else?

CHECKPOINT p 580
1. Name of procedure to make test-tube baby?
2. Distinguish between infertility & impotency
3. How can five people be involved in creating one baby? chimera, image

Evolution Connection: Menopause and the Grandmother Hypothesis