HISTOLOGY OF PREGNANCY

Question 1

What is the operational definition of fertile vs. infertile?

Answer 1

Fertile: conception in < 1 year of unprotected sex
Infertile: no conceptions in > 1 year of unprotected sex

Question 2

What is the cumulus-oocyte complex?

Answer 2

Metaphase 2 arrested secondary oocyte, surrounded by granulosa cells (aka cumulus cells); this is what is ovulated from the follicle during the ovulatory phase of the menstrual cycle

Question 3

Describe the path of the cumulus-oocyte complex once its ovulated from the follicle?

Answer 3

Picked up by oviduct fimbria cilia → transported into infundibulum and to lower ampulla (site of fertilization) by ciliary sweeping and smooth muscle peristalsis

Question 4

What else is dependent on ciliary sweeping/peristalsis?

Answer 4

Transport of preimplantation embryo to uterus

Question 5

Ectopic pregnancies comprise of what percentage of total pregnancies in the U.S.? What is a major risk factor and why?

Answer 5

1 – 2%

Cigarette smoking – affects motile cilia function

Question 6

What is continine and what are the effects?

Answer 6

Nicotine metabolite → reduces smooth muscle contractility

Question 7

What is epididymal maturation?

Answer 7

Sperm gain the capacity for motility and interaction with eggs but they remain latent in the epididymis

Question 8

What is capacitation?

Answer 8

Process by which sperm express latent fertility; occurs within the female reproductive tract; completed within Fallopian tube
so the sperm fertility is activated in the female reproductive tract

Question 9

What are the 2 consequences of capacitation?

Answer 9

Novel flagellar motility only seen in Fallopian tube

Express fertility – bind/fuse with eggs

Question 10

Describe the sperm-egg interaction

Answer 10

Small numbers of sperm reach the egg → sperm acrosome reacts → penetrates zona pellucida (egg coat) → fuses with egg

Question 11

What is IVF/describe it

Answer 11

Retrieve oocyte from pre-ovulatory follicle in a natural non-stimulated cycle; sperm fertilize the oocyte in vitro → embryo is then transferred into the uterus

Question 12

What is ICSI (intracytoplasmic sperm injection)?

Answer 12

Single sperm injected directly into oocyte cytoplasm → bypass capacitation, sperm-egg interaction

Question 13

What are the 4 steps of egg response to sperm fusion?

Answer 13

1. Drive egg cortical granule release to block polyspermic fertilization
2. Triggers release of 2nd polar body and completion of meiosis II
3. Initiate mitotic cell cycle
4. Recruit stored maternal mRNA and activate embryonic genome

Question 14

Sperm induce an increase of what mineral and what does this activate?

Answer 14

Calcium → development!

Question 15

How does the fertilized egg coordinate the proper events of activation?

Answer 15

By counting calcium spikes (spike = increase in calcium) – the number of spikes determines the event

Question 16

How does the sperm fusion start the calcium activation? (what do they release)

Answer 16

Phospholipase C – expressed ONLY in sperm; initiates the calcium oscillations

Question 17

What does implantation require?

Answer 17

Hormonally primed endometrium and appropriately aged blastocyst

Question 18

When does the endometrium “implantation window” open and for how long does it remain open?

Answer 18

Opens ~4 – 5 days after post-ovulatory progesterone surge

Remains open 2 – 4 days

Question 19

What is the decidual response?

Answer 19

Set of changes in the endometrium of the uterus that prepare it for implantation of an embryo
- Post-ovulatory remodeling

Question 20

When does the decidual reponse occur and under the influence of what hormone?

Answer 20

Occurs spontaneously during luteal phase of the cycle under the influence of progesterone

Question 21

What are the 3 main reactions that occur during the decidual response?

Answer 21

1. Transformation of stromal cells into secretory decidual cells
2. Influx of immune cells
3. Vascular remodeling

Question 22

What starts the process of implantation?

Answer 22

Initial contact of the trophoblast layer with the columnar epithelium of the wall of the uterus

Question 23

What is the cytotrophoblast?

Answer 23

Inner layer of the trophoblast; cuboidal cells; embryonic cells at the base

Question 24

What is the syncytiotrophoblast?

Answer 24

Outer layer, multinucleated, no cell boundaries, syncytium

This is the leading edge that’s pushing through the wall of the uterus

Question 25

What are the trophoblastic lacunae? What drains into these?

Approximately when do these form?

Answer 25

Spaces in syncytium that increase in size

• Break down of decidual (maternal) blood vessels/maternal blood drains into these
• 9 days after fertilization

Question 26

What forms the primary stem villus?

Answer 26

Syncytial layer followed by some cytotrophoblast that push into the maternal blood space

Question 27

What additional component is in the secondary stem villus?

Answer 27

Fetal mesoderm

Question 28

What is the tertiary stem villus?

Answer 28

Fetal blood vessels now enter the mesoderm core → this system is now where maternal and fetal blood are very close to one another

Question 29

When does uterine vascular remodeling begin? What’s the major event that happens and what does this ensure?

Answer 29

Begins in the first trimester

Trophoblast cells invade decidua and its spiral arteries → ensures adequate delivery of blood to placenta and fetus

Question 30

Characteristics of uterine spiral artery before remodeling

Answer 30

Low flow and high resistance

Remodeling makes it high flow and low resistance (which is more ideal for placenta)

Question 31

What is preeclampsia? Characteristics?

Answer 31

Failure of remodeling during late pregnancy

Poor fetal growth, maternal and fetal mortality, placental ischemia, oxidative stress, elevated syncytial shedding