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:

1644:

English Civil War: Royalist troops stormed and captured the Parlimentarian stronghold of Bolton, leading to a massacre of defenders and local residents. https://en.wikipedia.org/wiki/Storming_of_Bolton

1901:

Mozaffar ad-Din, Shah of Persia, granted exclusive rights to prospect for oil in the country to William Knox D'Arcy. https://en.wikipedia.org/wiki/D%27Arcy_Concession

1937:

The rise of Neville Chamberlain culminated with his accession as Prime Minister of the United Kingdom. https://en.wikipedia.org/wiki/Rise_of_Neville_Chamberlain

1999:

After 21 years of restoration work, Leonardo da Vinci's mural painting The Last Supper, in Milan, Italy, was returned to display. https://en.wikipedia.org/wiki/The_Last_Supper_%28Leonardo%29

_____________________________ Wiktionary's word of the day:

pyroballogy: (weaponry, obsolete, rare) The study of artillery; the practice of using artillery as a weapon. https://en.wiktionary.org/wiki/pyroballogy

___________________________ Wikiquote quote of the day:

Never say "no" to adventures. Always say "yes", otherwise you’ll lead a very dull life.   --Ian Fleming https://en.wikiquote.org/wiki/Ian_Fleming