Fertilisation, cleavage and implantation

zainaboshodi's version from 2015-04-21 12:12


Question Answer
Define fertilisation:When 2 gametes fuse to form a zygote.
What occurs in the first stage of gametogenesis?The secondary oocyte and first polar body are formed.
What occurs following fertilisation of the secondary oocyte?The mature oocyte and 2nd polar body are formed.
What occurs during ovulation?A surge in LH, degradation of the connective matrix of collagen and expulsion of the secondary from Graafian follicle into the peritoneal cavity.
How are oocytes transported down the fallopian tube?Peristalsis and cilia inside the tube.
How do the spermatoza mature in the fallopian tube?Capacitance and the acrosome reaction.
What sperm cells which have undergone capacitation display?Hyperactivated motility and a de-stabillized membrane to prepare for the acrosome reaction.
What are the physiological stimuli of the acrosome reaction?Zona pelluicda protein ZP3 and progesterone
What are the 3 barriers the sperm needs to pass through?Corona radiata, zona pellucida and oocyte cell membrane.
What does the sperm have to bind to on the oocyte cell membrane?Fusion with A Disintegrin And Matrix metalloproteinase (ADAM)
What occurs in the fast block mechanism to prevent polyspermy?Depolarisation of the oocyte outer membrane, sodium ions flood into the oocyte changing the charge from -70mV to +20mV.
What occurs in the slow block mechanism to prevent polyspermy? After 5 to 8 minutes, mediated by increase in intracellular calcium, cortical granules fuse with inner membrane. Releases lysosomal enzymes which alters the zona pellucida.
What are the dramatic changes that occur up on sperm and oocyte union?Oocyte membrane depolarisation, final meiotic division, restoration of diploidy, sex determination, genetic determination and initation of cleavage.
What is the morula?16 cell stage.
What does a blastocyst consist of?Fluid, inner cell mass and trophoblast.
How does the blastocyte bind to the endometrium?L-selectins on the trophoblast cells bind to carbohydrate ligands on the endometrium.
What does the trophoblast divide into and what are their functions?Cytotrophoblast - mitotically active, cells migrate to the syncytiotrophoblast. Syncytiotrophoblast - not mitotically active, form placental villi.
What does the embryoblast divide into and what do they do?Epiblast - columnar cells, endometrial side, form the blastocyst cavity, the amniotic cavity. Hypoblast - small cuboidal cells next to the blastocyst cavity.
What is the bilaminar embryonic disc?A disc consisting of 2 cavities and two layers of cells with the epiblast on top.

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