Intro to Embryology

Question 1

What is the process called where diploid cells give rise to haploid cells?

Answer 1

Meiosis

Question 2

How many cell divisions happen in meiosis?

Answer 2

Two cell divisions
Meiosis I and Meiosis II

Question 3

Meiosis gives you how many daughter cells?

Answer 3

Four

Question 4

How many chromosomes are in each new daughter cell after meiosis?

Answer 4

23 chromosomes and one sex cell

Question 5

What is the process by which germ cells (or gametes) are produced and mature?

Answer 5

Gametogenesis

Question 6

How many chromosomes do gametes have?

Answer 6

23

Question 7

Female gamete is an

Answer 7

Egg

Question 8

The male gamete is a

Answer 8

Sperm

Question 9

When a female and a male gamete unite, they form a what?

Answer 9

Zygote

Question 10

How many chromosomes in a zygote?

Answer 10

46

Question 11

Oogenesis produces what?

Answer 11

female gametes (ova/egg)

Question 12

In what week of embryonic life do primordial germ cells arrive in the ovary from the yolk sac?

Answer 12

5th week

Question 13

Is proliferation of the oogonia- female stem cells (rapid/slow) during fetal life?

Answer 13

Rapid

Question 14

When does the meiosis of primary oocytes begin?

Answer 14

Before birth- but stops before the first division is complete and remains in the arrested phase until puberty

Question 15

Are primary oocytes vulnerable to damage as they age?

Answer 15

Yes! Syndromes are more likely

Question 16

How many eggs will mature during a woman’s life?

Answer 16

400-500

Question 17

The pituitary gland produces which important hormones in the growth of oocytes and formation of zona pellucida?

Answer 17

Follicle-stimulating hormone FSH and Luteinizing Hormone (LH)

Question 18

The maturation of oocytes takes a primary oocyte and divides it into what two things?

Answer 18

Secondary oocyte and polar body- these then split into one egg and three polar bodies

Question 19

The polar body lies between what two things?

Answer 19

The zona pellucida and the cell membrane of the secondary oocyte.

Question 20

If the oocyte is not fertilized how long before it degenerates?

Answer 20

24 hours

Question 21

What is released from the follicle during ovulation?

Answer 21

Ovum

Question 22

As the follicle ruptures, LH causes the development of what?

Answer 22

Corpus luteum

Question 23

If fertilization occurs, what hormone does the egg begin to produce?

Answer 23

Human chorionic gonadotropin (hCG)

Question 24

The corpus luteum secretes what hormone?

Answer 24

Progesterone

Question 25

How long does the corpus luteum produce progesterone until placental production starts?

Answer 25

up to 4 months

Question 26

What are spermatogonia stem cells?

Answer 26

Immature sperm cells

Question 27

How many days does it take spermatogonia to mature?

Answer 27

74 days

Question 28

Spermatogenesis is regulated by what hormone?

Answer 28

Luteinizing hormone

Question 29

Testosterone binds to what kind of cells to promote spermatogenesis?

Answer 29

Sertoli cells

Question 30

What cells in spermatogenesis are similar to follicular cells in oogenesis?

Answer 30

Sertoli cells

Question 31

What is the transformation of spermatids into spermatozoa called?

Answer 31

Spermiogenesis

Question 32

What covers half of the nuclear surface and contains enzymes to assist in the penetration of the egg?

Answer 32

Acrosome

Question 33

What are the steps of spermiogenesis?

Answer 33

Formation of acrosome
condensation of the nucleus
formation of the neck, middle, and tail
shedding of cytoplasm
all taking approx 64 days

Question 34

Where does fertilization occur?

Answer 34

Fallopian tubes

Question 35

What percentage of sperm deposited in the vagina enters the cervix?

Answer 35

1%

Question 36

Why would the sperm become less mobile?

Answer 36

An egg is not present

Question 37

What is capacitation?

Answer 37

The period of conditioning of the sperm in the female reproductive tract
It lasts about 7 hrs
Removes glycoprotein that overlays the acrosomal region of the spermatozoa

Question 38

What reaction does the zona pellucida induce?

Answer 38

Induces acrosome reaction
mediated by ligand ZP3 zona protein
Release of acrosomal enzymes allows sperm to penetrate the zona

Question 39

After penetration of the zona what does the sperm first come in contact with?

Answer 39

Oocyte surface

Question 40

After fertilization of the egg, what does the cell undergo?

Answer 40

A series of mitotic divisions increase the number of cells called blastomeres, the mass is hardly larger than a zygote

Question 41

Approximately 3 days after fertilization the embryo contains 12-15 cells configured as a solid ball of cells and is called what?

Answer 41

Morula

Question 42

What hormone helps to relax the uterine tube to allow the embryo to complete its journey into the uterus around day 3.5-4

Answer 42

progesterone

Question 43

What is a blastocyst?

Answer 43

A fluid-filled cavity with a collection of cells at one end created by the embryo

Question 44

What is the trophoblast?

Answer 44

Thin outer layer of cells that becomes embryonic part of placenta.

Question 45

What does the inner cell mass give rise to?

Answer 45

embryo and amnion (sack)

Question 46

After 2 days in the uterus the zona pellucida degenerates and disappears to allow what to happen?

Answer 46

Blastocyte hatches to find a permanent home in uterus

Question 47

1st step of the implantation process is called what?

Answer 47

Attachment phase

Question 48

What type of cells have specialized adhesion molecules that bind to the epithelial cells of the endometrium?

Answer 48

Trophoblast cells

Question 49

Trophoblast differentiate into what two layers?

Answer 49

Inner layer - Cytotrophoblast
Outer layer - Syncytiotrophoblast, which extends into the endometrium and derives nourishment from the maternal tissue

Question 50

Why is it thought that one-half of all embryos fail to implant successfully?

Answer 50

They are thought to have severe genetic abnormalities incompatible with survival.