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Menstrual Disorders - Introduction

From DrKoop's partner site on erectile dysfunction, ErectileDysfunctionConnection.com

(Page 3)


Placenta Click the icon to see an image of the placenta.
Follicle development Click the icon to see an image of the corpus luteum.

If the egg is not fertilized, the corpus luteum degenerates into a form called the corpus albicans, and estrogen and progesterone levels drop. Finally, the endometrial lining sloughs off and is shed during menstruation.

Typical Menstrual Cycle

Menstrual Phases

Typical No. of Days

Hormonal Actions

Follicular (Proliferative) Phase

Cycle Days 1 through 6: Beginning of menstruation to end of blood flow.

Estrogen and progesterone start out at their lowest levels.

FSH levels rise to stimulate maturity of follicles. Ovaries start producing estrogen and levels rise, while progesterone remains low.

Cycle Days 7 - 13: The endometrium thickens to prepare for the egg implantation.

Ovulation

Cycle Day 14:

Surge in LH. Largest follicle bursts and releases egg into fallopian tube.

Luteal (Secretory) Phase, also known as the Premenstrual Phase

Cycle Days 15 - 28:

Ruptured follicle develops into corpus luteum, which produces progesterone. Progesterone and estrogen stimulate blanket of blood vessels to prepare for egg implantation.

If fertilization occurs:

Fertilized egg attaches to blanket of blood vessels that supplies nutrients for the developing placenta. Corpus luteum continues to produce estrogen and progesterone.

If fertilization does not occur:

Corpus luteum deteriorates. Estrogen and progesterone levels drop. The blood vessel lining sloughs off and menstruation begins.
Menstrual cycle - interactive tool Click the icon to see an animation about the menstrual cycle.

Stages and Features of Menstruation

What is Menstruation? Menstruation, also called a "period," is the cyclical flow of blood from the uterus in women between the ages of puberty and menopause.

Onset of Menstruation (Menarche). Previous evidence had set the onset of menstruation, called the menarche, at an average of age 12 or 13. Recent studies, however, set the time of onset earlier by about 1 year in Caucasian girls and 2 years in African American girls. Currently, the youngest possible age for normal puberty is 7 years old for Caucasians and 6 years old for African Americans, down from a previous low of 8 years for both.

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