The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
The normal human menstrual cycle is 28 days, but no woman is always precisely regular, and cycles as short as 21 days or as long as 35 days are not abnormal. Menstruation is the shedding of the uterine lining, the endometrium.
The menstrual cycle begins with about five days of menstruation, followed by a proliferative phase during which ovulation occurs. The proliferative phase lasts to about the fourteenth day, and then a secretory phase begins.
At the end of menstruation, just at the beginning of the proliferative phase, the endometrium is thin, and the ovary is dormant. With the production of gonadotropic hormones from the pituitary gland, an ovarian follicle (occasionally more than one) ripens in one of the ovaries. This ovarian follicle contains the ovum. Cells surrounding the ovum multiply, and secrete an estrogenic hormone, estradiol This hormone causes multiple changes to occur in the endometrium, so that it becomes thicker and more vascular.
At about mid-cycle ovulation occurs: The ovum is released from the follicle and received into the fallopian tube, down which it is carried to the uterus.
If the ovum is fertilized during the proliferative phase, it reaches the uterine cavity at a time when the endometrium is in the secretory phase, and the ovum embeds itself in the endometrium and starts its growth. If the ovum is not fertilized the endometrium breaks down and menstruation occurs. The disintegrating endometrium is shed, together with some blood. The endometrium contains plasmin, an enzyme that dissolves blood clots, so that the menstrual discharge is normally fluid. The total blood loss does not generally exceed 1.69 oz (50 ml).