Week 2 gametogenesis Flashcards Preview

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Flashcards in Week 2 gametogenesis Deck (14):
1

PGCs- Primordial Germ Cells

move from epiblast to gonads from weeks 2-5
enriched with alkaline phosphate

2

genital ridge

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

3

teratoma

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

4

mitotic germ cells

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

5

meiosis

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

6

synapsis

made up of two pairs of sister chromatids crossing over
matched set of 4 chromatids: TETRAD

7

crossing over

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

8

oogenesis

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

9

activity of primary oocyte to secondary oocyte

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

10

spermatogenesis

the constant production and maturation of sperm

11

spermatagonia

Stem cell (diploid) renewal and progression into meiosis

12

spermatocyte

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

13

spermatid

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.

14

sperm

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