Reproduction in mammals

thumb|Identical twins can be difficult to visually distinguish especially when young, as demonstrated by brothers Billy and Bobby Mauch. Twins are two offspring produced by the same pregnancy. Twins can be either monozygotic ('identical'), meaning that they develop from one zygote, which splits and forms two embryos, or dizygotic ('non-identical' or 'fraternal'), meaning that each twin develops from a separate egg and each egg is fertilized by its own sperm cell. Since identical twins develop from one zygote, they will share the same sex, while fraternal twins may or may not. In very rare cas

pregnancy through in vivo fertilization

Lactation describes the secretion of milk from the mammary glands in addition to the period of time that a parent lactates to feed her young. The process can occur with all sexually mature female mammals, although it may predate mammals. The process of feeding milk in all female creatures is called nursing, and in humans it is also called breastfeeding. Newborn infants often produce some milk from their own breast tissue, known colloquially as witch's milk.

type of ovulation cycle

alt=Drawing of a sagittal cross-section of a fetus in the pregnant parent's amniotic cavity.|thumb|upright|Drawing of a fetus in utero. Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregnancy can have one or more gestations at the same time, for example in a multiple birth.

thumb|320px|Baculum of a dog's penis; the arrow shows the urethral sulcus, which is the groove in which the urethra lies. thumb|Fossil baculum of a Indarctos|bear (Indarctos) from the [[Miocene]]

mating season of ruminant mammals

Insemination is the introduction of sperm (in semen) into a female's reproductive system in order to fertilize the ovum through sexual reproduction. The sperm enters into the uterus of a mammal or the oviduct of an oviparous (egg-laying) animal. Female humans and other mammals are inseminated during sexual intercourse or copulation, but can also be inseminated by artificial insemination.

method of determining sex

gelatinous substance within the umbilical cord

Electroejaculation is a procedure used to obtain semen samples from sexually mature male mammals. The procedure is used for breeding programs and research purposes in various species, as well as in the treatment of ejaculatory dysfunction in human males. This procedure is used frequently with large mammals, particularly bulls and some domestic animals, as well as humans who have certain types of anejaculation. Electroejaculation has also been used for the cryoconservation of animal genetic resources, where semen is stored in low temperatures with the intent of conserving genetic material and f

tendency for female rodents to terminate their pregnancies following exposure to the scent of an unfamiliar male

movies for sexual arousal of pandas

ovarian follicle during folliculogenesis

gelatinous secretion used in the mating of some species

measure of viable ova

produced by females for mating

the event that a fetus is born alive with heartbeats or respiration

natural process of human ovarian cell death

Reproduction of sheep

reproduction in mammals

sexual reproduction in canine species