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47 Cards in this Set
- Front
- Back
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Pregnancy
Week 9-birth |
Fetus development: prenatal
stage between 9th week after fertilization until birth |
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Presumptive signs of pregnancy
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• Missed menstrual period with coitus in the
past month • Nausea in morning (“morning sickness”) • Increase in size and tenderness of breasts • Darkening of areola around nipples |
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Probable signs of pregnancy
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Increase in size of abdomen
Missed consecutive menstrual cycles Increase in frequency of urination Positive Hegar’s sign: uterine cervix becomes softer by 6th week of pregnancy Positive pregnancy test |
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What does implantation require?
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Implantation requires a uterus that has
been primed with appropriate amounts of estradiol and progesterone at the right time |
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What does progesterone do in implantation?
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Progesterone also causes the uterus to
secrete protease enzyme that dissolves the zona pellicida surrounding the blastocyst (6 days after conception) |
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How long does blastocyst rest freely in the uterine cavity during implantation?
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Blastocyst rests freely in the uterine
cavity for 2-3 days |
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Implantation penetration in the endometrium
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When zona pellida is completely dissolved,
the inner cell mass end of the blastocyst attaches to the uterine wall and penetrates the endometrium (= implantation) approximately 7 days after fertilization (can be as long as 10 days) A blastocyst poised for implantation releases signaling molecules that interact with endometrium |
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What becomes yolk sac cavity?
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blastocoel
becomes yolk sac cavity |
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How is amniotic cavity formed?
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Blastocyst penetrates further into stroma
and amniotic cavity appears |
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Preembryonic sequence: Day 0
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conception with zygote formation
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Preembryonic sequence: Day 1
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blastomere (2 cells)
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Preembryonic sequence: Day 3
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morula (8-32 cells)
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Preembryonic sequence: Day 4
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early blastocyst
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Preembryonic sequence: Day 5
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late blastocyst
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Preembryonic sequence: Day 6
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blastocyst attaches to endometrium
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Preembryonic sequence: Day 8
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amniotic cavity & embryonic disc form
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Preembryonic sequence: Day 9
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uterine sinusoids develop
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Preembryonic sequence: Day 10
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implantation complete
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Extraembryonic membranes:
amniotic fluid |
8 weeks: 5-10 ml
20 weeks: 250 ml 38 weeks: 1000-1500 ml 40 weeks/term: 500-1000 ml Amniotic fluid is secreted and absorbed at a maximal rate of 300-600 ml per hour |
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When does chorion surround the embryo?
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chorion surrounds the embryo after 1 month of
development |
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What is pumped into the fetal circulation by placental cells (late in pregnancy)?
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late in pregnancy, large protein maternal
antibodies are actively pumped in to fetal circulation by placental cells |
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hemochorial
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directly bathed by maternal blood
like the human placenta (the chorionic villi are directly bathed by maternal blood) |
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Placenta: Week 4
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20% of inner uterine wall
covered by placenta |
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Placenta: Week 20
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50% of inner uterine wall
covered by placenta which weighs 200 gm, while fetus weighs 500 grams |
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Placenta: Week 40
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placenta weight is 700 gms
and has 285 liters of blood that pass through it each day |
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Embryonic development: week 3 ectoderm
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Ectoderm forms dermal layer
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Embryonic development: week 3 endoderm
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Endoderm lines the inner tube which forms
gut/intestine |
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Embryonic development: week 6
eyes |
Eyes become pigmented
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Embryonic development: week 6
ears |
Exterior ears began to form
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Embryonic development: week 7 umbilical cord
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Rapid development of gut tube causes
intestines to protrude into the umbilical cord to produce an umbilical herniation |
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Embryonic development: week 8 major systems
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Brain, spinal cord, and peripheral nerves are
all developed |
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Fetal period: week 9 - birth
organ systems growth rate |
Organ systems established in the
embryonic period continue to develop and differentiate Period of rapid growth |
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vernix caseosa
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protective layer of fatty secretion that occurs during the 6 months
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What's the youngest premature infant that has ever survived?
How heavy? |
Biological age: 21 weeks post conception
Gestational age: 23 weeks the infant was 400 grams |
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When can an ultrasound detect fetal heart rate?
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Ultrasound can detect fetal heart rate by 8
weeks |
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What is evaluated in amniocentesis?
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Cells and amniotic fluid can be evaluated
for chromosomal abnormalities |
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chorionic villus sampling (CVS)
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fetal evaluation technique where needle is inserted through vagina and cervix into uterine
cavity using ultrasound as a guide Chorionic cells are then removed from placenta and analyzed |
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When can dilation and evacuation be performed during pregnancy??
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Performed after 12th week post
conception (after 1st trimester, in 2nd trimester) |
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What is dilation and extraction been also referred to as?
why? is this legal? |
Dilation and extraction referred to as
“partial birth abortion” has been typically performed in the late 2nd trimester and early 3rd trimester Ban on this procedure in USA |
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Dizygotic twin frequency varies by what variables?
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Dizygotic twin frequency varies by ethnicity,
heredity, maternal age, parity, and fertility drugs |
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Monozygotic twin frequency worldwide
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Monozygotic twin frequency worldwide is around 1/250 and is largely independent of ethnicity, age, heredity, and parity
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How is Monozygotic twin frequency effected?
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Monozygotic twin frequency is largely independent of ethnicity, age, heredity, and parity
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What are the Increased risk of monozygotic twins?
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- Delayed transport through the fallopian tube
- Women who have recently been on combination oral contraceptives because they cause decreased tubal motility - Minor trauma to blastocyst during assisted reproductive techniques |
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How will two embryos with
two chorions, two amnions, and one or two placentas develop? |
If division occurs in first 72 hours after conception, before chorion and morula formation,
two embryos with two chorions, two amnions, and one or two placentas will develop |
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How will two embryos with
one chorion, two amnions, and one placenta develop? |
If division occurs between days 4-8 after conception, after chorion and inner cell mass formation,
two embryos with one chorion, two amnions, and one placenta will develop |
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How will two embryos with
a single chorion, amnion, and placenta develop? |
If division occurs after day 8, after chorion and amnion have already formed, two embryos with a single chorion, amnion, and placenta will develop
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How will cleavage be incomplete and conjoined twins be formed?
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If division occurs even later e.g., day 14, that is after the chorion, amnion, and embryonic disk have been formed, cleavage is incomplete and conjoined twins are formed
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