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A study of girls in Istanbul, Turkey, in 2011 found the median age at menarche to be 12.7 years. [ better source needed ] [ 9 ] In the United States, an analysis of 10,590 women aged 15–44 taken from the 2013–2017 round of the CDC's National Survey of Family Growth found a median age of 11.9 years (down from 12.1 in 1995), with a mean of 12 ...
Diagram illustrating how the uterus lining builds up and breaks down during the menstrual cycle Menstruation (also known as a period, among other colloquial terms) is the regular discharge of blood and mucosal tissue from the inner lining of the uterus through the vagina. The menstrual cycle is characterized by the rise and fall of hormones. Menstruation is triggered by falling progesterone ...
Menstrual cycle The menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of the female reproductive system that makes pregnancy possible. The ovarian cycle controls the production and release of eggs and the cyclic release of estrogen and progesterone. The uterine cycle governs the preparation and maintenance of the lining of the ...
The normal level of hemoglobin (an oxygen-transport protein found in red blood cells) for women is 12.0 to 15.5 g/dL (for men, 13.5 to 17.5 g/dL). [ 51 ] [ 52 ] [ 53 ] Women's hearts have finer-grained textures in the muscle compared to men's hearts, and the heart muscle 's overall shape and surface area also differs to men's when controlling ...
Due to its image (b) in the ground plane, a monopole antenna (a) has the same radiation pattern over perfect ground as a dipole antenna (c) in free space with twice the voltage In telecommunications and antenna design, an image antenna is an electrical mirror-image of an antenna element formed by the radio waves reflecting from a conductive ...
The ovaries are small, paired gonads located near the lateral walls of the pelvic cavity. These organs are responsible for the production of the egg cells (ova) and the secretion of hormones. The process by which the egg cell (ovum) is released is called ovulation .
Primary amenorrhea is defined as an absence of secondary sexual characteristics by age 13 with no menarche or normal secondary sexual characteristics but no menarche by 15 years of age. [3] It may be caused by developmental problems, such as the congenital absence of the uterus, failure of the ovary to receive or maintain egg cells , or delay ...
The point at which these two original epithelia meet is called the original squamocolumnar junction. [ 15 ] : 15–16 New studies show, however, that all the cervical as well as large part of the vaginal epithelium are derived from Müllerian duct tissue and that phenotypic differences might be due to other causes.