FOM 6.1.3 Flashcards
What is the first step in female ovulation?
Follicle rupture and release of oocyte and corona radiata cells that are swept in to ampulla
What are the two steps spermatozoa must undergo?
capacitation and acrosome reaction
Where is the most likely spot of fertilization?
Ampulla of the uterine tube
What is the process of sperm capacitation?
Sperm passing through the uterine tube causes changes. These are removal of glycoprotein coat and seminal plasma proteins from plasma membrane. This leads to exposure of receptors on sperm acrosome cap
What is the acrosome reaction?
Leads to release of enzymes that is needed to penetrate the zona pellucida. Sperm binding is mediated by ZP3 the ligand for the sperm receptor. After penetrating zona pellucida it contacts the plasma membrane of oocyte
What are the three phases of fertilization?
What happens after fertilization and what is it meant to prevent?
Sperm head contactin the oocyte surface leads to release of lysosomal enzymes from cortical granules lining oocyte plasma membrane (Cortical Reaction). Oocyte membrane becomes inpenetrable to other sperm. Then the zona pellucida properties are altered to prevent further binding and penetration.
What is the importance of compaction of the blastomere?
Cell to cell contacts are maximized
Segragation of inner and outer cells and the inner cells communicate via gap junctions
What are the components of the morula?
Inner cell mass which is the embryo proper, amnion, and yolk sac
Outer cell mass which is the trophoblast which will later contribute to fetal portion of the placenta
What are the componenta os the blastocyst and what is the main event that yields the blastocyst?
Trophoblast cells or outer cell mass and the inner cell mass or embryoblast
Fluid penetration into intercellular spaces of ICM results in blastocele cavity
What are the two red arrows pointing to?
Top : Outer cell mass or trophoblast
Bottom : Inner cell mass or embryoblast
What is known as the hatching event in development of blastocyst?
Trophoblast cells at the embryonic pole of the blastocyst bind and penetrate uterine endometrium
What is the important hormone associated with maintaining of the endometrium
Progesterone
Implantation of the blastocyst leads to development of what?
Large corpus luteum of pregnancy.
The trophoblast comprised of what?
The cytotrophoblast (inner lay with mononuclear cells) and the syncytiotrophoblast (outer later without distinct cell boundaries).
The embryoblast is formed by what?
The epiblast and hypoblast
What is important about the syncytiotrophoblast?
It secretes human chorionic gonadotropin
What are the results of a pregnancy that is outside the uterus?
There are many fates that can happen. One is a tubal pregnancy that can be very dangerous for the mother. It can lead to a rupture in the ampulla and bleeding. There is also an abdominal pregnancy that can actually be viable to term if placenta can be removed without causing hemorrhaging.
After the oocyte has left the ovary what continues to release progesterone?
The corpus luteum secretes progesterone to prepare the uterine wall for implantation
What is the basic process of implantation from beginning?
This is far from basic mwahahahahahhaa!!!!!
Mature follicle in the ovary ruptures and releases oocyte surrounded by cumulus cells. The oocyte then travels to the ampulla. The corpus luteum then stays in the ovary to secrete progesterone. The sperm must travel down the ampulla and get to through the corona radiata and zona pellucida before entering. Once entering, the zona becomes specialized. Formation of 2 pronuclei, and intermingling leads to cell division. Formation of morula then blastocyst. Syncytioblast lacks boundaries and secretes enzyme that allows for implantation. The cytotrophoblast has boundaries.
Where do trophoblast cells come from?
The outer cell mass.
What will the trophoblast later contribute to?
The fetal portion of the placenta
What is the embryoblast derived from?
The inner cell mass
Where does the primitive yolk sac come from?
The exoceolomic cavity
Where does the secondary yolk sace come from?
Secondary yolk sac forms within the exocoelomic cavity.
What is an ectopic pregnancy?
A pregnancy that occurs outside the uterus and the embryo tends to die at second month
Sperm present in the uterus or uterine tube during ovulation swim towards the released oocyte in order to fertilize it. What two processes must spermatozoa first undergo before being able to fertilize the oocyte?
Capacitation and acrosome reaction. Spermatozoa are not able to fertilize the oocyte immediately upon arrival in the female tract but must undergo capacitation and acrosome reaction to acquire this ability.
After fertilization, the zygote will begin cleavage, forming a morula, and eventually a blastocyst. What part of the blastocyst will develop iinto the embryo proper?
Inner cell mass
Inner cell mass developes into the embryo proper while the outer cell mass forms the trophoblast which later contributes to placenta. The embryo proper will then give rise to the 3 germ layers.
A 31 y/o woman who has missed her last 2 menstrual cycles presentswith severe lower abdominal pain and uterine hemorrhage. You suspect ectopic cavity. What is the most common location of blastocyst implantation in ectopic pregnancies?
Ampulla of uterine tube
What is the epiblast?
Derives from the embryoblast, and these are high columnar cells adjacent to the amniotic cavity
What is the hypoblast?
Cuboidal cells adjacent to blastocyst cavity
What is the bilaminar germ disc?
It is the result of the blastocyst at day 7.5. Look at picture.
What is the amniotic cavity?
It is the cavity that is surrounded by the epiblast.
Where do the primary villi come from?
The cytotrophoblast cell columns surrounded by syncytiotrophoblast
When the two pronuceli intermingle it is said to be a diploid cell why is this?
It is diploid because there are 46 chromosones in the cell
What is an important event that needs to occur for implantation?
Hatching from the zona pellucida coat is required for implantation
What is the primitive yolk sac lined by?
The exocoelomic membrane
Why are the trophoblastic lacunae important?
The mothers blood will eventually be found in these
amniotic cavity
Amniotic cavity appears as a small cleft, amnioblasts secrete fluid in the epiblast on week 2
bilaminar germ disc
consists of a layer of columnar epiblast cells and cuboidal hypoblast cells
primitive yolk sac/exocoelomic cavity
Flat cells form the exocoelomic membrane which line the exocoelomic cavity or the primitive yolk sac on day 9
The blastocyst differentiates into what two germ layers?
Epiblast and hypoblast
What is important about the syncytiotrophoblast?
These are the site of the lacunae which are the embryonic blood vessels
What forms from the intermediate mesoderm?
genitourinary system
What forms from the paraxial mesoderm?
Somites
Scleratome - bone and cartilage
Dermatome - dermis
Myotome - muscle
What forms from lateral plate mesoderm?
bone and cartilage of connective tisse
What are the main structures formed from the endoderm?
Lining of the respiratory and GI tract
