PPT embryology- test 2 material Flashcards
Fetal Age AKA __________
(conceptional age)
Menstrual age AKA _________
(gestational age)
from 1st day of last period
Refers to the entire products of conception from fertilization onward (the embryo or
fetus and its membranes, placenta)
Conceptus
Extends from the last menstrual period until birth (280 days)
Gestation period
Also called conceptus, first two weeks following fertilization
Pre-Embryo
From the third through the eighth week after
Embryo
11th week (GA) through birth
fetus
An infant less than four weeks old
Neonate
The condition of having a developing embryo or fetus in the body
after the union of the oocyte and spermatozoon.
pregnancy
Clinical Findings of Pregnancy
- Beta hCG (4 weeks GA), some tests may pick up hCG hormone a
little earlier
- Beta hCG (4 weeks GA), some tests may pick up hCG hormone a
- Fetal heart tones (10-12 wks GA)
- Fetal movements (18-20 wks GA)
- Demonstrations of the fetus on ultrasound
- The head of each sperm (acrosome) releases enzymes that begin to
break down the outer, jelly-like layer of the egg’s membrane, trying to
penetrate the egg. - Fertilization of the ovum involves penetration of the sperm through
the corona radiata, zona pellucida, completion of the second meiotic
division of the secondary oocyte, and formation of the zygote.
- Once a single sperm has penetrated, the cell membrane of the egg
depolarizes its electrical characteristics. - This creates a _______________________ that pushes the other sperm far away
from the egg and ensures that only one sperm fertilizes the egg.
cortical reaction
Fertilization usually occurs in the ___________of the fallopian tube.
ampulla
how long after cortical reaction will other sperm die?
with in 48 hours
how long does the fertilization process last?
24 hours
More than _______ of all known
spontaneous abortions result
from chromosomal
abnormalities
50%
out of 100 exposed ova know how many become:
zygotes
implant and produce hcg
abort promptly and persist
stages of fertilization and onward
fertilization
zygote
cleavage
morula
blastocyst
how long are eggs and sperm viable for
eggs viable for 12-14 hours
sperm for 24-72 hours
formed by union of oocyte and sperm cell
zygote
period of fairly rapid mitotic divisions of the zygote following fertilization
- 2 cell state at about 24 hours
-4 cell stage at about 48 hours
-8 cell stage at about 72 hours
cleavage
solid ball of cells that are at least 16 cells big or more
zone pellucida outer protective shell like covering
approx 3 days after fertilization
morula
fluid enters the morula (about 100 cells big) and separates the embryonic cells (blastomeres) into two layers which is what stage
blastocyst
fluid enters the morula (about 100 cells big) and separates the embryonic cells (blastomeres) into two layers
what is the 2 layers
1) outer layer or TROPHOBLAST, consists of large flattened cells which eventually become the chorionic membrane and fetal contribution to the placenta; which will secrete hcg to prompt the corpus luteum to continue secreting progesterone in order to maintain the endometrium
2) inner cell mass- a cluster of small rounded cells that becomes the embryonic disc, amnion, cord, and yolk sac.
how long does the blastocyst remain in endometrial cavity before attaching to wall
approx 2 days
how many chromosomes does a zygote have?
46- 23 from both parents
Early chorionic villi develop and begin to produce ______________________
Described as thread-like vascular projections arising off the chorion
human chorionic gonadotropin (hCG)
Embryonic disk lies between the amniotic cavity and the ____________
yolk sac
by what week can a gestational sac usually be seen by TV ultrasound
4.5 weeks
By 5 weeks, the chorionic cavity is well developed and contains fluid- sonographically called the ___________________.
gestational sac
what envelopes the umbilical cord
amnion
what connects the yolk sac to the embryo
yolk stalk
what happens with the chorionic cavity after the amniotic cavity gets so big?
it obliterates it
is the portion of the endometrium that underlies the implantation site
where embryo implants and placenta grows
Decidua basalis:
includes the remaining endometrium of the uterus and the cervix
Decidua parietalis:
is a thin portion of the endometrium that overlies the conceptus, facing the uterine cavity.
Decidua capsularis:
after fertilization occurs then _________________ starts
embryogenesis starts
how long does embryogenesis last
from fertilization to the end of 10th week of gestational age (LNMP)
rapid growth can be called
differentiation
lack of folic acid can contribute to ____________
spina bifida
Three primordial tissues:
Endoderm
Mesoderm
Ectoderm
During the __________ week (GA), the primary germ layers form along the embryonic disk
fifth
Gives rise to the functional linings of the digestive, respiratory, and urogenital systems and the associated glands.
endoderm
Forms smooth and striated muscle, bone, and most of the cardiovascular system; is a source of blood cells, bone marrow, and reproductive and excretory organs.
mesoderm
Gives rise to skin and the nervous system (central and peripheral), the retina of the eye, and various other structures.
ectoderm
The primitive heart tube is forming.
Vasculature begins to develop in the embryonic disc.
A neural groove (future spinal cord forms over the notochord with the brain bulge at one end).
Neural crest becomes peripheral nervous system (PNS)
Neural tube becomes central nervous system (CNS)
Somites become spinal vertebrae
if the anterior neural pore fails to close than the baby will be born with _______________
anencephaly
if the posterior neural pore fails to clos then the baby will be born with __________
spina bifida
ask if we need to know all of this
how long is the embryo in week 5
4mm(1/8 inch)
it begins to curve into a c shape
what happens in week 5 GA
the heart begins to beat in a regular rhythm
the neural tube closes
ears begin to form
The first traits of the lungs and liver appear.
Buccopharyngeal membrane ruptures. This is the future mouth.
Cystic diverticulum, which will become the gallbladder, and dorsal pancreatic bud, which will become the pancreas appear.
The rectal and urinary passageways become separated.
Anterior and posterior horns differentiate in the spinal cord
Spleen appears
how long is the embryo in week 6 GA
8mm (1/4 inch)
what happens in week 6 GA
*eyes developing,
*nasal pits form,
*brain divides into 5 VESICLES,
*leg buds form, hands form as flat paddles on the arms, and
*rudimentary blood moves through primitive vessels connecting to the yok sac and chorionic membranes
how long is the embryo in week 7 GA
13mm (1/2 inch)
what happens in week 7 GA
lungs begin to form
* brain continues to develop
* arms and legs have lengthened w/ foot and hand areas distinguishable
* gonadal ridge begins to be perceptible
* the lymphatic system begins to develop
how long is the embryo in week 8 GA
18mm (3/4 inch)
most common benign form of Gestational Trophoblastic Neoplasia (GTN) is ______________
hydatidiform molar pregnancy
2 types of hydatidiform
partial and complete
image of complete molar
image of partial molar
An invasive mole is a hydatidiform mole that penetrates the ____________ wall of the uterus .
muscular, myometrium
_____________ is a malignant form of gestational trophoblastic disease GTD
Choriocarcinoma
The ______________________ is a subcutaneous fluid-filled space normally seen between 11-14 weeks GA.
The measurement of this space is used as a screening for Trisomy 21 and other neural and chromosomal conditions.
nuchal translucency (NT)
A good transvaginal, sagittal section of the fetus must be obtained, with the fetus horizontal on the screen. The correct view is a clearly visualized fetal profile.
The fetus should be in a neutral position, with the head in line with the spine, not hyper-extended or flexed.
The minimum fetal crown-rump length should be 45mm and the maximum 84mm.
The optimal gestational age for measurement of fetal nuchal translucency is 11-13 weeks.
The magnification should be such that the fetus occupies at least three-quarters of the image.
NT scanning protocol
what can increased nuchal translucency thickness indicate
trisomy 21
what should the Nuchal Translucency NT measurement be?
under 3mm because anything greater is concern for aneuploidy
Non-Invasive Prenatal Testing (NIPT)
A sample of the mother’s blood is taken to evaluate “free fetal” DNA for chromosomal abnormalities.
Mainly used to look for trisomies 13, 18, 21, and sex chromosome abnormalities.
This test is 80-99% accurate depending on the specific abnormality.
Cannot screen for all known chromosome disorders.
Results are usually available in 1-2 weeks
Sonographic Appearance of the Gestational Sac- Double Decidual Sac Sign (DDSS)
2 sides of the placenta
maternal side(decidua basalis)
fetal side (chorion frondosum)
The placenta is firmly attached by ________
villi
image to study
what produces Human Chorionic Gonadotropin- hCG
produced by chorionic villi and placenta
when does Human Chorionic Gonadotropin- hCG peak?
at the 10th gestational week (100,000mIU/mL)
what happens to Human Chorionic Gonadotropin- hCG after the 10th week?
it declines and levels outa about 18 weeks (5,000 mIU/mL)
what are the 2 common hCG tests?
qualitative and quantitative
difference between qualitative and quantitative hcg
qualitative detects hcg in blood
quantitative measures the amount actually present in the blood
what level should hCG levels be to see gestational sac TV and TA
TV 500-1500 IU/L
TA 1800 IU/L
hCG levels double every ______________
2 days
when is the most accurate time for dating
1st trimester
when should you include BPD?
around 12 week mark
3 measurement methods of dating a pregnancy
MSD - mean sac diameter
CRL- crown rump length
BPD- bipariteal diameter
how to calculate MSD (mean sac diameter)
length + width + height / 3 = MSD
how to calculated menstrual age from MSD
MSD (mm) + 30= menstrual age in days
when can a gestational sac be detected
TA- 5 weeks
TV- 4.5 weeks
what is the yolk sac responsible for
Provision of nutrients to the developing embryo
Hematopoiesis
Development of embryonic endoderm (forms primitive gut)
diameter of yolk sac should not exceed _______
6mm
how big in the MSD when you can see yolk sac
TA- 20mm
TV- 12mm
Cardiac activity should be identified by _____ weeks and as early as _______ weeks
6 weeks
5.5 weeks
how fast is the heart beat before 6 weeks
100-115 bpm
how fast is the heart beat after 6 weeks
120-160 bpm
when should cardiac activity be evident using MSD
TA- 25mm
TV- 16mm
when will cardiac activity be evident using CRL transvaginally
7mm
most accurate measurement for dating
CRL crown rump length
normal pathalogy
Thin hyperechoic line between the embryo and the yolk sac
amnion
Many “screening” examinations are performed at _________ wks for dating and to R/O anomalies
18-20
