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Amazing women! | the art of menstruation | artists (non-menstrual) | asbestos | belts | bidets | founder bio | Bly, Nellie | MUM board | books: menstruation and menopause (and reviews) | cats | company booklets directory | contraception and religion | costumes | menstrual cups | cup usage | dispensers | douches, pain, sprays | essay directory | extraction | famous women in menstrual hygiene ads | FAQ | founder/director biography | gynecological topics by Dr. Soucasaux | humor | huts | links | masturbation | media coverage of MUM | miscellaneous | museum future | Norwegian menstruation exhibit | odor (olor)| pad directory | patent medicine | poetry directory | products, current | religion | your remedies for menstrual discomfort | menstrual products safety | science | shame | slapping, menstrual | sponges | synchrony | tampon directory | early tampons | teen ads directory | tour of the former museum (video) | underpants directory | videos, films directory | Words and expressions about menstruation | Would you stop menstruating if you could? | What did women do about menstruation in the past? | washable pads
More articles by Dr. Soucasaux: Anatomical drawings - Anovulatory cycles - Archetypal aspects of the female genitals - The breasts: some morphological aspects - Colposcopy - Comments on the corpus luteum and related aspects - The curious relations between androgens and estrogens in women - Endocrinology of menstruation - The Fallopian tubes - Female sexual response - The Gräfenberg Spot (G-Spot) - The Gynecologic Palpation (descendant of "The Touch") - Gynecological assistance: the three basic areas - Gynecology and Gynecologic Surgery - Gynecologist versus obstetrician: what lies behind the combination? - "Gyneco-obstetric-surgical" stubborness and the perpetuation of one of the greatest mistakes of women's medicine - Hypermenorrhea and/or Menorrhagia (Prolonged and/or Excessive Menstrual Bleedings) - Hypertrichosis, Hirsutism and Androgenic Manifestations in Women - Mayer-Rokitansky-Kuster-Hauser (MRKHauser) Syndrome - Menstrual toxin: An old name for a real thing? - Nature and the ovaries - On the Strange Nature of the Ovaries - Oral hormonal contraceptives (the "Pill") - The Ovaries: Some Functional and Archetypal Considerations - Peculiarities of the Female Genitals' Sensory Innervation - Physiology of menstruation - Polycystic ovaries syndrome - The Possibility of Becoming Pregnant, Its Implications for Women, and Abortion - Premenstrual congestion of the breasts - Premenstrual syndrome (PMS) - The Psychology of Gynecology part 1 (part 2) - Psychosomatic and symbolic aspects of menstruation - Psychosomatic gynecology - Some Details on the Function of the Hypothalamus-Pituitary-Ovaries Axis - Stanislav Grof's Perinatal Matrixes of the Unconscious and Women's Medicine - Symmetric Patterns in the Female Genitals - Thoughts on Female Sexual Psychology - Uninterrupted use of hormonal contraceptives for menstrual suppression: why I do not recommend it - The uterine cervix - Uterine contractility - The Uterus and the Female "Passive-Active" - Women's corporeal consciousness and experience - Women's Experience of the Breasts - Women's Undesired Pregnancies and Women's Right to Abortion and see his Art of Menstruation


The Physiology of Menstruation

Dr. Nelson Soucasaux, Brazilian gynecologist

Of all organs of the body, the uterus is the only one whose inner lining mucosa is almost entirely expelled and reconstructed periodically, both phenomena taking place at each ovarian cycle. With the purpose of facilitating the periodic elimination of the endometrium that undergoes regression, shrinkage and necrosis at the end of each cycle, the uterus also exhibits the unique peculiarity of physiologically bleeding. The endometrial histo-physiology is entirely controlled by the ovarian hormones along the cycle. Of all tissues of the woman's body, the endometrium is the one that, throughout de ovarian cycle, more perfectly reflects the levels in the production of estrogens and progesterone.

The estrogens are responsible for the process of proliferation and growth of the endometrium, a process that begins immediately after menstruation and by means of which a new endometrium is constructed at each cycle. As it is widely known, the estrogens cause a strong proliferative effect upon the tissues of the woman's sexual organs. The estrogenic action on the endometrium results on great glandular proliferation and great increase in thickness, as well as the development of its vascularization.

Progesterone is mostly responsible for the secretory transformation of the endometrium, that occurs during the second phase of the ovulatory cycles. Under the effect of progesterone, the proliferative activity of the endometrial glands is greatly reduced, and these glands begin producing nourishing substances, which also begin to appear in the endometrial connective tissue. The progesteronic action upon the endometrium has two purposes: the first can be regarded as mostly "medical", and the second as essentially reproductive. The "medical" purpose is to oppose to some excessive proliferative effects of the estrogens, preventing the appearance of endometrial hyperplasic alterations ( progesterone has a strong anti-proliferative effect on the epithelium of the endometrial glands ). The reproductive purpose is to create, in the endometrium, the ideal conditions for the implantation and development of the egg.

In the absence of pregnancy, at the end of each ovulatory cycle, the menstrual desquamation of the endometrium is triggered by the sudden fall in the levels of progesterone and estrogens that result from the involution of the corpus luteum. On the other hand, at the end of each anovulatory cycle, the exclusive estrogenic fall, all by itself, also causes the menstrual desquamation of the endometrium. In both ovulatory and anovulatory cycles, the sudden fall of the ovarian hormones gives rise to regressive and necrotic phenomena in the endometrium. By means of complex biochemical and vascular mechanisms, these phenomena result on the menstrual disintegration and elimination of this tissue. It is important to emphasize that, though menstruation is triggered by the sudden hormonal fall, its occurrence is only possible due to the very peculiar pattern that characterize the endometrial vascularization and blood supply.

We have already said that, in anovulatory cycles (monophasic), only the estrogenic fall, all by itself, triggers menstruation, while in ovulatory cycles (biphasic), the menstrual phenomenon is triggered by the progesteronic-estrogenic sudden fall that results from the involution of the corpus luteum. Clinically we also verify that, in the absence of pregnancy and acting upon an endometrium previously stimulated by the estrogens, the exclusive progesterone withdrawal equally causes the coming of menstruation - even if there is no simultaneous fall in the estrogenic levels. The usual medicinal triggering of menstruation a few days after interrupting the use of progesterone or synthetic progestogens is based on this fact.

The endometrium is the tissue that covers the cavity of the uterine corpus, being endowed with a highly complex and organized histological structure. It is constituted by a stroma of connective tissue containing an enormous number of tubular-shaped glands, and its blood supply is provided by an intricate vascular system. The glands are lined by a single layer of columnar epithelial cells and open on the endometrial surface, which is lined by the same kind of epithelium. Under the influence of progesterone, its stroma also acquires secretory features. Two layers can be distinguished in the endometrium, the functional and the basal.

The functional layer is the one that is entirely expelled and reconstructed at each menstrual cycle, being able to reach considerable thickness when fully developed. It is highly responsive to the proliferative effect of the estrogens and to the secretory transformation induced by progesterone. Its blood supply (also developed by these hormones) is constituted by an intricate system of spiral arteries, capillary networks, veins, venous lakes and arteriovenous anastomosis. Of all structures that integrate this vascular system, the spiral arteries are the most important ones.

When the blood levels of the ovarian hormones fall, the endometrial functional layer immediately exhibits signs of regression, shrinkage and atrophy. This results in the formation of toxic and vasoactive substances which, by local action, trigger the ischemic and hemorrhagic vascular phenomena that cause the necrosis and menstrual desquamation of this layer of the endometrium. Menstruation happens as a consequence of the very peculiar way through which the mentioned vascular system reacts to the endometrial regressive changes that result from the sudden fall of the ovarian hormones.

The basal layer of the endometrium possesses small thickness and is situated deeply, in direct contact with the myometrium. This layer does not desquamate during menstruation and provides the histologic elements from which a new functional layer grows when the menstrual bleeding ceases. The basal layer does not exhibit significative modifications during the cycle, and seems to be less responsive to the hormonal stimuli. Its blood supply is provided by another vascular system, constituted by small straight arteries. In this way, the basal layer does not undergo the necrotic, ischemic and hemorrhagic alterations of the menstrual period and, because of this, is always preserved.

The menstrual phenomenon depends on two fundamental factors, one of which is endocrine and the other vascular. The endocrine one, that consists on the sudden fall in the blood levels of the ovarian hormones, is the main triggering factor. The vascular reactions are a consequence of the involutive endometrial changes caused by the hormonal sudden fall.


The text above is an excerpt from my book "Os Órgãos Sexuais Femininos: Forma, Função, Símbolo e Arquétipo" ("The Female Sexual Organs: Shape, Function, Symbol and Archetype"). For more information on the book, see page http://www.nelsonginecologia.med.br/orgaos.htm of my Website http://www.nelsonginecologia.med.br

©Nelson Soucasaux, 1993, 2001

__________________________________________________________

Nelson Soucasaux is a gynecologist especially dedicated to clinical, preventive and psychosomatic gynecology. Graduated in 1974 by Faculdade de Medicina da Universidade Federal do Rio de Janeiro, Brazil, he is the author of several articles published in medical journals and of the books "Novas Perspectivas em Ginecologia" ("New Perspectives in Gynecology") and "Os Órgãos Sexuais Femininos: Forma, Função, Símbolo e Arquétipo" ("The Female Sexual Organs: Shape, Function, Symbol and Archetype"), published by Imago Editora, Rio de Janeiro, 1990, 1993.

Web site (Portuguese-English): www.nelsonginecologia.med.br

E-mail: nelsons@nelsonginecologia.med.br

NEWS | homepage | LIST OF ALL TOPICS | MUM address & What does MUM mean? | e-mail the museum | privacy on this site | who runs this museum?? |
Amazing women! | the art of menstruation | artists (non-menstrual) | asbestos | belts | bidets | founder bio | Bly, Nellie | MUM board | books: menstruation and menopause (and reviews) | cats | company booklets directory | contraception and religion | costumes | menstrual cups | cup usage | dispensers | douches, pain, sprays | essay directory | extraction | famous women in menstrual hygiene ads | FAQ | founder/director biography | gynecological topics by Dr. Soucasaux | humor | huts | links | masturbation | media coverage of MUM | miscellaneous | museum future | Norwegian menstruation exhibit | odor (olor)| pad directory | patent medicine | poetry directory | products, current | religion | your remedies for menstrual discomfort | menstrual products safety | science | shame | slapping, menstrual | sponges | synchrony | tampon directory | early tampons | teen ads directory | tour of the former museum (video) | underpants directory | videos, films directory | Words and expressions about menstruation | Would you stop menstruating if you could? | What did women do about menstruation in the past? | washable pads
More articles by Dr. Soucasaux: Anatomical drawings - Anovulatory cycles - Archetypal aspects of the female genitals - The breasts: some morphological aspects - Colposcopy - Comments on the corpus luteum and related aspects - The curious relations between androgens and estrogens in women - Endocrinology of menstruation - The Fallopian tubes - Female sexual response - The Gräfenberg Spot (G-Spot) - The Gynecologic Palpation (descendant of "The Touch") - Gynecological assistance: the three basic areas - Gynecology and Gynecologic Surgery - Gynecologist versus obstetrician: what lies behind the combination? - "Gyneco-obstetric-surgical" stubborness and the perpetuation of one of the greatest mistakes of women's medicine - Hypermenorrhea and/or Menorrhagia (Prolonged and/or Excessive Menstrual Bleedings) - Hypertrichosis, Hirsutism and Androgenic Manifestations in Women - Mayer-Rokitansky-Kuster-Hauser (MRKHauser) Syndrome - Menstrual toxin: An old name for a real thing? - Nature and the ovaries - On the Strange Nature of the Ovaries - Oral hormonal contraceptives (the "Pill") - The Ovaries: Some Functional and Archetypal Considerations - Peculiarities of the Female Genitals' Sensory Innervation - Physiology of menstruation - Polycystic ovaries syndrome - The Possibility of Becoming Pregnant, Its Implications for Women, and Abortion - Premenstrual congestion of the breasts - Premenstrual syndrome (PMS) - The Psychology of Gynecology part 1 (part 2) - Psychosomatic and symbolic aspects of menstruation - Psychosomatic gynecology - Some Details on the Function of the Hypothalamus-Pituitary-Ovaries Axis - Stanislav Grof's Perinatal Matrixes of the Unconscious and Women's Medicine - Symmetric Patterns in the Female Genitals - Thoughts on Female Sexual Psychology - Uninterrupted use of hormonal contraceptives for menstrual suppression: why I do not recommend it - The uterine cervix - Uterine contractility - The Uterus and the Female "Passive-Active" - Women's corporeal consciousness and experience - Women's Experience of the Breasts - Women's Undesired Pregnancies and Women's Right to Abortion and see his Art of Menstruation

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