Embryology 1. 1 Flashcards
What are the three phases of the development of a human?
Pre-embryonic phase: 0-3 weeks
Embryonic phase:
4-8 weeks
Foetal phase:
9-40 weeks
What are the gametes?
sperm (formed in gonads a.k.a testis) and ovum (formed in ovaries)
What does a testis contain?
number of tubules called seminiferous tubules
What are within the seminiferous tubules?
little cells called spermatogonia - which are now able to divide and form your sperms
What are inside the ovaries?
follicles and inside follicles your oogonia (parent cell) will divide to form the ovum
What are the parent cells that form sperm in males and ovum in women?
spermatogonia and oogonia
How many chromosomes do the sperm and ovum have?
44 autosomes and one pair of sex chromosomes.
X and Y - male
X and X- female
What happens during meiosis?
Meiosis 1 where each of the parent cells has divided into two daughter cells.
Then daughter cells there undergo meiosis 2 in order to form four daughter cells.
What is the outcome of spermatogenesis?
4 sperms
Genetic makeup of 22 X or 22 Y
When do the follicles in a woman’s ovary start forming?
when the mother herself was in utero.
From primary follicles the oogonium undergo meiosis 1 and then get arrested.
What is the outcome of oogenesis?
under the influence of hormones such as oestrogen and progesterone - the follicle undergoes meiosis 2.
Each follcile gives rise to 3 polar bodies and one ovum.
Why are siblings different?
Each sperm and ovum has a unique genetic makeup
How is a zygote formed?
several sperms surround the ovum but only one penetrates.
Pronucleus of sperm enters and fuses with the pronucleus of ovum to give a diploid cell called the zygote (46 chromosomes).
Where are the cytoplasmic organelles from in the zygote?
derived from ovum
