Menstrual Cycle
Definition
The menstrual cycle is a series of changes that occur in the ovaries and uterus over approximately
28 days to prepare for fertilisation and pregnancy.
Ovarian Cycle
FSH (Follicle Stimulating Hormone)
• Produced by the pituitary gland.
• Stimulates the development of the Graafian follicle in the ovary.
Oestrogen
• Produced by the Graafian follicle.
• Stimulates the thickening of the endometrium.
• Makes the endometrium:
o Thicker
o More vascular (increased blood supply)
1
, o More glandular
Ovulation
Definition:
The release of a mature ovum from the Graafian follicle in the ovary.
• Occurs about every 28 days.
• Usually occurs around day 14.
• The ovum is collected by the fallopian tube.
LH (Luteinising Hormone)
• Produced by the pituitary gland.
• Causes the ruptured Graafian follicle to form the corpus luteum.
Corpus Luteum
Definition:
The structure formed from the ruptured Graafian follicle after ovulation.
• Secretes progesterone.
Progesterone
• Maintains the endometrium.
• Maintains pregnancy if fertilisation occurs.
Uterine Cycle
Role of Oestrogen
Prepares the uterus for implantation by making the endometrium:
• Thicker
• More vascular
• More glandular
Role of Progesterone
2
Definition
The menstrual cycle is a series of changes that occur in the ovaries and uterus over approximately
28 days to prepare for fertilisation and pregnancy.
Ovarian Cycle
FSH (Follicle Stimulating Hormone)
• Produced by the pituitary gland.
• Stimulates the development of the Graafian follicle in the ovary.
Oestrogen
• Produced by the Graafian follicle.
• Stimulates the thickening of the endometrium.
• Makes the endometrium:
o Thicker
o More vascular (increased blood supply)
1
, o More glandular
Ovulation
Definition:
The release of a mature ovum from the Graafian follicle in the ovary.
• Occurs about every 28 days.
• Usually occurs around day 14.
• The ovum is collected by the fallopian tube.
LH (Luteinising Hormone)
• Produced by the pituitary gland.
• Causes the ruptured Graafian follicle to form the corpus luteum.
Corpus Luteum
Definition:
The structure formed from the ruptured Graafian follicle after ovulation.
• Secretes progesterone.
Progesterone
• Maintains the endometrium.
• Maintains pregnancy if fertilisation occurs.
Uterine Cycle
Role of Oestrogen
Prepares the uterus for implantation by making the endometrium:
• Thicker
• More vascular
• More glandular
Role of Progesterone
2
