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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.
The main male sex organs are the penis and the scrotum, which contains the testicles that produce semen and sperm, which, as part of sexual intercourse, fertilize an ovum in the female's body; the fertilized ovum develops into a fetus, which is later born as an infant. The corresponding system in females is the female reproductive system.
Anatomical terminology. [edit on Wikidata] The bulbourethral glands or Cowper's glands (named for English anatomist William Cowper) are two small exocrine and accessory glands in the reproductive system of many male mammals. [1] They are homologous to Bartholin's glands in females. The bulbourethral glands are responsible for producing a pre ...
Overall, male secondary sex characteristics include: Growth of body hair, including underarm, abdominal, chest, and pubic hair. [3][1] Growth of facial hair. [1] Enlargement of the larynx (Adam's apple) and deepening of the voice. [1][24] Increased stature; adult males are taller than adult females, on average. [1]
The prostate is the only accessory gland that occurs in male dogs. [64] Dogs can produce in one hour as much prostatic fluid as a human can in a day. They excrete this fluid along with their urine to mark their territory. [65] Additionally, dogs are the only species apart from humans seen to have a significant incidence of prostate cancer. [66]
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.
Mate choice is a major component of sexual selection, another being intrasexual selection. Ideas on sexual selection were first introduced in 1871, by Charles Darwin, then expanded on by Ronald Fisher in 1915. At present, there are five sub mechanisms that explain how mate choice has evolved over time.
Capacitation is the penultimate [1] step in the maturation of mammalian spermatozoa and is required to render them competent to fertilize an oocyte. [2] This step is a biochemical event; the sperm move normally and look mature prior to capacitation. In vivo, capacitation occurs after ejaculation, when the spermatozoa leave the vagina and enter ...