Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Human development block > Implantation,placentation +early embryonic development > Flashcards

Implantation,placentation +early embryonic development Flashcards

1
Q

Define gestational age

A
  • used clinically
  • time zero=first day of last menstrual period
  • expressed in completed weeks plus days
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define embryonic age

A

-used in embryolohy
-Time zero is fertilisation (day 14=ovulation)
-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is implantation?

A

-Begins day 6/7
Complete by day 10 (4 days prior to expected period)
-Three stages: 1.) Apposition 2.) Attachment 3.)penetration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

When is the endometrium receptive?

A

During the implantation window(3 day period) which is from day 7-10

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the different phases of the menstrual cycle?

A
  1. ) proliferative phase
  2. ) Secretory phase split into
    - pre-receptive
    - receptive
    - refractory
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the primitive trophoblast

A
  • Rapidly differentiates into two layers
    1. ) Inner layer composed of mono nuclear cells cytotrophoblastic layer
    2. )Synctiotrophobolast outer layer composed of multinucleated cells

Lacunae (inter-communicating fluid filled spaces appear in the rapidly enlarging trophoblastic mass from the 8th day after fertilisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is haemochorial placentation characterized by?

A
  • This is part of development of the placenta
  • differentation of the endometrium into decidua: enlarged stromal cells and uterine natural killer cells
  • Transformation and opening of the uterine spiral arteries
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Explain the development of the placenta and early embryo as characterized by the end of the second week

A
  • The end of the 2nd week is characterized by the first appearance of chorionic villi
  • Primary villous stems have a central core of cells derived by the proliferarion of the cytotrophoblast
  • The primary villi gradually develop mesenchymal cores,which convert them into secondary villi
  • The mesenchyal cells within the villi differentiate into blood capillaries, thus forming the tertiary villi
  • The vessels from the villi soon become connected with the embryonic heart via vessels that differentiate in the mesenchyme of the chorion and in the connecting stalk
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the transition from a primary to tertiary villus, the time duration and characteristics of each.

A
  • A primary villus is present at 2 weeks, this has a cytotrophoblast core
  • At 3 weeks a secondary villus is present. This has a mesoderm core (has a smaller cytotrophoblast layer)
  • At 4 weeks a tertriary villus is present which contains blood vessels (villous capillary)

Note that they all have cytotrophoblast & synctiotrophoblast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the significance of haemochorial placentation?

A
  • Hemochorial placentation is the time that the fetus has an independent circulation making it an independent being
  • The fetus is still not totally independent, as it is still dependent on the mother for oxygen, sugar, some amino acids, and basic nutrient supply
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Explain the development of the placenta and early embryo beyond the 4th week.

A
  • As the growth continues, the villi on the decidua capsularis (abembryonic) pole degenerate to form the chorion leavae.
  • Villi adjacent to the decidual plate rapidly grow and expand to form the chorion frondosum
  • The chorion frondosum forms the placenta together with the decidual plate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is visible on an USS of a placenta, 6 weeks post conception?

A
  • Chorion laevae: this will be away from the definitive placenta and this bit of the placenta is thin
  • Chorion frondosum: The definitive placenta forms here so this bit of the placenta is thick.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What makes up the outer layer of fetal placenta?

A

-Chorion leavae & chorion frondosum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why must the spiral arteries be dilated?

A
  • Early on, the maternal spiral arteries start to be dilated bu they’re plugged by synctiotrophoblast cells in the centre
  • This protects the embryo from the maternal blood pressure
  • We can use Doppler screening to see if the spiral arteries are open, using ultrasound and looking at the wave forms which are upstream from the spiral arteries
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the characteristics of the uterine arteries of a non-pregnant woman?

A
  • A lot of elastic recoil

- The arteries are narrow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the characteristics of the uterine artery blood flow of a non-pregnant woman?

A
  • Continuous flow throughout the cardiac cycle

- There’s a systolic peak but continuous flow in diastole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the pattern seen in doppler screening in a woman with pre-eclampsia?

A

-You get notching, therefore it looks like non-pregnant uterine arteries

18
Q

When must any interventions for pre-eclampsia take place by?

A
  • 16 weeks
  • definitive placenta forms by about 16 weeks and all transformation of the spiral arteries will be completed by then
  • Therefore,any interventions for pre-eclampsia must be before this
19
Q

What happens to the spiral arteries in pre-eclampsia?

A

Transformation of the spiral arteries is incomplete

20
Q

What are the 2 components of the definitive placenta?

A
  1. ) The maternal portion, formed by the decidual plate, and
  2. ) A fetal portion, made by the chorion frondosum
  • On the maternal side decidual septa extend into the intervillous spaces, dividing placenta into 10-38 cotyledons
  • By the end of the 16th week of pregnancy, the placenta has obtained its definitive form and undergoes no further anatomical modification
21
Q

What different types of multiple pregnancy exist?

A
  1. ) Monozygotic: from one egg, identical; may be monochorionic or dichorionic
  2. ) Dizygotic : from two eggs, non-identical
22
Q

What are the risk factors for having a multiple pregnancy

A
  • age( 35-40yrs)
  • COCP
  • increased BMI
  • family history
  • previous multiple birth
  • parity
  • summer and autumn conceptions
  • smoking
23
Q

What are the different types of mono zygotic multiple pregnancies?

A

1.) Dichorionic: cleavage before implanation; each twin has its own chorionic sac
2,)Mono chorionic or dichorionic
3.)Monoamniotic if cleavage takes place after day 8
-conjoined twinseithout

24
Q

What is a sacricoccygeal teratoma?

A
  • A remnant of primitive streak
  • Benign tumor of the primitive streak
  • Within this you can get any kind of tissue/cell type
  • Occasionally in utero, this has such a big blood supply that it can cause heart failure on the baby
25
Q

What happens a the 5th week of pregnancy?

A

Folding at the longitudinal axis

26
Q

Which week of pregnancy does the brain develop?

A

7th week

27
Q

What is holopresencephaly?

A
  • A CNS congenital abnormality
  • Failure of the forebrain to divide and develop
  • Associated with other midline&facial defects, Trisomy 13
  • Severity varies from not being compatible with life to more mild mental retardation
28
Q

What is Cardiogenesis?

A
  • Determination of mesoderm and neural crest cells for heart formation
  • Growth and differentiation processes to become cardiomyocytes
  • Migration and transformation processes in order to form the heart
  • Day 18-22: Canalization of cardiogenic clusters in the mesoderm results in formation of the paired heart tubes; lateral folding fuses tubes in midline
  • Day 22: Arterial &Venous ends fixed. Bulbous cordis and ventricles grow faster than other regions so tube bends on itself. Sinus venosus, Trunchus arteriosus, Bulbus cordis, ventricle, atrium and cardinal veins also form
29
Q

How and when does a physiological hernia resulting from development of the GI system resolve itself

A

-Loops return into abdominal cavity and physiological hernia resolves by day 56

30
Q

Name some congenital heart defects

A

-Large VSD
perimembranous VSD
-Muscular VSD
-Complete AVSD

31
Q

Name some GI abnormalities

A
  • Omphalocoele: gut still covered in membranes but the baby’s guts are outside
  • Gastroschisis: vascular injury guts are completely outside and unprotected as the membranes are gone
32
Q

When is the period of greatest sensitivity of the embryo and what does this mean?

A
  • 3-8 weeks
  • Peak susceptibity to teratogenesis so best time for intervention
  • Each organ system will also have a period of peak sensitivity
33
Q

When is the period of functional maturation?

A

9-38 weeks

  • fetal membranes in third month
  • Decreasing sensitivity during this period
34
Q

What forms the amniotic sac?

A

The chorion and amnion together

35
Q

What are the different combinations of a monochorionic pregnancy

A
  • Monochorionic-monoamniotic twins are identical twins who share both a placenta and an amniotic sac
  • Monochorionic-diamniotic twins are identical twins who share a placenta but not an amniotic sac
  • On an ultrasound scan the chorionic sac is the bigger black sacs shown
  • The amniotic sac is the greyish smaller sacs shown
36
Q

Are fraternal twins monochorionic or dichorionic

A 
all fraternal (non-identical) twins also are dichorionic twins.
-Chorion sac refers to whether or not you share a placenta-
37
Q

What is sonoembryology

A

Medical exam during pregnancy to detect abnormalities

38
Q

What is the role of the endometrium and in fertility/miscarriages

A
  • Some women that are too fertile(increased receptivity) let abnormal embryos that wouldnt normally do so, implant into their uterus
  • Some women have endometrium that is less receptive than it should be so they become infertile/subfertile
39
Q

What is the corpus luteum?

A

A hormone secreting structure that develops in an ovary after an ovum has been discharged but degenerates after a few days unless pregnancy has begun

  • This continues to synthesize progesterone, which stops the endometrium from breaking down. Therefore Hcg maintains pregnancy
  • If during pregnancy, there’s a low level of Hcg, we know that the pregnancy is likely to be failing in some way
40
Q

What is the deciduate?

A
  • From day 14 onwards, the ‘endometrium’ is called the deciduate as it is now thick, chunky and juicy
  • Has the fetal and maternal tissues firmly interlocked so that a layer of maternal tissue is torn away at parturition and forms a part of the afterbirth.
41
Q

What is the significance of the synctiotrophoblast?

A

Produces vascular endothelial growth factor (VEGF) and stimulates angiogenesis

42
Q

What two transformation processes are crucial in early pregnancy?

A
  • decidualization

- transformation of the spiral arteries

Human development block (35 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions