Ovulation, Fertilization and Implantation Flashcards
(20 cards)
What is the gestational age?
Duration of pregnancy dated back to FIRST DAY OF LMP
How long does gestational age preceed ovulation by?
around 13/14 days
Till when is it an embryo?
10 weeks
How many chromosomes do PRIMARY oocytes have?
diploid number (46,xx)
What happens during the follicular phase of the menstrual cycle?
several primary oocytes mature under the influence of FSH, completing meiosis 1
Secondary oocytes are then formed
How many chromosomes do SECONDARY oocytes have?
haploid (23,x)
What do secondary oocytes become after extrusion of the first polar body?
mature follicles called Grafian follicles
What happens to secondary oocytes as they enter meiosis II?
they are suspended at metaphase
A dominant follicle is selected
What happens when LH secretion occurs?
ovulation occurs, which expels the follicle into the abdominal cavity
When does fertilization of a mature ovum occur?
within the first few hours of ovulation
What happens to the secondary follicle/ovum when fertilization has occurred?
completes meiosis II
Male and female haploids fuse to form the zygotes, which will have how many chromosomes?
diploid number (46,xx or 46,xy)
What is the name for the daughter cells made by the dividing zygote?
blastomeres
Where does the zygote division into blastomeres occur?
fallopian tube
When blastomeres continue to divide, they form a solid ball - this is known as what?
morula
When does the morula enter the uterine cavity?
day 3-4
What does fluid accumulation do to the morula?
changes it to a blastocyst
Where does implantation occur?
upper posterior uterine wall
What happens during implantation
Just beforehand, a small group of cells surrounding the blastocyst (zona pellucida) vanishes, and the blastocyst sticks to the endometrium - this is called APPOSITION
The endometrium is then invaded by the blastocyst
When is implantation usually completed by?
day 24/25 gestation
10-11 days post conception