Reproductive Biology

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Reproductive Biology
Mechanisms of Asexual Reproduction
Budding
Fission
Parthenogenesis
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Asexual Reproduction
Sexual Reproduction
Create new individuals whose genes come from one
parent (no fusion of egg sperm)
Create new individuals by fusion of haploid
gametes (meiosis)
gamete (n)
gamete (n)
ovum (n)
spermatozoa (n)
relies mainly on mitotic division
zygote (2n)
increase genetic variability
enable animals living in isolation to reproduce
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Whiptail lizard
Parthenogenesis Development of an egg without
fertilization
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Hermaphroditism One organism carries both male
and female reproductive organs and gametes
Earthworms mating
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Go to biology.berkeley.edu/bio1a for movies
on the reproductive system. (In the Course
Information frame, look under the Extra
Resources tab.)
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Reproductive anatomy of the human male
thick voluminous fluid mucus fructose
alkaline
accessory glands
thin milky fluid anticoagulant citrate
Penis
Clear mucid fluid neutralize acidic urine
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4
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2
1
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Reproductive anatomy of the human female
Secrete mucus for lubrication
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Reproductive anatomy of the human female (contd)
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GONADAL STEROID HORMONES
HO
CHOLESTEROL
(precursor)
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Regulation of sexual characteristics in the female
Gonadotrophin-Releasing Hormones
Gonadotrophins
corpus luteum
ovary
ovulation
Estrogen Progesterone
Gonadal Steroids
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Regulation of sexual characteristics in the male
Gonadotrophin-Releasing Hormones
Gonadotrophins
Androgen production
testis
Spermatogenesis
Testosterone
Gonadal Steroids
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In MALE
(GRH)
FSH - stimulates maturation of spermatogonia
(gonadotrophins)
LH - stimulates interstitial cells to secrete
testosterone
(interstitial cells)
Barry Bonds??
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n ploidy 2n diploid 1n haploid
c content of nuclear DNA ( of chromatids)
2n, 2c
(goes on throughout adult life)
Duplicate DNA
2n, 4c
1n, 2c
1n, 1c
1n, 1c
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Regulation of sexual characteristics in the female
Gonadotrophin-Releasing Hormones FSH-RH and LH-RH
Gonadotrophins Follicle Stimulating Hormone
Luteinizing Hormone
corpus luteum
ovary
ovulation
Estrogen Progesterone
Gonadal Steroids
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In FEMALE
FSH - stimulates maturation of follicle (of sperm)
LH - stimulates corpus luteum to secrete
progesterone (interstitial
cells/testosterone)
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Oogenesis in the female ovary
(no further division after birth)
2n, 2c
(arrested at this stage until puberty)
2n, 4c
1n, 2c
1n, 1c
1n, 1c
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Ovulation
Ovarian Cycle
(corpus luteum)
Female reproductive cycle in the absence of
fertilization
Gonadotrophins
Ovarian changes
Ovarian changes
Uterine wall
Uterine wall
Menstrual Cycle
(or estrus cycle in most mammals)
Estrogen
Gonadal Steroids
Progesterone
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FOLLICULAR PHASE
(rise in FSH results in follicle maturation --gt
rise in estrogen)
of estrogen
ovulation
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Late follicular stage and
(characterized by surge in FSH minor surge in
LH)
OVULATORY PHASE
of estrogen
(anterior pituitary)
ovulation
Surge of LH
Ovulation
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SECRETORY PHASE
(LUTEAL PHASE)
(characterized by high levels of estrogen
progesterone)
ovulation
Maintain uterine lining in secretory state
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Ovulation
Ovarian Cycle
Female reproductive cycle in the absence of
fertilization
Gonadotrophins
Ovarian changes
Uterine wall
Menstrual Cycle
Estrogen
Gonadal Steroids
Progesterone
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Female reproductive cycle when fertilization
occurs
prior to implantation
HCG
HCG - Human Chorionic Gonadotrophin (structurally
similar to LH) secreted by developing embryo
after implantation
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Fertilization and Implantation
It takes about 4 days from ovulation to the
uterus about another 1-4 days for implantation
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The Human Embryo
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Stage 12 30 Days (3-5 mm) Caudal neuropore
closes. Four pharyngeal arches visible. Upper
limb buds appear. Secondary neurulation
commences. Lung bud appears. Cystic primordium
dorsal pancreas becomes distinguishable.
Stage 11 29 Days (2.5-4.5 mm) The rostral
neuropore closes and the otic pit is still open.
The optic vesicles develop and sinus venosus
begins. The mesonephric duct tubules appear.
Staging from http//virtualhumanembryo.lsuhsc.edu/
HEIRLOOM/Stages/HEP.htm
Stage 16 38 Days (8-11 mm) Retinal pigment
is visible. Nasal sacs face ventrally. Foot
plate appears. Epiphysis cerebri develops.
Neurohypophysial evagination is visible. Lobar
bronchi are evident.
Stage 14 33 Days (5-7 mm) Lens pit appears.
Endolymphatic appendage becomes defined. Upper
limb buds are elongated tapering. Optic cup
develops. Adenohypophysial pouch is defined.
Ureteric bud appears.
Stage 18 44 Days (13-17 mm) Body is more
cuboidal. Digital plate of hand is notochord. Toe
rays begin to appear. Oronasal membrane develops.
1 to 3 semicircular ducts present in internal
ear. Septum secundum foramen ovale are distinct
in heart.
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Stage 19 46 Days (16-18 mm) Trunk is
elongated straightening. Limbs extend nearly
directly forward. Toe rays are prominent, but
interdigital notches have not yet appeared.
Olfactory bulb develops. Cartilaginous otic
capsule is visible. Posterior epithelium of
cornea begins to develop.
Stage 20 49 Days (18-22 mm) Upper limbs are
longer bent at elbows. Nerve fibers reach optic
chiasma. S-shaped renal vesicles are visible in
metanephros.
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Stage 22 53 Days (23-28 mm) Eyelids
external ears better developed. Adenohypophysial
stalk is now incomplete. Scleral condensation is
visible. Some large glomeruli are present in
metanephros.
Stage 23 56 Days (27-31 mm) Head is more
rounded. Limbs are longer better developed.
Humerus presents all cartilaginous phases. Bone
collar of humerus has not yet been eroded through
completely. Secretory tubules of metanephros
become convoluted, numerous large glomeruli are
present.
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Placentation Development of the Fetus
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Sexual Development in the Human Embryo
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Early Development of External Genitalia
Bipotential stage (6 week fetus)
10 week fetus