Biology Reference
In-Depth Information
the production of LH and FSH by the pituitary and the production of
GnRH by the hypothalamus. After ovulation, LH supports the
development of the empty ovarian follicle into the corpus luteum (yellow
body), which secretes estrogen and progesterone to support the
endometrium, and inhibin to block the production of FSH by the
pituitary. The rising levels of progesterone and estrogen block the
production of GnRH, LH, and FSH, preventing the induction of
follicular development until the result of the previous ovulatory event is
apparent. If fertilization and implantation occur, the chorion (one of
the extraembryonic membranes of the new embryo) assumes
responsibility for the maintenance of the endometrium. If not, the
degeneration of the corpus luteum ensures that the endometrium is
shed, and the cycle begins again. These events are summarized in
Figure 9-4.
60
60
Anterior Pituitary
Hormones
50
50
40
40
30
30
20
20
10
10
0
0
1 4 7 0 3 6 9 2 5 8
Menstrual cycle (days)
200
20
Ovarian
Hormones
160
16
120
12
80
8
40
4
0
0
1 4 7 0 3 6 9 2 5 8
Menstrual cycle (days)
Follicle
Ovulation
Corpus Luteum
Ovary
Uterine
Endometrium
1
4
7
10
13
16
19
22
25
28
Menstrual cycle (days)
FIGURE 9-4.
Human menstrual cycle. The upper panels show the levels of the hormones LH, FSH, estrogen, and
progesterone; and the lower panel shows the response of the ovarian follicle and uterine lining.
Search WWH ::




Custom Search