DSA Fertilization/Implantation Flashcards
Fertilization:
- occurs typically on what day?
- general steps
- binding triggers what in sperm?
- what happenz to ZP?
- prevention of multiple sperms entering?
- male and female pronuclei
- Sperm head passes follicular cells and attaches to the zona pellucida that surrounds the oocyte. sperm ZP3 glycoprotein interaction
- Acrosomal reaction: increase in calcium concentration inside the sperm cell triggers fusion of outer acrosomal membrane with the sperm cell’s plasma membrane and results in exocytosis of most of acrosomal contents
- spermatozoan penetrates ZP
- cell membranes of sperm/oocyte fuse
- Triggers cortical reaction: increase in calcium inside the oocyte, massive exocytosis of cortical granules shortyly sfter sperm/oocyte fusion. prevents polyspermy
- completion of second meiotic division due to increased calcium, results in formation of 2nd polar body (haploid number of unduplicated maternal chromosomes)
- sperm nucleus decondenses and transforms into male pronucleus
- male and female pronuclei fuse, forming the zygote
how does estrogen help sperm transport?
Capacitation:
- where does it occur?
- what is the acrosome reaction
- where does sperm reach the egg, and what barriers must it pass?
Pronucleus formation/first embryonic cleavage
- what happens when sperm enters the egg?
- as this is happening in sperm, what phase is egg completing?
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- what holds unfertilized egg in meiotic arrest at metaphase II?
- what does Ca+2/calmodulin do?
- maternally derived proteins?
- centrosome comes from where and forms what structure that contacts female pronucleus?
- pronuclei membrane status upon fusion?
- chromosomes align on metaphase and what happens?
mingling of chromosomes represents the end of what? beginning of what?
end of fertilization, beginning of embryonic development
- cleavages during first two days
- structure by third day?
- days 4-5 what is cell called now? what are layers?
- what region attaches to the endometrium
- which cells secrete proteases to dissolve the ZP and when?
- what day of development/menstrual cycle does this normally correspond to?
- how does blastocyst cavity form?
- outer cells of blastocyst become the what? and ultimately form what?
- potentency of ICM?
- what does the uterine glandular epithelium synthesize?
- pinopod action?
- when do they appear
- their action enhanced by what, inhibited by what?
Blastocyst secretions:
- what are some compounds it releases to avoid maternal rejection?
- what sustains CL function
hcg closely related to LH, secreted by trophoblast of blastocyst, sustains corpus luteum in presence of rapidly falling levels of maternal LH, hCH is an autocrine factor because it promotes trophoblast growth and placental development
Overview of implantation:
- trophoblasts secrete what?
- trophoblasts differentiate into what two types of cells?
- their characteristics
Cytotrophoblasts: initial role?
syncytiotrophoblasts:
-adhesive, invasive, endocrine functions: describe them
- what is hatching?
- when does it occur
- putative lytic factor is activated by?
Earliest phase of implantation called:
- correct orientation of ICM? how does this occur?
- MUC1 role?
Second stage of implantation:
- how does trophoblast attach to uterine epithelium?
- what causes decidual cells to dislodge?
Final stage of implantation called?
- trophoblast becomes?
- protrustions dissociate endometrial cells by secreting what?
- trophoblasts secrete what autocrine factor? which proteases degrade ecm?
- around site of penetration, uterin stromal cells take on what shape and become rich in what two things?
trophoblast secretes hCG and proteases that promote invasion of endometrial epithelium, metalloproteases and serine proteases degrade the ecm
around site of penetration uterine stromal cells become polyhedral and rich in lipids/glycogen
what is decidualization?
- endometrium becomes?
- decidua regulates what?
- placental accreta?
Development of placenta:
- what are lacunae when do they first appear?
- what are lacunae filled with?
- histotrophic nutrition?
Development of placenta:
- primary chorionic villi?
- secondary chorionic villi?
- tertiary chorionic villi?
oviductal contractions move sperm from sperm reservoir (where) towards?
Cumulus cell matrix is mostly what?
-how do sperm digest it?
hyaluronic acid, they use PH-20 (hyaluronidase)
proposed proteins that help sperm bind to egg
tetraspanin proteins of egg may bind to sperm proteins called izumos
During the cortical reaction alteration of ZP2 to what blocks polyspermy?
normally sperm bind zp3 then zp2, but with cortical reaction they cant bind zp2 and get into the egg
polar body FYI
Timing of pregnancy Embryologist vs Clinician
Twins
-characteristics of these types of twins
A is dyzygotic twin, female ovulates two oocytes, both fertilized, differenrt genetic material
monozygotic, come from same zygote, share genetic material if early division when cells are still totipotent, you can get two individual embryos with their own placentas.
division of inner cell mass w/in blastocele they will share chorion, but have their own amniotic sacs, sacs may fuse.
incomete division of icm, conjoined twins
why does blastocyst really need to be implanted? what is starting to happen?
