frolich, human anatomy, reproduction, early dev., pregnancy reproduction, early development,...
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Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Reproduction, Early Development, Pregnancy
l 1. From 2 cells• …a 3-layer embryo• …a yolk sac, amniotic cavity, chorionic
cavity• …a placenta
l 2. Pregnancy and Childbirth • Changes to female anatomy• Labor and birth
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Ovulation 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
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Ovulation and Meiosis
Fig. 24.15
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Spermatogenesis 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 tubulerete testis head/body/tail epididymis vas deferens (through spermatic cord around bladder) urethra
Seminiferous tubulerete testis head/body/tail epididymis vas deferens (through spermatic cord around bladder) urethra
Fig. 24.3
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Sustentacular cells 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 Fig. 24.4
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
First week of development
Oocyte(fertilization)zygote4-cell stage (2 days) morula (ball)blastocysteinner cell mass (embryo)
Trophoblast (extraembronic membranes)
From oocyte to blastocyst
Fig. 3. 3
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Implantation
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 Two layers
– Stratum basalis– Stratum functionalis
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.
Fig. 24.18
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Endometrium and menstrual
cycle
Fig. 24.19
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Endometrium and menstrual
cycle
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 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
Implantation with ICM towards uterine wall Trophoblast
– Cytotrophoblast (cells around ICM)– Synctiotrophoblast (synctium of cells that becomes placenta)
Meanwhile…back in the embryo
Fig. 24.25
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Placenta formation
Lacunae form within synctiotrophoblast--maternal blood fills these spaces
Vili form with embryonic capillaries down middle
Fig. 24.25
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Placenta formation
Villi bathed in maternal blood in lacunae--exchange of nutrients, O2, CO2
After 13 weeks, full placenta--pancake-shaped organ.Fig. 24.25
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Other extraembryonic tissues 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
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!!
Fig. 3. 4Animated movie of fetal deveopmenthttp://www.cvillepregnancy.org/fetal.html
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Pregnancy--changes in female anatomy 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
Postural changes to compensate for anterior weight
Breasts enlarge--first milk production
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Birth Stage 1. Dilation Stage
– Ligaments loosen– Cervix dilates
Stage 2. Expulsion– Baby moves through pelvic girdle--head is rotated
90 degrees– Floor of pelvis
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
Stage 3. Placenta.– Detaches and is expulsed within one hour.
Frolich, Human Anatomy, Reproduction, Early Dev., Pregnancy
Fig. 24.27