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Females reach sexual maturity (puberty) between 8 and 18 months of age. There is a tremendous variability in the maturation age between breeds, and even within a breed of dog. [ 5 ] 1. Proestrus, in which eggs in the ovaries begin to mature and estrogen levels begin to rise, is the first stage of the reproductive cycle.
A female dog is usually diestrous (goes into heat typically twice per year), although some breeds typically have one or three cycles per year. The proestrus is relatively long at 5 to 9 days, while the estrus may last 4 to 13 days, with a diestrus of 60 days followed by about 90 to 150 days of anestrus.
[35]: 140 The dog's visual system has evolved to aid in hunting. [28] Dogs have been shown to be able to discriminate between humans (e.g., identifying their human guardian) at a range of between 800 and 900 metres (2,600 and 3,000 ft); however, this range decreases to 500–600 metres (1,600–2,000 ft) if the object is stationary. [28]
The uterus or womb is the major female reproductive organ. The uterus provides mechanical protection, nutritional support, and waste removal for the developing embryo (weeks 1 to 8) and fetus (from week 9 until the delivery). In addition, contractions in the muscular wall of the uterus are important in pushing out the fetus at the time of birth.
In mammals, the vulva (pl.: vulvas or vulvae) comprises mostly external, visible structures of the female genitalia leading away from the interior parts of the female reproductive tract, starting at the vaginal opening. For humans, it includes the mons pubis, labia majora, labia minora, clitoris, vestibule, urinary meatus, vaginal introitus ...
The human reproductive system usually involves internal fertilization by sexual intercourse. During this process, the male inserts their erect penis into the female 's vagina and ejaculates semen, which contains sperm. The sperm then travels through the vagina and cervix into the uterus or fallopian tubes for fertilization of the ovum.
Polygyny in animals. Polygyny (/ pəˈlɪdʒɪni /; from Neo-Greek πολυγυνία, from πολύ- (polú-) 'many' and γυνή (gunḗ) 'woman, wife') [1] is a mating system in which one male lives and mates with multiple females but each female only mates with a few males. Systems where several females mate with several males are defined ...
The vulval vestibule (also known as the vulvar vestibule or vestibule of vagina) is the part of the vulva between the labia minora. At the innermost part are the vaginal introitus and urinary meatus. The Bartholin's and Skene's glands each have two openings to the vestibule on the inside. The outer edge, marked by a coloration difference in the ...