Gametogenesis, Fertilization, Implantation - Kuehl

Question 1

Through what do stem cell populations for gametes expand?

Answer 1

Through mitosis

Question 2

Through what processes do gametes in each gender reduce their chromosomes to half the normal number for an individual? And how many chromosomes?

Answer 2

1) meiosis

2) 46 –> 23

Question 3

In what process are alleles of genes rearranged to make new unique combos?

Answer 3

Meiosis

Question 4

When are errors not repaired in gametes?

Answer 4

errors related to pre-meiotic cell divisions for germ cell numeric expansion and during meiosis are not repaired

Question 5

When can nondysjunction occur and what is it?

Answer 5

1) can occur in both mitosis and meiosis

2) failure of chromosomes to separate

Question 6

When do errors such as inversions, deletions or duplications occur?

Answer 6

Meiosis

Question 7

What is the difference between DAZy and DAZL?

Answer 7

1) DAZy = present in higher primates

2) DAZL = located on chromosome 3 (autosomal) and expressed in both testes and fetal ovaries

Question 8

What is Y chromosome microdeletion and what are its symptoms?

Answer 8

An inherited disorder of gene deletions on the Y chromosome that often goes unnoticed until infertility becomes obvious (reduced sperm production)

Question 9

What is the proposed mechanism for DAZ function?

Answer 9

1) Gamete production - augments mRNA translation to proteins
2) DAZL and DAZy bind to mRNA and poly-A binding proteins to circularize mRNA and enhance translation

Question 10

What happens in a male with a DAZy deleted phenotype?

Answer 10

1) few or no sperm cells in the ejaculate - but some limited spermatogenesis in testes
2) fathers are genotypically normal
3) DAZy deleted males can still reproduce bc of ART - will always have DAZy deleted sons

Question 11

What has helped the understanding of aneuploidy transmission?

Answer 11

1) ART (assisted reproductive technology)

2) polar body biopsy

Question 12

What percent of women bw the ages of 19-29 donating ova had errors of mitosis, meiosis or both?

Answer 12

32%

Question 13

Do ova with abnormal chromosome numbers have decreased fertilization?

Answer 13

NO

Question 14

What kinds of errors increase with age?

Answer 14

errors due to meiosis

Question 15

What is seen as a consequence of age with pregnancy?

Answer 15

1) increased chormosomal numerical errors leading to
a) lethal defects - stillbirth/abortions
b) nonlethal defects - down syndrome

Question 16

Where is mitosis in the female for the germline finished?

Answer 16

in the fetus

Question 17

Where is meiosis started and finished in the female?

Answer 17

1) initiated in the fetus
2) arrested at prophase I of meiosis prior to recombination
3) restarted by LH signal that triggers ovulations
4) completed after fertilization

Question 18

When does mitosis begin in the male?

Answer 18

begins in the fetus and continues throughout life

Question 19

When does meiosis begin in the male?

Answer 19

begins at puberty

Question 20

What are the differences in stem cell populations of germ cells in the male and female?

Answer 20

1) males maintain stem cell populations of germ cells into adulthood
2) females lose stem cell populations as meiosis of all oogonia initiates in utero

Question 21

Why do male germ cells entering into spermatogenesis maintain cell-to-cell connections?

Answer 21

so the development is the same for X and Y containing cells

Question 22

What do haploid sperm cells express at puberty?

Answer 22

antigens - well after immune function is established

Question 23

What hormones do follicular cells produce?

Answer 23

1) estradiol
2) progesterone
3) inhibins

Question 24

What do nongrowing (NGF) or primordial follicles represent?

Answer 24

the population of follicles with potential for future reproduction

Question 25

What limits the duration of reproduction in females?

Answer 25

1) lack of oocyte stem cells
2) NGF lost to atresia or growth
3) drop below 1,000 NGF

Question 26

What can increase the reduction of NGF in women?

Answer 26

1) chemotherapy

2) smoking

Question 27

What can you use as a reference point to estimate reproductive age?

Answer 27

ovarian volume

Question 28

How long does it take a primordial follicle to move through all the stages of development to an ovulatory follicle?

Answer 28

4 months

Question 29

What is the time keeper of the cycle of primordial development?

Answer 29

the ovary

Question 30

What do sertoli cells do?

Answer 30

1) provide an environment for spermatogenesis

2) provide ABP to carry androgen to the rest of tubule system

Question 31

Why are testes more prone to edema disruption?

Answer 31

lymph collection at the septa instead of interstitial spaces?

Question 32

What kinds of processes can alter spermatogenesis?

Answer 32

1) processes impacting perfusion
a) heavy metal toxicity
b) diabetes, atherosclerosis
c) increased venous pressure
d) thick basement membranes
e) altered hormone delivery

Question 33

What maintains the blood testes barrier?

Answer 33

tight junctions between sertoli cells

Question 34

Is there any differences between X and Y carrying sperm?

Answer 34

Nope

Question 35

What increases with age in sperm?

Answer 35

mutations

Question 36

What kind of errors in sperm are not transmitted and what kind are?

Answer 36

1) errors in alleles that directly impact sperm function lead to sperm being apoptotic
2) errors in genes not expressed in sperm cells can be transmitted

Question 37

What primarily determines the selection of sperm for fertilization?

Answer 37

barriers within the female reproductive tract

Question 38

What is the risk for chromosome abnormalities with age in women?

Answer 38

1) 50% in women < 35
2) 75% 35-40
3) 90% > 40

Question 39

What are possible male contributions to errors in the embryo?

Answer 39

1) sex chromosome number abnormalities
2) autosomal translocations
3) genetic mutations and size of repeats

Question 40

How is the oocyte in the fastest growing follicle maintained?

Answer 40

negative hormonal feedback mechanisms

Question 41

Probes for which chromosomes are used in FISH during ART?

Answer 41

11, 13, 16, 18, 21, X and Y

Question 42

By what days has the embryo turned of gene expression?

Answer 42

hCG beta - 8 cell stage

Question 43

How often does hCG double in a normal early pregnancy?

Answer 43

Every TWO days!