Brainscape's Knowledge GenomeTM

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


See full index

Medicine Year 1 Semester 1 - Part 2 > Early Embryonic Development > Flashcards

Early Embryonic Development Flashcards

1
Q

Briefly describe the formation of an embryo

A

Sperm fuses with the ovum
This forms a zygote
Blastocyst
Bi laminar disc
Tri laminar disc
Embryo

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

What forms the zygote ?

A

Spermatozoon and secondary oocyte (ovum)

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

What is the function of the acrosome of the sperm ?

A

Contains enzymes required for the penetration of the zone pellucida of the oocyte.

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

Where are 2ndary oocytes found ?

A

In the ovary, arrested in metaphase 2 of meiosis 2

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

Describe what the cytoplasm of the oocyte is surrounded by.
(inner to outer)

A

Plasma membrane
Zona pellucida
Corona radiata

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is ovulation ?

A

The discharge of usually a single secondary oocyte from the ovary as a result of increase in luteinising hormone (LH)

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

What type of cells are found in the corona radiata ?

A

Cumulus oophorus cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

When is Meiosis 2 completed ?

A

When the secondary oocyte is fertilised
The oocyte matures to become ovum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the steps in ovulation

A

The ends of the uterine tubes come into close contact with the ovary during ovulation.

Fimbriae of uterine tubes ‘sweep’ the ovulated ovum into the uterine tube.

Peristaltic waves of uterine tube musculature bring the 2ndary oocyte into the ampulla of the uterine tube.

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

What is fertilisation ?

A

Fusion of the haploid sperm and haploid oocyte to form a diploid zygote.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where does fertilisation usually take place ?

A

Ampulla region of the uterine tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What must spermatozoa undergo to acquire fertilisation capability ?

A

Capacitation
Acrosome reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe spermatozoon penetration

A

Phase 1 : Capacitation (passing through the corona radiata)

Phase 2 : Acrosome reaction (penetration of the zone pellucida)

Phase 3 : Penetration of the oocyte membrane by one spermatozoon, which loses its own plasma membrane.

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

What enzyme penetrates the corona radiata ?

A

Hyaluronidase
Interaction with ZP3 receptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe fertilisation

A

Penetration of corona radiata - by hyaluronidase

Interaction with ZP3 receptor

Acrosome reaction - digests zone pellucida

Membrane fusion

Completion of oocyte meiosis

Release of the contents of cortical granules :

  • Degradation of ZP3 to prevent second penetration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Cleavage

A

Zygote to Morula

Chromosomes become arranged on the spindle, split longitudinally and move to opposite poles.

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

What happens once the zygote has reached the 2 cell stage ?

A

It undergoes a series of mitotic divisions, increasing in the number of cells.

These cells, which become smaller with each cleavage division, are known as BLASTOMERES.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How many cells are in the morula ?

A

16-18 cells
takes 72 hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the structure of the morula

A

Inner cell mass - EMBRYOBLAST
which is surrounded by
Outer cell mass - TROPHOBLAST

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What does the embryoblast of the morula give rise to ?

A

Embryo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does the trophoblast of the morula give rise to ?

A

Contributes to the placenta

22
Q

Where do the cavities of the morula form ?

A

Cavities form in inner cell mass, filled with fluid.

23
Q

What does a single blastocyst cavity give rise to ?

A

The single blastocyst cavity will become the primitive yolk sac.

24
Q

Around what day does the blastocyst reach the uterine cavity ?

A

On day 6-7, the blastocyst reaches the uterine cavity.

25
Q

What happens on day 6-7 ?

A

The blastocyst reaches the uterine cavity.

Trophoblast cells over the embryo blast begin to implant into the epithelial cells.

Host/graft and graft/host reactions are normally suppressed.

26
Q

How do the cells in the embryoblast differentiate ?

A

Under the influence of fibroblast growth factors (FGFs) at the early blastocyst stage, cells in the embryoblast differentiate into epiblast and hypoblast cells.

Scattered cells segregate —-> Bilaminar disc

27
Q

What happens on day 8 ?

A

On day 8, the blastocyst is partially embedded in the endometrium of the uterus.

28
Q

What does the trophoblast differentiate into ?

A

In the area over the embryoblast, the trophoblast differentiates into the inner layer of

  • CYTOtrophoblast,

and an outer zone of

  • SYNCYTIOtrophoblast (secretes beta-HCG)
29
Q

What does the syncytiotrophoblast secrete and what is the importance of this ?

A

Secretes - Beta-HCG

This is used to detect pregnancy

30
Q

What and where is the amniotic cavity ?

A

A small cavity appears within the epiblast called amniotic cavity.

31
Q

What happens at day 15 ?

A

Around day 15, Primitive streak appears as a thick structure on the epiblast :

  • In the midline
  • Near the caudal region of the bilaminar embryonic disc
  • Defines the body axes
32
Q

Where is the primitive streak ?

A

IN the midline.
Near the caudal region of the bilaminar embryonic disc

33
Q

What does the primitive streak define ?

A

The body axes

34
Q

Name the parts of the primitive streak

A

Primitive :

  • pit
  • node
  • groove
35
Q

What does the cranial end of the primitive streak contain ?

A

Primitive node which contains the primitive pit

36
Q

What is the groove in the primitive streak called ?

A

Primitive groove

37
Q

What happens at day 16 ?

A

Gastrulation
Bilaminar disc —-> Trilaminar disc

38
Q

Name the 3 layers of the trilaminar disc

A

Ectoderm
Mesoderm
Endoderm

39
Q

What is the ectoderm formed from ?

A

Epiblast

40
Q

What is the endoderm formed from ?

A

Hypoblast

41
Q

Describe invagination

A

Cells of the epiblast migrate through the primitive streak, detach from the epiblast, displace hypoblast and create a third layer.

42
Q

Describe what happens on day 17

A

Cranial and caudal folding

Notochordal plate forms a notochord

43
Q

What is a notochord ?

A

A cylindrical structure which gives instructions to other cells/tissues.

The notochord acts as a temporary axial skeleton for the embryo.

44
Q

What does the paraxial mesoderm give rise to ?

A

Somites
- Sclerotome
- Myotome
- Dermatome

Head mesenchyme

45
Q

What does the lateral plate mesoderm give rise to ?

A

Walls of the body cavities and serous membranes

46
Q

What does the intermediate mesoderm give rise to ?

A

The urogenital system

47
Q

Ectopic pregnancy

A

Implantation of blastocyst in an abnormal location

IN the ovary or anywhere along the path of migration into the uterine cavity.

48
Q

What is the most common ectopic site ?

A

Tubal pregnancies (95%)

49
Q

What do ectopic pregnancies lead to ?

A

Can lead to spontaneous tubal abortion or …

Can lead to maternal mortality if undetected after intraperitoneal rupture of the uterine tube and its vessels.

50
Q

When does the likelihood of tubal rupture and haemorrhage increase ?

A

From the 2nd through the 5th months
Risk of maternal death

Medicine Year 1 Semester 1 - Part 2 (37 decks)

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