Uterus and Uterine Cycle

Question 1

general functions of uterus

Answer 1

space for embryo impantation

home for fetal development

muscularture of uterine wall works to expel fetus

Question 2

3 layers of uterus

Answer 2

1. endometrium
2. myometrium
3. perimetrium

Question 3

endometrium

Answer 3

mucosa lined by simple, columnar

stratum basale = always present throughout the cycle

stratum functionale = layer that grows and is lost with every cycle

Question 4

myometrium

Answer 4

muscularis

very thick and vascular

smooth muscle interlaced with collagen fiberes

• largest smooth muscle fibers in the body can reach up to 1/2 mm and seen by naked eye
• 3 layers (middle circular, stratum vasculare, is the thickest and contains arcuate arteries)

Question 5

hormone regulation myometrium

Answer 5

estrogen = proliferation; maintains/increases contractility; formation of gap junctions; peak levels around 13-14day (mitogenic effect on endometrial lining)

progesterone = decrease contractility; peak levels around day 21 (differentiation effect on the endometrial lining)

relaxin = inhibits uterine contractions

oxytocin = stimulates uterine contractions

Question 6

perimetrium

Answer 6

serosa/adventitia (outer covering of uterus)

Question 7

phases of uterine cycle

Answer 7

1. menstrual (days 1-5)
2. proliferative (5-14)
3. secretory (15-26)
4. pre-menstrual (27-28)

Question 8

Menstrual phase

Answer 8

• tissue is crashing; hormone levels are very low; losing stratum functionale
• stroma filled with WBCs and RBCs
• columnar epithelium
• no mitoses

Question 9

proliferative phase

Answer 9

estrogen peaks –> estradiol rules

endometrium begins to thicken (1–>4mm)
- thickens in response to increased estradiol levels, which is produced from growing follicle

glands become narrow and straight without secretory activity (need progesterone to become active)

stroma proliferates

lots of mitoses

columnar epithelium both at surface and in glands

Question 10

secretory phase

Answer 10

estradiol

mostly progesterone

after ovulation…follicle transforms into corpus luteum…shifts hormone production from estradiol –> progesterone

endometrium thickens still (4–>6mm)

glands widen and start secreting nutreints and glycogen to foster implantation

stroma becomes swollen with fluid leaking out of vasculature

tall columnar

mitoses slows except for coiled arteries

at end of this phase = corpus luteum beings to degrade and progesterone and estrogen levels drop off

Question 11

pre-menstrual phase

Answer 11

still maintain thick endometrium and wide glands

but vasculature begins to break down…

so stroma becomes dense with WBCs and RBCs

epithelium = columnar

no mitoses