All hens are chickens, but not all chickens are hens. Hens are exclusively female, while chickens can be male or female. Chickens are the species name for both hens and chickens
Cervical mucus plug forms during pregnancy to seal cervical canal. Composed of water, gel-forming-mucins, and vaginal flora. Mucins provide structural framework and determine elasticity
Moulting is the shedding of body parts for various purposes. Can involve shedding skin, feathers, or other external layers. Medieval term "mewing" refers to King's hawks during moulting
Sperm travels 15-18 cm from vagina to uterine tube. pH rises in vagina within 8 seconds after ejaculation. Semen becomes gel within minute, allowing swimming. Sperm can wait up to 5 days in reproductive tract
Women have millions of eggs in ovaries, which decrease to few hundred by adulthood. Approximately 400 eggs are released during reproductive years. Eggs travel through fallopian tubes to uterus during ovulation. Fertilization occurs within 24 hours after egg meets sperm
Monthly series of changes preparing body for pregnancy. Ovulation occurs each month, releasing egg into uterus. Periods last 2-7 days, occurring every 21-35 days. Menstrual cycles become more regular with age