The stage of animal development in the uterus before the point at which the animal is considered a fetus. In humans this is equivalent to the first three months.
A set of trumpet-like tubes that carries a fertilized egg from the ovary to the uterus.
The process of cellular fusion that takes place in sexual reproduction. The nucleus of a male reproductive cell, or gamete, fuses with the nucleus of a female gamete to produce a zygote.
An unborn or unhatched vertebrate that has taken on the shape typical of its kind. An unborn human usually is called a fetus during the period from three months after fertilization to the time of birth.
The time between fertilization and birth, during which the unborn offspring develops in the uterus.
Molecules produced by living cells, which send signals to spots remote from their point of origin and induce specific effects on the activities of other cells.
Female reproductive organ that contains the eggs.
A term for an animal that gives birth to eggs that must develop before hatching. Compare with viviparous.
A term for an animal that produces eggs but retains them inside the body until hatching occurs, so that "live" offspring are born. Compare with oviparous and viviparous.
An egg cell.
A reproductive organ, found in most female mammals, in which an embryo and, later, a fetus grows and develops.
A passage from the uterus to the outside of the body.
A term for an animal that gives birth to live offspring. Compare with oviparous.