Term
| The ___ stage is from fertilization to 8 weeks. The ___ stage is from 9 weeks to birth |
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Definition
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Term
| The ___ is a fertilized egg. The ____ is the embryo + placenta. |
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Definition
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Term
| A "full term" human pregnancy ranges from __ - __ days, with a modal length of __ days. |
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Definition
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Term
| Fertilization age vs. gestational age |
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Definition
Fertilization age - uses the event of fertilization as time zero (38 weeks)
Gestational age - uses the date of mother's last period as time zero (40 weeks) |
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Term
| The most critical stages of development occur when? |
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Definition
| first trimester (13 weeks) |
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Term
| The length in centimeters from the top of the baby's head to the bottom of the buttocks. What is a normal length for 8 weeks? for 38 weeks? |
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Definition
Crown Rump Length.
8 weeks - 3cm
38 weeks - 35 cm
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Term
| What is a habitual abortion? |
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Definition
| 3 consecutive spontaneous abortions |
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Term
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Definition
| spontaneous abortion before the middle of the second trimester |
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Term
| When an egg is first fertilized, the zygote undergoes repeated divisions into smaller cells called _____. At the 12-32 cell stage, the structure is called a _____. |
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Definition
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Term
| what are the three parts of the blastocyst and what does each turn into? |
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Definition
outer cell layer (trophoblast) becomes placenta
inner cell layer (embryoblast) becomes embryo
Fluid filled cavity is blastocoel |
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Term
| It takes about ___ days to form to morula and about ___ days until the morula enters the uterine cavity and becomes the blastocyst |
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Definition
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Term
| Around day ____, the blastocyst implants in the endometrium. Describe the course of events. |
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Definition
Day 6-7.
The embryoblast implants, the trophoblast differentiates into the syncyntiotrophoblast and the cytotrophoblast. |
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Term
| How does the morning after pill work? |
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Definition
| large doses of estrogen and/or progestins accelerate the passage of cleaving zygote along the uterine tube. interferes with the preparation of the endometrium |
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Term
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Definition
| causes local inflammatory reaction which interferes with the development of the endometrium |
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Term
| The embryo typically implants in which part of the uterine wall? What happens if it implants in a different part? |
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Definition
posterior superior
ectopic pregnancy - the embryo implants in a location other than the uterus (usually uterine tube, but sometimes the ovary, abdominal cavity, or cervix) |
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Term
| What is placenta previa and how is it fixed? |
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Definition
| When the embryo implants in the lower part of the uterus towards the cervix and the placenta obstructs the cervical canal. During birth, the placenta can tear and the mother can die from hemorrhage. This is diagnosed by ultrasound and the baby is delivered via c-section. |
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Term
| How does invitro fertilization work? |
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Definition
| Eggs are taken from the mother and fertilized in a petri dish. The cells are allowed to reach the 4-8 cells stage and then they are injected into the mother. At this point, the mother's body has to decide to implant the zygote into the uterine wall. |
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Term
| During the second week, the embryoblast differentiates into two layers: |
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Definition
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Term
| Blood/nutrients enters the embryo through the ______ (layer). This layer also produces Human chorionic gonadotropic (hCG) which maintains the viabillity of the corpus luteum |
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Definition
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Term
| How do pregnancy tests work? |
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Definition
| They detect hCG in the mother's blood beginning at day 10. |
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Term
| Low hCG in the blood suggests what? High hCG suggests? |
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Definition
low - may predict a spotaneous abortion or ectopic pregnancy
high - may indicate multiple pregnancies or hydatidiform mole (abnormal placenta) or gestational trophoblastic neoplasia (malignant tumor of trophoblast) |
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Term
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Definition
appearance of the primitive streak
Gastrulation - differentiation of germ layers
Development of notochord - beginning of vertebral column |
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Term
| The ___ is a lear band of thickened epiblast that begins at the ___ end of the embryo and grows ____. The cranial end forms the _____. Cells migrate through this to form the ____ layer. |
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Definition
Primitive streak. Begins caudal, grows cranially.
Forms the primitive knot (or node).
Forms the mesodermal layer |
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Term
| Remnants of the primitive streak may persist and give rise to a _____. |
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Definition
| sacrococcygeal teratoma (a big tumor on the caudal end of the infant). usually happens in girls. |
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Term
| How is the notochord formed? |
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Definition
| Mesenchymal cells from the primitive knot migrate to the prechordal plate to form the notochordal process in the midline. The notochord develops from this process. |
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Term
| What does the notochord eventually become? What does the prochordal plate become? |
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Definition
notochord: nucleus pulposus
prechordal plate: mouth |
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Term
| What does the endoderm become? |
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Definition
epithelial lining of GI and lower resp tract
all ducts entering GI tract
Urinary bladder
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Term
| What does the ectoderm become? |
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Definition
Nervous system
Epidermis
Lining of mouth and anus
Sensory organs (eyes) |
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Term
| What does the mesoderm become? |
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Definition
| muscle, bone, cartilage, blood, dermis, kidneys, ovaries, testes, lining of body cavities |
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Term
| Week 3 differentiation. The epiblast becomes the ___, ___, and primitive streak. The primitive streak then becomes the ___, ____, ____, and ____. |
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Definition
ectoderm of amnion, embryonic ectoderm
extraembryonic mesoderm, embryonic mesoderm, notochordal process, embryonic endoderm |
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Term
| Week 3 differentiation. The hypoblast becomes the ____., which becomes the ____. |
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Definition
| endoderm of umbilical vesicle. extraembryonic mesoderm |
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