Meiosis, Fertilization, Implantation, Infertility: Detti Flashcards
What are the two key functions of gonads?
- make gametes
2. secrete androgens for spermatogenesis and female uterine preparation
What are the main two hormones influencing female reproduction?
FSH–>follicles–>inhibin
LH –>estradiol
(from GnRH)
What is most important for sperm? T?
FSH=sperm
LH=T
Where are sperm produced?
Seminiferous tubules
What is the journey of sperm production?
STs
Testes tubules
seminiferous tubules
vas deferes
When spermatogonia divide, what happens to progeny?
One goes on to become sperm
Other stays in the pole
What is the progression of sperm names?
Spermato:
- gonia
- cyte
- tids
- zoa
Meiosis produces what from diploid cells?
1 Diploid to 2 haploid cells
What is the size of the egg?
100-120 microns
How far can sperm travel per second?
60 microns (move tail 12-15x per second)
What causes sperm to be unable to move forward?
Inflammation: UID/STD/Fibroid
Causes hyperactivtion: sperm can only burrow, not move forward
How do IUDs work?
Cause reactivation of sperm to stop it from moving forward and eventually destroy it
What are the functional units of the ovary?
Follicles
Where do eggs come from?
Yolk sac (they move to colonize the gonads)
What else comes from yolk sac?
Blood cells
When does yolk sac digress?
about 12 weeks
What does the yolk sac become?
The allantois (stays inside cord)
What do germ cells do in gonads in male? female? when?
Male: dormant til puberty
Female: replicate immediately at 20 weeks
What is the total number of replicated eggs in female fetus?
about 7 million
BOARDS: When is apoptosis of oocytes the highest?
In utero (reduced from 7 million to about 400,000)
What is about the final number of eggs in a female after apoptosis?
about 400,000
What is the number of eggs on average at birth?
1-2 million, reduces to 400,000 up to puberty
What is the normal time from puberty to menopause?
about 40 years
BOATRDS: For each egg ovulated, how many undergo apoptosis?
about 1000
How many eggs remain at menopause? What happens to them after?
about 1000
apoptosis
What part of the ovary contains the oocytes?
cortex
How many eggs in a follicle?
always 1 to 1
What is the progression of follicles?
Primordial
Primary-cubic flat granulosa starts to change
Secondary-egg grows larger, multiple layers of granules, fluid starts growing, estrogen begins secretion
Tertiary: fluid makes this one larger than others, aka graffian follicle
TEST: What causes formation of the zone pellucida?
Glycoprotein accumulation in cytoplasm of egg
TEST: What stage are eggs stalled in until follicular development?
Prophase I of Meiosis I
What causes differences between siblings?
Crossing over: shuffling of genes
When does crossing over occur?
Prophase I
When we see a nucleus, what do we know about the egg’s stage?
Immature oocyte, diploid
What happens after ovulation to polar body?
Egg extrudes polar body after Meiosis I is complete, sometimes polar body divides after being extrusions
What is notable about the polar body? Haploid or diploid?
Diploid=polar body
When is meiosis II completed in egg?
Only if sperm penetration occurs
How many polar bodies eventually get formed in female?
3 polar bodies
1 egg
What type of oocyte is ovulated?
Secondary oocyte
What stage is egg in if there is still a polar body?
Meiosis II (extrusion occurs after sperm penetrates)
When does meiosis II finish?
After fertilization
How do we tell if egg has been fertilized?
Two nuclei at 12-14 hours, polar bodies gone and egg nuclei has formed again.
When is a zygote formed?
When egg and sperm nuclei fuse, 2 cells stage.
When is zygote in 2 cell stage? 4 cells? 8 cells?
1 day
2 day
3 day
When does zygote become morula?
after 8 cell stage–>16 cells
When is blastocyst stage?
Day 5 or 6
What is the most common site of fertilization and ectopic pregnancy?
Ampulla of tube
After implantation of the blastocyst, what becomes the embryo?
Inner cell mass
After implantation of the blastocyst, what becomes the placenta?
Outer cell mass
What part of the implanted blastocyst produces hCG?
Outer cell mass (becomes placenta)
What does hCG function as in the body?
LH–>makes granulosa cells make progesterone via hCG on LH receptor
BOARDS: What allows uterus to grow the emplaned embryo?
hCG secretions from placenta causing progesterone release from corpus luteum
BOARDS: If you see a small sac on uterine wall, what makes it more likely to be a implanted pregnancy rather than a cyst of blood from an ectopic pregnancy failure?
Implant: on wall
Cyst: in center more likely if blood cyst
What is gestational age calculated from?
Date of last menstual period
When does normal embryonic life begin?
About 2 weeks after the last menstrual period: age of pregnancy is last period + 2 weeks
3 weeks of embryonic life=how many weeks of gestation?
5 weeks gestation=3 weeks embryonic life
What is the image of 3 weeks embryo/5 weeks gestation?
Signet ring sign (yolk sac makes a ring with trophoblast on top)
8 week embryo is how many weeks gestation?
8 week embryo = 10 weeks gestation
How do you calculate embryo age?
Subtract 2 weeks from gestational age
At what point can you see the head, arms, legs, cord?
8wks embryo/10 wks gestational
TEST? At what stage is the yolk sac transformed fully into the alantois?
12 wks
What is the percentage likelihood of getting pregnant between a normal couple trying per cycle? mice?
20-25% (we are inefficient species)
100%… mice don’t live long
What percentage of normal fertile couples can get pregnant within 3 months? 6? 1 yr? 2yrs?
3 mo: 57%
6 mo: 72%
1 yr: 85%
2 yr: 93%
If we have a couple who have tried for 1 year and are not pregnant, what can we say?
Sub fertile couple
What percent of people are sub fertile?
10-15% of people (cannot get pregnant within 1 year of trying)
How many eggs does a woman have at birth? puberty? 37-38 yrs? Menopause?
birth: 1-2 million
puberty: 300-500k
37-38: 25,000
meno: 1,000
What is the age cut off for infertility specialists?
under 35: >1 year, see someone
over 35: >6 months, see someone
How many minutes does it take for a sperm to get to the egg to fertilize?
about 5 min… woah!
What has to happen for fertilization?
- sperm must swim
- cervix must allow
- ovulation of M2 oocyte must occur
- tubes must capture oocyte and sperm
- uterus must receive`
What percent of infertility is male? Female? Combined?
Male: 40%
Female: 60%
Combo: 20%
Of female error, how does it break down between cervical? uterine? tubes? peritoneal? ovulation?
Cervix: 5-10% Uterus: 5-10% Tubes : 30-40% Peritoneal: 30-40% Ovulatory: 10%
What is the most common error in female?
Tubes
peritoneum
(endometriosis, PID)
What is the most common ovulatory error?
PCOS: Polycystic ovarian syndrome
If a man goes to the gym and takes steroids, what happens?
Infertility!
What are the analytics for semen?
Volume: 1.5-5ml Concen: >20 million/ml Motility: >40% Morpho:>14% pH: >7.2 (alkali?) Round cells: <1 mil/ml
What do round cells mean in sperm?
Inflammation or infection (come from prostate)
What do round cells do to sperm?
Premature activation: just burrow, don’t swim
What do you do if you see round cells in semen?
antibiotics for 1 month
What is the cause of retrograde ejactulation in males?
Type I diabetes… woah
What are other investigations for male fertility other than semen?
Retrograde ejaculation Duct obstruction Hypogonadism CBAVD Endocrine: FSH, LH, PRL, T Karyotype Y Chromosomal microdeletions
What is the main problem in uterine infertility?
Fibroids> adhesions> congenital
Endometriosis> decreased receptivity
What is the main ovarian error?
oligo/anovulaion
luteal phase deficiency
polycystic ovarian disease
What is the definition of a polycystic ovary?
> 12 follicle cysts per ovary
