Key concepts: Fertilisation and implantation

Question 1

conditions associated

Answer 1

ectopic pregnancy
spontaneous aboriton

Question 2

label the fallopian tube from proximal to distal in relation to the ovaries

Answer 2

fimbriae
infundibulum
ampulla
isthmus

Question 3

cumulus oophorus

Answer 3

cells on the outside of the oocyte that were pulled away from the inside of the follicle when it burst

Question 4

label an oocyte outside to inside

Answer 4

corona radiata
zona pellucida
cortical granules
nucleus
cytoplasm

Question 5

oocyte ploidy

Answer 5

haploid

Question 6

spermatozoa ploidy

Answer 6

haploid

Question 7

corona radiata

Answer 7

outer layer of cumulus cells

Question 8

zona pellucida

Answer 8

outer glycoprotein coat that surrounds the plasma membrane

Question 9

cortical granules

Answer 9

enzyme packets within the cell

Question 10

label sperm from head to tail

Answer 10

head containing the acrosome then nucleus
middle containing mitochondria in a spiral shape tail/ flagellum

Question 11

tail/flagellum

Answer 11

propels sperm towards the egg

Question 12

mitochondria in sperm

Answer 12

for energy

Question 13

acrosome

Answer 13

contains enzymes in the head of the sperm

Question 14

what are the 6 stages of fertilisation

Answer 14

sperm transport
sperm capacitation
sperm-oocyte interaction
sperm-oocyte fusion
completion of meiosis 2
zygote formation and implantation

Question 15

3 stages of sperm transport

Answer 15

vaginal
cervix
uterus

Question 16

vaginal sperm transport

Answer 16

where ejaculate is deposited
coagulates to form an alkaline loose gel
protects against the acidic environment of the vagina and immunological response

Question 17

cervix sperm transport

Answer 17

cervical mucus and high levels of oestrogen cause sperm to change microstructure of the mucus
allowing easy passage

Question 18

uterus sperm transport

Answer 18

uterine contractions to propel the sperm to the uterus

Question 19

sperm capacitation

Answer 19

epithelial interactions between the sperm ad uterine wall will destabilise the plasma membrane of the sperm
acrosomal reaction occurs

Question 20

what happens in the acrosomal reaction

Answer 20

glycoprotein coat covering the acrosome is removed
sperm plasma and acrosomal membrane will fuse
enzyme release from acrosome (across, hyaluronidase and hexosaminidase)
increase in CatSper channels on the flagellum
causing Ca2+ influx and sperm motility is hyper activated

Question 21

components of the sperm oocyte interactions

Answer 21

corona radiata
zona pellucida

Question 22

what occurs in the sperm interaction with the corona radiata

Answer 22

capacitated sperm pass through
hyaluronidase dissolves hyaluronic acid that cements the corona radiata cells

Question 23

what occurs in the sperm interaction with the zona pellucida

Answer 23

sperm penetrates here
due to the acorn released from acrosome
made up of 4 main glycoproteins ZP1,2,3,4
ZP3 proteins only binds to the receptors on the surface of human sperm

Question 24

sperm oocyte fusion

Answer 24

cortical reaction occurs
sperm fuses with the cell membrane of the oocyte
causes fast block to polyspermy: Na+ channels allow influx into cells, causes depolarisation, repels sperm
triggers SER to increase Ca2+ in the eggs cytosol
causes release of lysosomal enzymes in cortical granules
initiating the zona reaction, slow polyspermy block as cortical granules harden the oocyte membrane
release of hydrolytic enzymes further degrade the zona pellucida
stimulates exocytosis of cortical granules to harden oocyte membrane
impenetrable to further sper m

Question 25

completion of meiosis 2

Answer 25

oocyte completes meiosis 2 forms a definitive ovum and a polar body polar body is degraded

Question 26

when is the zygote formed

Answer 26

when the pronucleus of ovum and sperm fuse

Question 27

zygote division

Answer 27

by mitosis in the fallopian tubes morula, 16 cells day 3-4 blastocyst day 5 implantation then occurs day 7-8 blastocyst burrows into the uterine lining

Question 28

cleavage definition

Answer 28

cell division by mitosis in absence of cell growth until the 16 cell stage

Question 29

how many cells in morula

Answer 29

16

Question 30

morula to blastocyst

Answer 30

when morula becomes leaky and fluid filled cavity the zona pellucida disintegrates blastocyst then swept by the cilia and contractions

Question 31

layers of the blastocyst

Answer 31

trophoblast embryo blast

Question 32

inner cell mass

Answer 32

embryoblast becomes the bilaminar disc

Question 33

outer cell mass

Answer 33

cytotrophoblast and synchiotrophoblast

Question 34

implantation

Answer 34

thickening of the endometrium blastocyst rests on the endometrium trophoblast extends finger like projections that burrow into the endometrium implantation has occurred