Transcript Reproduction, Early Development, Pregnancy

Reproduction, Early
Development, Pregnancy
1. From 2 cells
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…a 3-layer embryo
…a yolk sac, amniotic cavity, chorionic
cavity
…a placenta
2. Pregnancy and Childbirth
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Changes to female anatomy
Labor and birth
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Ovulation
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Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
1o oocytes arrested in
Meiosis I in female fetus
After puberty, 1 primary
oocyte/month completes
Meiosis I as follicle matures
Follicle ruptures-ATTENTION--CELL LOOSE
IN CELOM
Oocyte enters Fallopian tube
If fertilization occurs, Meiosis
II occurs and oocyte
becomes ovum
Ovulation and Meiosis
Fig. 24.15
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Spermatogenesis
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Fig. 24.3
Sperms form in walls of
seminiferous tubules
Spermatogenic cells within
sustentacular cells
Meiosos proceeds as
spermatocytes move
towards lumen (4 sperm
from each spermatocyte)
Seminiferous tubulerete
testis head/body/tail
epididymis vas deferens
(through spermatic cord
around bladder) urethra
Seminiferous tubulerete testis head/body/tail epididymis 
vas deferens (through spermatic cord around bladder) urethra
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
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Form thick epithelial
lining of
seminiferous
tubules
Tight junctiones
between keep
sperm proteins from
entering bood
Produce testicular
fluid which helps
move sperm
Concentrate
testosterone to
stimulate sperm
production
Produce inhibin
which slows sperm
production
Sustentacular cells
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Fig. 24.4
First week of development
From
oocyte to
blastocyst
Fig. 3. 3
Oocyte(fertilization)zygote4-cell stage (2 days)
morula (ball)blastocysteinner cell mass (embryo)
Trophoblast (extraembronic membranes)
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Implantation
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Endometium ready for implantation
Blastocyst implants with ICM against uterine wal
Ectopic pregnancy--implantation outside built-up
endometrium (potential for bleeding since embryo
stimulates vascularization)
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Endometrium
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Fig. 24.18
Two layers
– Stratum basalis
– Stratum functionalis
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Stratum functionalis builds up
each month in response to
ovarian hormones
Uterine glands secrete
glycoproteins--nutrients for
potential zygote--into uterine
cavity
At menstruation, functional layer
self-digests, spiral arteries kink
and constrict so cells die.
Just before menstrual flow
starts, spiral aa. Open wide,
capillaries burst and functional
layer sloughs off.
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Fig. 24.19
Endometrium
and menstrual
cycle
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
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Menstrual Phase (Days 1-5): Sloughed
Functional layer of endometrium expelled
through vagina as menstrua flow
Proliferative phase (Days 6-14): In
response to estrogen from growing
ovarian follicle, new functional layer
elaborates
Ovulation (about Day 14)
Secretory phase (Days 15-28):
– Spiral aa. Elongate and coil
– Uterine glands secret glycoproteins
– More estrogen (and progesterone) from
corpus luteum
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If pregnancy, secretory phase continues
due to embryonic estrogen production
If no pregnancy, corpus luteum
degenerates, estrogen drops leading to
menstruation
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Endometrium
and menstrual
cycle
Meanwhile…back in the embryo
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Implantation with ICM towards uterine wall
Trophoblast
Fig. 24.25
– Cytotrophoblast (cells around ICM)
–Human
Synctiotrophoblast
(synctium
of cells that becomes placenta)
Frolich,
Anatomy, Reproduction, Early
Dev., Pregnancy
Placenta formation
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Fig. 24.25
Lacunae form within synctiotrophoblast--maternal
blood fills these spaces
Vili form with embryonic capillaries down middle
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Placenta formation
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Villi bathed in maternal blood in lacunae--exchange of
nutrients, O2, CO2
Fig. 24.25
After 13 weeks, full placenta--pancake-shaped organ.
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Other extraembryonic tissues
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Cellular trophoblast forms
amnion, yolk sac
Fetal cells shed into
amniotic cavity which fills
with fluid from fetal
kidneys extreted through
ureter, bladder, urethra
Amniocentesis--sample of
amniotic fluid taken with
hypodermic needle
Part of yolk sac “sucked”
into embryo to form
endermic bladder
Fig. 3.4
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Embryo proper
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ICM forms hypoblast (yellow-becomes endoderm) and
epitblast (blue--becomes
ectoderm)
See handout for all adult
derivatives of embryonic
tissues--HOW FAR WE’VE
COME!!
Animated movie of fetal deveopment
http://www.cvillepregnancy.org/fetal.html
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Fig. 3. 4
Pregnancy--changes in female anatomy
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Shift in organs
– Bladder, rectum pushed superiorly,
squeezed--change in urination,
defecation patterns
– Stomach compressed--eat more
often, less at each meal
– Immune response may change
appetite to avoid possible poisons for
fetus
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Postural changes to compensate
for anterior weight
Breasts enlarge--first milk
production
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Birth
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Stage 1. Dilation Stage
– Ligaments loosen
– Cervix dilates
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Stage 2. Expulsion
– Baby moves through pelvic girdle--head is rotated
90 degrees
– Floor of pelvis
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Kegel exercises
Perineal support
Avoid ripping or episiotomy
– Baby skull--sutures not fused, bones can be slide
on top of each other giving pointed look
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Stage 3. Placenta.
– Detaches and is expulsed within one hour.
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Fig. 24.27
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy