The Menstrual Cycle Introduction

Question 1

The development of a mature oocyte requires

Answer 1

the endocrine interactions of the menstrual cycle.

Question 2

The length of the menstrual cycle (Latin = mensis = ‘month’) is the

Answer 2

number of days between the first day of menstrual bleeding of one cycle to the onset of menses of the next cycle and has an average duration of ~29.5 days or approximately one month (Figure 13).

Question 3

However, on an individual basis, the actual duration of the menstrual cycle varies with only __________ of all cycling women having a 29.5 day cycle.

Answer 3

10%-15%

Question 4

Most women who menstruate regularly have cycles that last from

Answer 4

25-30 days in length with older women having shorter cycles than younger women.

Question 5

The key to fertility is not having a cycle length of exactly 29.5 days but consistently having cycles of the same duration. Erratic menstrual cycle lengths in the same woman are associated

Answer 5

with infertility.

Question 6

The menstrual cycle is divided into the following two major phases:

Answer 6

a. The follicular phase

b. The luteal phase

Question 7

The follicular phase lasts approximately 14 days during which time there is

Answer 7

a daily increase in follicular growth and estrogen production.

Question 8

The length of the follicular phase appears to depend on the rate at which the

Answer 8

principal preantral follicle matures since it is the main source of estrogen and therefore a major regulator of cycle length.

Question 9

Menstruation occurs at the beginning of the

Answer 9

follicular phase and the day on which menses first appears is considered Day 1 of the menstrual cycle.

Question 10

On the 14 day of a 28-day menstrual cycle, ovulation occurs and the

Answer 10

follicle is transformed into the corpus luteum.

Question 11

Ovulation marks the end of the

Answer 11

follicular phase and the beginning of the luteal phase.

Question 12

The onset of the LH surge precedes

Answer 12

ovulation by 36 hours and LH levels peak 10 to 12 hours prior to ovulation.

Question 13

The luteal phase is associated with increasing production of

Answer 13

progesterone and some estrogen that prepares the uterus for implantation.

Question 14

The luteal phase is relatively constant in all women and will end in approximately

Answer 14

14 days with the appearance of menses if implantation does not occur. The cycle will repeat with the resumption of a new follicular phase.