|Estrogen is the major female sex hormone secreted primarily by the ovaries and in small amounts by the adrenal gland. It plays an important role in the onset of puberty, development of secondary sexual characteristics, such as breasts, and pubic and armpit hair. Estrogen also helps regulate the menstrual cycle and also controls breast changes during pregnancy.A journalÂ is aÂ periodical publicationÂ intended to further progress ofÂ science, usually by reporting newÂ research. Most journals are highly specialized, although some of the oldest journals publish articles, reviews, editorials, short communications, letters, andÂ scientific papersÂ across a wide range of scientific fields. Journals contain articles that peer reviewed, in an attempt to ensure that articles meet the journal's standards of quality, and scientificÂ validity. Each such journal article becomes part of the permanent scientific record.