Gametogenesis, Fertilization, Implantation - Kuehl Flashcards
(43 cards)
Through what do stem cell populations for gametes expand?
Through mitosis
Through what processes do gametes in each gender reduce their chromosomes to half the normal number for an individual? And how many chromosomes?
1) meiosis
2) 46 –> 23
In what process are alleles of genes rearranged to make new unique combos?
Meiosis
When are errors not repaired in gametes?
errors related to pre-meiotic cell divisions for germ cell numeric expansion and during meiosis are not repaired
When can nondysjunction occur and what is it?
1) can occur in both mitosis and meiosis
2) failure of chromosomes to separate
When do errors such as inversions, deletions or duplications occur?
Meiosis
What is the difference between DAZy and DAZL?
1) DAZy = present in higher primates
2) DAZL = located on chromosome 3 (autosomal) and expressed in both testes and fetal ovaries
What is Y chromosome microdeletion and what are its symptoms?
An inherited disorder of gene deletions on the Y chromosome that often goes unnoticed until infertility becomes obvious (reduced sperm production)
What is the proposed mechanism for DAZ function?
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
What happens in a male with a DAZy deleted phenotype?
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
What has helped the understanding of aneuploidy transmission?
1) ART (assisted reproductive technology)
2) polar body biopsy
What percent of women bw the ages of 19-29 donating ova had errors of mitosis, meiosis or both?
32%
Do ova with abnormal chromosome numbers have decreased fertilization?
NO
What kinds of errors increase with age?
errors due to meiosis
What is seen as a consequence of age with pregnancy?
1) increased chormosomal numerical errors leading to
a) lethal defects - stillbirth/abortions
b) nonlethal defects - down syndrome
Where is mitosis in the female for the germline finished?
in the fetus
Where is meiosis started and finished in the female?
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
When does mitosis begin in the male?
begins in the fetus and continues throughout life
When does meiosis begin in the male?
begins at puberty
What are the differences in stem cell populations of germ cells in the male and female?
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
Why do male germ cells entering into spermatogenesis maintain cell-to-cell connections?
so the development is the same for X and Y containing cells
What do haploid sperm cells express at puberty?
antigens - well after immune function is established
What hormones do follicular cells produce?
1) estradiol
2) progesterone
3) inhibins
What do nongrowing (NGF) or primordial follicles represent?
the population of follicles with potential for future reproduction
