Name ____________________
Menstrual Cycle Lab
Regents Biology
Background information:
In order for embryonic growth & development to occur, the gametes (sex cells)
from each parent must meet at the appropriate time & in the proper environment. In
mammals, because the offspring develop internally, not only must the sperm & egg meet
at the appropriate time, the uterus must also be prepared to accept & nourish the fertilized
egg. In most mammals, this is accomplished by having a limited period of sexual
receptivity known as estrus. During estrus, the eggs are available to be fertilized and the
female is prepared to nourish the embryo(s).
Humans are different from most mammals in that the female is always sexually
receptive. However, her eggs are not always available for fertilization & development. A
sexually mature human female is capable of producing a mature egg about once every 28
days. Periodic changes in the uterine lining also occur. The cyclic series of changes in the
uterine lining is known as the menstrual cycle.
Because menstruation is the most visible part of the cycle, the first day of
menstruation is often referred to as day 1 of the cycle. During this time, the endometrium
(uterine lining) as well as some blood & body fluids are released through the vagina.
Menstruation will typically last about 5 days. The second stage of the menstrual cycle
is the follicle stage. During this time, an egg completes the maturation process. The third
phase of the cycle, ovulation is the shortest. It occurs around day 14 in a 28 day cycle.
The fourth phase of the cycle is the corpus luteum or luteal phase. It lasts 13-15 days.
At this time the lining is prepared to receive the zygote.
This 28 day cycle involves several different hormones. The main hormones are
involved in egg maturation & release & in preparing the uterus to receive the egg if
fertilized. These hormones are follicle stimulating hormone (FSH), luteinizing
hormone (LH), estrogen, & progesterone. A fifth hormone, human chorionic
gonadotropin (hcG) is released by the corpus luteum (the ruptured follicle) & is present
only if a woman becomes pregnant.
In this lab, you will create a series of graphs of the major hormones involved in
the menstrual cycle, the changes in uterine lining thickness & body temperature. You will
use these graphs to answer a series of questions regarding the human menstrual cycle &
pregnancy.
Materials
Graph paper
colored pencils
ruler or straight edge
Table 1: Hormone, Uterine lining & temperature data
Day
LH
FSH
Progesterone Estrogen
1
2
4
6
8
10
11
12
13
14
16
18
20
22
23
24
26
28
2
2
7
5
3
2
7
15
40
32
4
2
1
0.5
0.5
0.5
1
2
5
12
13
10
5
4
7
12
15
12
6
4
3
2
2
2
2
5
1
1
1
1
1
1
1
1
2
3
7
15
19
24
25
23
15
1
2
2
2
3
10
20
26
23
15
10
1
6
9
8
112
10
6
2
Uterine
Lining
Thickness
10
8
5
6
10
15
21
22
25
25
25
25
25
25
25
23
19
11
Temperature
98.0
98.1
98.2
97.8
98.0
98.2
98.1
97.9
97.8
98.8
98.6
98.7
98.6
98.5
98.6
98.4
98.3
98.0
LH= lutenizing hormone
FSH= follicle stimulating hormone
Hormones are measured in hormone units
Uterine lining is measured in uterine lining units
Temperature is measured in degrees Fahrenheit
Procedure
1. Using one sheet of graph paper, label the X axis Days & the Y axis Hormone
level.
2. Number the X axis 0-28 with each line equal to 1.
3. Number the Y axis 0-40 with each line equal to 1.
4. Title your graph Hormone Variations during the menstrual cycle.
5. Plot LH with a yellow pencil.
6. Plot FSH with a blue pencil.
7. Plot progesterone with a red pencil.
8. Plot estrogen with a green pencil.
9. In the space below the X axis of your graph, using the information provided in
the introduction, label the 4 phases of the menstrual cycle: menstruation,
follicle stage, ovulation, & corpus luteum stage.
10. Draw the following pictures of the follicle next to the appropriate data point
on your graph.
11. Using a second sheet of graph paper, label the X axis Days & the Y axis Uterine
lining thickness.
12. Number the X axis 0-28 with each line equal to 1.
13. Number the Y axis 0-25 with each line equal to 1.
14. Title your graph Uterine lining thickness during the menstrual cycle.
15. Plot Uterine lining thickness with an orange pencil.
16. In the space below the X axis of your graph, using the information provided in
the introduction, label the 4 phases of the menstrual cycle: menstruation,
follicle stage, ovulation, & corpus luteum stage.
17. Using a third sheet of graph paper, label the X axis days & the Y axis
temperature.
18. Number the X axis 0-28 with each line equal to 1.
19. Number your Y axis 97.5 to 99.0 with each line equal to 0.1.
20. Title your graph Temperature variation during the menstrual cycle.
21. Plot temperature with a brown pencil.
22. In the space below the X axis of your graph, using the information provided in
the introduction, label the 4 phases of the menstrual cycle: menstruation,
follicle stage, ovulation, & corpus luteum stage.
Questions
1. Since a woman is born with all of her primary oocytes (immature eggs), why must
she be especially careful about exposure to chemicals, radiation, or drugs even
before she becomes pregnant?
2. Use your Hormone Variations during the Menstrual Cycle Graph to answer the
following questions.
a. What is the function of LH?
b. What is the function of FSH?
c. What is the function of progesterone?
d. What is the function of estrogen?
e. What day does LH peak?
f. What day does FSH peak?
g. What day does progesterone peak?
h. What day does estrogen peak?
i. Why don’t all 4 hormones peak on the same day?
j. Which of the 4 hormones graphed are released by the pituitary gland?
k. Which of the 4 hormones graphed are released by the ovary?
3. On which day does the uterine lining reach its maximum thickness? Why must the
lining be thick at this point in the cycle?
4. Besides affecting the uterine lining, estrogen increases the senses of taste & smell.
a. During which phase of the menstrual cycle will a woman have heightened
taste & smell?
b. How would an increase in these senses be beneficial if conception occurs?
5. The corpus luteum (ruptured follicle) causes the release of progesterone from the
ovary. What would happen if fertilization had occurred but the corpus luteum was
not maintained beyond day 28 in the cycle?
6. Test kits are available for woman trying to conceive which predict ovulation one
day in advance. What hormone are these kits testing for?
7. A pregnancy test uses a hormone that is present only if a woman is pregnant to
confirm conception. What hormone is a pregnancy test indicating for?
8. Basal body temperature is another pregnancy indicator. If temperature remains
high for 21 days after fertilization this is considered a positive indication of
conception.
a. During which phase of the menstrual cycle does body temperature
increase?
b. During which phase of the menstrual cycle does body temperature drop?
c. Which hormone is causing the increase in body temperature?