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 make pregnancy possible. Naturally occurring hormones drive
two concurrent and coordinated cycles that last about 28 days. The
ovarian cycle controls the production and release of eggs and the
release of the hormones estrogen and progesterone. The uterine cycle
governs the preparation and maintenance of the lining of the uterus
(endometrium) to receive a fertilized egg. Menstruation, a "period" in
common parlance, begins on day one of the cycle, and lasts for about
five days. Around day fourteen, an egg is usually released from the
ovary. Estrogen stimulates the uterus lining to thicken to accommodate
an embryo should fertilization occur. If implantation does not occur,
the lining is released during menstruation. Menarche (the first period)
usually occurs around age twelve, and menstrual cycles usually continue
for 30–45 years until menopause.
Read more: <https://en.wikipedia.org/wiki/Menstrual_cycle>
Today's selected anniversaries:
English Civil War: Royalist troops stormed and captured the
Parlimentarian stronghold of Bolton, leading to a massacre of defenders
and local residents.
Mozaffar ad-Din, Shah of Persia, granted exclusive rights to
prospect for oil in the country to William Knox D'Arcy.
The rise of Neville Chamberlain culminated with his accession
as Prime Minister of the United Kingdom.
After 21 years of restoration work, Leonardo da Vinci's mural
painting The Last Supper, in Milan, Italy, was returned to display.
Wiktionary's word of the day:
(weaponry, obsolete, rare) The study of artillery; the practice of using
artillery as a weapon.
Wikiquote quote of the day:
Never say "no" to adventures. Always say "yes", otherwise
you’ll lead a very dull life.
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