Cell Bio Lecture 12 - Early Development 1 Flashcards
When is it called an embryo and when is it called a fetus?
0-8 weeks is an embryo, 9-38 is a fetus.
What did thalidomide teach developmental biologists?
Gave them a timetable for human embryonic development
What is gametogenesis?
The formation of fully-developed gametes.
How long does it take for sperm development (spermiogenesis)?
Three days
What is the site of a vasectomy?
The vas defrens
What forms the acrosome of the sperm?
The Golgi
What is in the mid-piece of the sperm?
Mitochondria
When in a male’s lifetime are sperm produced?
From puberty onward.
At what point in the cell cycle is the primary oocyte arrested?
Prophase I
At what point in the secondary oocyte arrested?
Metaphase II
What hormone causes ovulation?
LH surge
What are the cumulus oophorus?
The cells that have direct cytoplasmic bridges with the mature oocyte to provide nourishment and hormones.
Describe the process of follicle maturation.
GnRH stimulates FSH secretion, which stimulates 4-12 primordial follicles to grow and secrete estrogen. The fastest growing follicle secretes estrogen, which downregulates GnRH (and FSH), but because it has more FSH receptors, it wins the race. This follicle continues to mature; complete maturation takes 2-3 cycles.
Describe the process of ovulation (when the Graafian follicle expels the secondary oocyte).
FSH drives estrogen levels, and when estrogen hits a threshold, LH surge happens. LH surge triggers release of the primary oocyte from prophase I, and it quickly enters meiosis II and arrests at metaphase. This is now a secondary oocyte within a Graafian follicle. Prostaglandins like PGE2 cause the follicle to rupture, and the oocyte is expelled by contraction of the smooth muscle-like theca cells.
How long after the LH surge does ovulation occur?
12-24 hours
