Embryo Flashcards
Where frrtilization occur and What are 1st 2 of the 3 phases of fertilization
At ampulla
Phase1- entrance:200-500m sperm are released hundreds go to fallopian tube and capacitation occur
Phase2-attachment and penetration throgh zona pellucida: sperm glycosyltansferase attach to ZP3 receptor of ZP. And acrosomal reaction(fusion of sperm outer n inner membranes & release of enzymes(hyaluronidases and acrosin*)start
Sperm head touches secondary oocyte in metaphase of m-II and cortical reaction occurs(release of lysosomal enzymes block zp3 nd polyspermy block occurs 2nd meiotic division completes)
3rd phase of fertilization
What occurs next
What the part of cell that comes only from mother which one from father only
Phase 3-Fusion of nuclei: sperm nucleus and pair of centrioles enter secondary oocyte hence all mitochondria are maternal and because oocyte loses its centrioles during mitosis therefore only source remains is sperm centrioles of making microtubule organizing center MTOC
Then secondary oocyte completes its second meiotic division and female pronucleus form
Syngamy occurs
Zygote is formed yohoo!
How can we measure age of conceptus
The age of a developing conceptus can be measured either from the estimated day of fertilization (fertilization age) or from the day of the last normal menstrual period
What are phases of mentrual cycle and their other names and major hormones during each of them
When ovulation occur
2 phases
1-pre-ovulatory phase- also called follicular phase(proliferative and menstrual phase)
Major hormone are FSH LH and estrogen
2- post ovulatory phase- also called luteal phase( secretory phase)
major hormone is progesterone
14th day
What occurs during pre-ovulatory phase
Growing follicle consist of thica cells and granulosa cells
Thica cells bear receptors for LH and release androgen which is converted to estrogen with the help of granulose cells.
Granulosa cells bear receptors for FSH and convert androgen into estrogen
i) growing follicle estrogen acts as -ve feedback and ! Fsh
ii) dominant follicle estrogen act as +ve feedback and î fsh and Î LH and thus ovulation occur
Function of estrogen
i) thicken endometrium
ii) grow endometrial glands
iii) make spiral arteries
iv) increase consistency (less thicken) of cervical mucus which is sign for ovulation
What occurs in Post ovulatory phase(luteal phase)
After ovulation remnant of follicle becomes corpus luteum which release progesterone —> thicken cervical mucus and decrease FSH and LH and thus estrogen level decrease as well make endometrium secretory
With time corpus luteum is converted to corpus albicans which does not release any hormone at all and hence i) spiral arteries collapse
ii) functional layer sloughs off -> menstruation
Different stages of conceptus with their days upto 3rd day
Which cells are totipotent
Which are pleuripotent
Fertilazation,zygote—> 1st day-at ampula……….2nd and 4th celled stage—> 2nd day-at fallopian tube with zp……..8 and, 16-celled-stage(morula), (each cell is called blastomere)-at fallopian tube……… division occurs+ fluid is secreted within morula-> blastocyst cavity formed and inner cell mass is called embryoblast The outer cell mass of the blastocyst is called the trophoblast—>3rd day-at fallopian tube
Blastomeres are totipotent while embryoblast cells are pleuripotent
implantation occur 1)where 2)which layer 3) when 4) which phase
Posterior wall of uterus
Functional layer of endometrium
At the start of 4th day blastocyst is transferred to uterus……implant by day 7
In secretory phase(progesteronal phase)
After implantation Trophoblast blast cells convert into ____ and what’s the difference between them.
Why failure of implantation may occur
The trophoblast proliferates and differentiates into the cytotrophoblast(monunucleatid and do mitosis) and syncytiotrophoblast(multinucleated and mitosis does not occur and they come from cytotrophoblast cells)
Failure of implantation may involve immune rejection (graft-versus-host reaction) of the antigenic conceptus by the mother.
What is etp and its cause and site**
ETP occurs when the blastocyst implants within the uterine tube due to delayed transport.
- The ampulla of the uterine tube is the most common site of an ectopic pregnancy. The rectouterine pouch (pouch of Douglas) is a common site for an ectopic abdominal pregnancy
which women are more vulnerable to etp. Etp leads to ___ .. symptoms
ETP is most commonly seen in women with endometriosis or pelvic inflammatory disease.
4. ETP leads to uterine tube rupture and hemorrhage if surgical intervention (i.e., salpingectomy) is not performed.
- ETP presents with abnormal uterine bleeding, unilateral pelvic pain, increased levels of human chorionic gonadotropin (hCG) (but lower than originally expected with uterine implantation pregnancy), and a massive first-trimester bleed.
Which are similar problems like etp
appendicitis, an aborting intrauterine pregnancy, or a bleeding corpus luteum of a normal intrauterine pregnancy.
By which day zona pellucida degenerate
Zona pellucida degeneration occurs by day 4 after conception. The zona pellucida must degenerate for implantation to occur.
What happens by day 7 or 8, 9,11,12,14
By day 7 or 8—>blastocyst implants to decidua……..by day 9–>synciotrophoblast is pushed deeper to decidua bacillus……….bt day 11–>completely burried into decidua……..by day 12—>decidual reaction occurs+epithelium regenerated+EEM begins to form,………,,day 14–>syncytiotrophoblast cells protrude out called primary villi
During 2nd week what happens to embryoblast cells .
tell all differences between layers
They form bilaminar embryonic disc.
Hypoblast:-1)ventral 2)cuboid cells 3)form yolk sac(initially primitive which is then converted to definitive yolk sac) 4) at the future site of the mouth, hypoblast cells become columnar shaped and fuse with epiblast cells to form a circular, midline thickening called the prochordal plate.
Epiblast:- 1)dorsal 2)columnar cells 3)forms amniotic cavity 4)becomes germ layers later
Extraembryonic mesoderm (EEM) is formed by what and when does it form
Extraembryonic mesoderm (EEM) is form by cells of epiblast between cytotrophoblast and bilaminar embryonic disc
What is decidual reaction, when it occurs
High progesterone—>decidual cells enlarged and coated in sugar rich fatty acids
Occurs at day 12
What’s extraembryonic mesoderm ,from where it develops and what it generates
EEM is formed by epiblast between exocoelomic membrane and cytotrophoblast,,large spaces are generated which combine to form extraembryonic coelom which differentiate EEM into extraembryonic somatic mesoderm and extraembryonic visceral mesoderm
what are EESM and EEVM.what chorion and chorionic cavity
What the relation here between conceptus and chorion
EESM covers cytotrophoblast and forms connecting stalk and cover amnion, EEVM covers yolk sac… chorion is seen here it consists of EESM+cytotrophoblast+synctiotrophoblast .EEC is then called chorionic cavity. Conceptus is suspended in chorionic cavity by connecting stalk
What is HcG ,when and from where it is produced, it stimulates the production of______ which does the _______ function
Human chorionic gonadotropin is a glycoprotein produced by syncytiotrophoblast at day 8 and it stimulates production of progesterone which is important for maintenance of pregnancy until week 8. The placenta then takes over progesterone production
How and when we can detect pregnancy.
What different values suggest
We can detect pregnancy at day 8 from blood or day 10 from urine by watching hcG . Low level suggest an ectopic pregnancy or spontaneous abortion while high level suggest multiple pregnancy ,hydatidiform mole, or gestational trophoblastic neoplasia.
Medication to stop pregnancy untill ___
RU-486 (mifepristone; Mifeprex) initiates m tion when taken within 8–10 weeks of the start of the last menstrual period. If implantation of a conceptus has occurred, the conceptus will be sloughed along with the endometrium. RU-486 is a progesterone-receptor antagonist (blocker) used in conjunction with misoprostol (Cytotec; a prostaglandin E1 [PgE1 ] analogue) and is 96% effective at terminating pregnancy.
What forms in gastrulation by day
Cells are ______potent
Gastrulation is the process that establishes the three definitive germ layers of the embryo (ectoderm, intraembryonic mesoderm, and endoderm), forming a trilaminar embryonic disk by day 21 of development. Cells are totipotent
