Week 2 gametogenesis

Question 1

PGCs- Primordial Germ Cells

Answer 1

move from epiblast to gonads from weeks 2-5

enriched with alkaline phosphate

Question 2

genital ridge

Answer 2

primitive gonad, PGCs directed here with messengers to create mature gonads and to mature into sperm and eggs

Question 3

teratoma

Answer 3

PGC misdirected and then survive, differentiate into many different tissues and make huge growths found in mediastinum, sacrococcygeal and oral regions

Question 4

mitotic germ cells

Answer 4

proliferate immensely then are selectively killed by apoptosis
Oogonia (only undergo mitosis during embryo development)
Spermatogonia (during embryonic development and throughout adult life)
From 4,000 to 7 million
First overpopulated, then eliminated through apoptosis
Progenitor germ cells of future gametes

Question 5

meiosis

Answer 5

reduced csome number by half in gametes
only occurs in the reproductive organs
arrested in prophase 1 in females until puberty

Question 6

synapsis

Answer 6

made up of two pairs of sister chromatids crossing over

matched set of 4 chromatids: TETRAD

Question 7

crossing over

Answer 7

Nonsister chromatids break into two at the same spot
The 2 broken chromatids join together in a new way
A segment of one chromatid has changed places with the equivalent segment of its nonsister homologue
If there were no crossing over meiosis could only produce 2 types of gametes

Question 8

oogenesis

Answer 8

creating of haploid oocyte
2 million produced, 400 ovulated, 1 menstruated
meiosis 2 occurs only after puberty and upon fertilization

Question 9

activity of primary oocyte to secondary oocyte

Answer 9

primary oocyte breaks off asymmetrically into a polar body and a secondary oocyte. the polar body does not contain any mitochondria
the secondary oocyte undergoes meiosis 2 when it is fertilized

Question 10

spermatogenesis

Answer 10

the constant production and maturation of sperm

Question 11

spermatagonia

Answer 11

Stem cell (diploid) renewal and progression into meiosis

Question 12

spermatocyte

Answer 12

Cells enter meiosis (meiosis = a lessening) for reduction and division (two divisions in rapid succesion:1 diploid cell becomes 4 haploid cells).

Question 13

spermatid

Answer 13

After reduction & division, the haploid cells differentiate towards becoming mature sperm, a process called spermatogenesis, during which they acquire a tail (flagellum) and an acrosome that develops from the Golgi body.

Question 14

sperm

Answer 14

At completion of spermiogenesis, each spermatid disengages excess cytoplasm and is released into the lumen of the seminiferous tubule (spermiation).