Development and Inheritance Flashcards
What happens during fertilization?
genetic material of sperm and oocyte merge into a single nucleus
When does fertilization occur?
12-24 hours after ovulation
What must happen before fertilization can occur?
capacitation
acrosomal reaction
what is capacitation?
weakening of cell membrane of spermatozoa head
where does capacitation happen?
female reproductive system
what is the acrosomal reaction?
sperm surrounds oocyte and releases hyaluronidase
what happens after hyaluronidase is secreted?
disruption of the corona radiate and the zona pellucida
what blocks polyspermy?
changing the location of the veils
what is polyspermy?
many sperm
How long do spermatozoa survive?
3-7 days
How long is the oocyte viable once ovulated?
24 hours
What day of the cycle should fertilization occur?
day 15
What happens when sperm enters the secondary oocyte?
fusion of male pronucleus and female pronucleus
what is a male pronucleus?
flagella is shed and head develops
what is a female pronucleus?
nucleus of female oocyte
What happens when the male pronucleus and female pronucleus fuse?
a zygote is formed with 46 chromosomes
How are dizygotic twins formed?
when the mother ovulates 2 oocytes and both are fertilized
Once a zygote is formed, it will undergo
a form of mitosis called cleavage
what is cleavage?>
1 celled zygote will duplicate and split into two cells
How long after fertilization does cleavage occur?
30 hours
what follows cleavage?
more and more cell division until a morula is formed
what is a Morula?
solid ball of blastomeres surrounded by the zona pellucida
Where is the morula?
fallopian tube headed for the uterus
What happens after 5 days of development?
a blastocyst is formed.
what is a blastocoele?
cavity that forms in the middle of the blastocyst
what is a trophoblast?
outer covering of cells on the blastocyst
what causes blastocoele?
movement of blastomeres
what is the embryoblast?
inner covering of cells on a blastocyst