Development II- Lecture 9/21/21 Flashcards
Corpus luteum secretion
Secretes progesterone until 20 weeks of gestation
hGH
Human chorionic gonadotropin, secreted from the implanted blastocyst, tells corpus luteum to keep secreting progesterone
Sperm transport
Swim faster in alkaline environments, varying with pH, moves along by uterine contractions stimulated by PGE2 in semen
Minimum sperm level for fertility
About 10 million/mL
Normal sperm concentration
100 million/mL of ejaculate, usually about 2-6 mL
Sperm capacitation
Takes 6-8 hrs, glycoproteins coat removed from acrosome surface and can swim and fertilize
Acrosome rxn
Initiated when bing to ZP3, causes membrane to perforate, releasing enzymes that can break down the matrix
The eureka moment (fusion)
Plasma membranes of the oocyte and sperm fuse, official start of fertilization (takes 24 hours), egg completes meiosis II
Cortical reaction
Blocks polyspermy, membrane fusion triggers rapid and massive exocytosis of the cortical granule contents, destroys ZP3 and cross links matrix proteins
ZP3
Zona pellucida protein 3, protein recognized by sperm, species specific
Cortical granule
Contains enzymes for cross linkages, rests just below plasma membrane, derived from the lysosome
Calcium wave
happens when oocyte is penetrated, stimulates meiosis II
Nucleus fusion
Oocyte chromosomes decondense and form a pro nucleus, new sperm nucleus forms pro nucleus, nuclei fuse and all chromosomes replicate, end of fertilization
Results of fertilization (3)
- Stimulates the secondary oocyte to complete meiosis II
- Restores diploid number
- Determines the sex
Polyspermy
Can cause a trip load zygote, account for 20% of spontaneous abortion, only a few survive to birth, only last a couple days
Blastomeres
Early cells after replication, all identical and all replicate together, no bigger because of zona pellucida
Trophoblast
Cells that will go on to form the placenta (about day 3-4)
Inner cell mass
Embryonic stem cells that will form the fetus
Hatching
The shedding of the zona pellucida at day 4-5 which permits the embryo to implant
Gastrualtion
The three germ layers form
Late blastocyst
Forms at day 12-14, about a week after beginning implantation
Implantation completion
At about the end of 2 weeks after fertilization, bilaminar embryonic disc forms
Pre-implantation genetic diagnosis
Blastomeres can be removed for PGD, not, take some of the trophoblasts from blastocysts
Timing of formation of blastocyst
4-5 days post fertilization
Blastocoel cavity
Where the cells of the blastocyst secrete their fluid to facilitate hatching
Inner cell mass
Dense part of the blastocyst, will become the embryo
Trophoblast
Outer part, will become the placenta
When the blastocyst attaches to the endometrium
About day 6
Bilaminar disc
The embryo develops the bilaminar disk at about 8-12 days
Epiblast
1/2 of the bilaminar disc, will become the three germ layers
Completion of implantation timing
12-14 days
Endometrial storma cells
Produce PGE2 which blocks the activation of T-cells and NK cells, producing immunologic immunity
Gastrulatuon timing
14-15 days
Gasstrulation
The epiblast becomes all three layers, hypoblast delaminates to get out of the way
Spontaneous abortion
When the embryo is grossly abnormal, the body just rejects it
Spontaneous abortion rate
About 50%
Major causes of spontaneous abortion (3)
Chromosomal abnormalities
Cleavage problems
Progesterone insufficiency
Infertility definition
A year of unprotected intercourse at the right time without achieving pregnancy
Causes of infertility
~30% male, 30 female 10 both and 25 unexplained
Oligomenorrhea
Lack of menstrual period for 3 months
Amenorrhea
Complete absence of menstrual periods
Causes of ovulation defects (3)
Hypothalamic abnormalities (GnRH)
Reduced secretion of FSH and LH
-Extreme athletic activity, stress, eating disorders
Polycystic ovary syndrome
Irregular ovulation or an ovulation, increased LH levels as compared to FSH levels, most common hormonal disturbance
Anatomical abnormalities of the reproductive tract (4)
- Endometriosis
- Chronic PID
- Tubal obstructions
- Uterine abnormalities, usually fibroids
Mayer-Rokitansky-Kusher-Hauser syndrome
Congenital uterine development anomalies, complete absence of a uterus
Asherman’s syndrome
Excessive scar tissue in the uterus, can be caused after uterine surgeries, D and c, myomectomy etc
Excessive scar tissue from STIs
Scar tissue in the vaginal canal/cervix, different from Asherman’s (cannot be treated surgically
Azoospermia
No sperm cells
Oligospermia
Few sperm cells
Causes of low sperm number (6)
-Testicular defects Hormonal abnormalities Varicocele Damage to vas deferents Ejaculation disorders Defects in capacitation
Maternal aging
Over 35 is at risk, after 40 over hal of gametes at aneuploid
Treatment for PCOS
Subcutaneous FSH injection
Immotile sperm treatment
IVF using ICSI
Multiple miscarriages treatment
Progesterone treatment
Lack of GnRH production treatment
GnRH therapy
Menopause options
Adoption and donor egg IVF only options
Fertility unexplained algorithm (<35)
Start with clomiphene treatment with IUI, and go one to try more complex treatments
Fertility unexplained algorithm (>35)
Straight to IVF
IUI
Intrauterine insemination
Clomiphene Citrate
Orally administered hypothalamus estrogen receptor blockage, stimulates pituitary to keep secreting LH and FSH, used to regulate ovulation or induce ovulation
HMG
Human menopausal gonadotrophins, given by daily injection, have to monitor by US when to administer, mimics LH surge
HCG
Human chorionic ganadotropin, mimics LH surge, used to trigger multiple ovulation
ICSI
Intracytoplasmic sperm injection
