Embryology, Conception, & Fetal Development

Question 1

Phases of the endometrial cycle

Answer 1

• menstrual phase (days 1-5/7)
• proliferative phase (day 5 to ovulation/15))
• secretory phase (days 15-28)
• ischemic phase (days 28-30ish)

Question 2

Phases of the ovarian cycle

Answer 2

• follicular phase (days 1-14)
• ovulation (day 15/18)
• luteal phase (days 15-28)

Question 3

graafian follicle

Answer 3

fluid-filled structure where the ovum develops into a mature oocyte that ruptures to release the ovum during ovulation

Question 4

what does the heightened estrogen and progesterone levels during the secretory phase do to the uterine lining?

Answer 4

it prepares the uterine lining for implantation

Question 5

When does ovulation occur in relation to menses?

Answer 5

14 days prior to menstruation

Question 6

When is a woman most fertile?

Answer 6

during ovulation

Question 7

How many days does the sperm last?

Answer 7

3-5 days

Question 8

How many days does an ovum survive?

Answer 8

12-24 hours

Question 9

What is cervical mucus like when not ovulating?

Answer 9

dry or sticky

Question 10

What is cervical mucus like when ovulating/fertile?

Answer 10

wet and sticky- resembles raw egg whites

Question 11

When is sex determined?

Answer 11

At fertilization as the chromosomes combine to be XX or XY

Not known until 18-21 weeks

Question 12

Oogenesis

Answer 12

• primordial germinal cells divide repeatedly to form the oogonia
• oogonia go through mitotic division to form the primary oocyte
• in the growth phase the size of the primary oocyte increases enormously and then goes through two phases of meiosis to form a haploid egg cell

Question 13

Spermatogenesis

Answer 13

• spermatogonia
• primary spermatocytes
• secondary spermatocytes
• spermatids
• spermatozoa

Question 14

Mitosis and meiosis differences

Answer 14

mitosis

• maintenance of chromosome number (diploid)
• takes place in somatic cells
• no crossing over

meiosis

• reduction of chromosome number (haploid)
• takes place in reproductive cells
• crossing over occurs

Question 15

Stages of prenatal development

Answer 15

• germinal stage= the two weeks from formation of the zygote to implantation
• embryonic period= the third through eighth week where the embryo forms its basic organs, CNS, and PNS
• fetal period= ninth week through birth

Question 16

Morula

Answer 16

a mass of 16 blastomeres formed by cleavage of the zygote that forms before a blastocyst on day 4

Question 17

Blastocyst

Answer 17

32+ rapidly dividing cells whos inner group will become the emrbyo and outer group will become to amnion

Question 18

When does implantation occur?

Answer 18

6-12 days after ovulation when the blastocyst implants after shedding the zona pellucida

Question 19

Ectoderm

Answer 19

outer germ cell layer that forms the skin, hair, nails, glands, and PNS

Question 20

Mesoderm

Answer 20

middle germ cell layer that becomes the dermis, heart, muscles, urinary system, etc

Question 21

Endoderm

Answer 21

inner germ cell later that becomes the inner lining and other organs

Question 22

What are the purposes of the placenta?

Answer 22

• serves as fetal lungs, liver, and kidney until birth

- upkeeps healthy growth environment (immune attack, remove waste products, etc)

Question 23

What hormones does the placenta produce?

Answer 23

• human chorionic gonadotropin hormone= tells the uterus to stop shedding its lining and thickens it for the growing embryos
• human lactogen= provides nutrition to the fetus and stimulates the mother’s milk glands
• estrogen
• progesterone

Question 24

Ductus arteriosus

Answer 24

connects the aorta to the pulmonary artery which shunts blood away from the lungs

Question 25

Foramen ovale

Answer 25

allows oxygenated blood into the right atrium so it can enter the left atrium to bypass going through the lungs for gas exchnage

Question 26

Ductus venosus

Answer 26

connects the umbillical vein to the vena cava shunting the deoxygenated blood away from the liver

Question 27

Why are the 3 structures of the fetal heart not in the newborn heart?

Answer 27

Because the fetus does not have working lungs or a liver

Question 28

How many cord vessels and which carries oxygenated blood to and from where?

Answer 28

• 1 umbillical vein carries oxygenated blood from the placenta
• 2 umbillical arteries carry deoxygeated blood to the placenta

Question 29

Wharton’s jelly

Answer 29

surrounds the vessels to prevent compression of the umbillical cord

Question 30

When does FSH peak?

Answer 30

the 1st week of the menstrual cycle

Question 31

When does gonadotropin-releasing hormone peak?

Answer 31

at the beginning of the ovarian cycle

Question 32

When does luteinizing hormone peak?

Answer 32

12-24 hrs before follicle rupture/ovulation

Question 33

When is estrogen at its peak?

Answer 33

right before ovulation

Question 34

When is progesterone at its peak?

Answer 34

5-7 days after ovulation