A DNA-containing body, located in the cells of most living things, that holds most of the organism's genes.
A term for a cell that has the basic number of doubled chromosomes.
A female gamete.
The stage of animal development in the uterus before 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.
Fixed-action patterns of behavior, or strong responses on the part of ananimal to particular stimuli. FAP is virtually synonymous with instinct.
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 an 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.
A reproductive cell—that is, a mature male or female germ cell that possesses a haploid set of chromosomes and is prepared to form a new diploid by undergoing fusion with a haploid gamete of the opposite sex. Sperm and egg cells are, respectively, male and female gametes.
The sex organs, which include the male penis and the female vagina.
The period between fertilization and birth during which the unborn offspring develops in the uterus.
A term for a cell that has half the number of chromosomes that appear in a diploid or somatic cell.
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.
Sloughing off of the lining of the uterus, which occurs monthly in non pregnant females who have not reached menopause (the point at which menstrual cycles cease) and which is manifested as a discharge of blood.
Female reproductive organ that contains the eggs.
An egg cell.
A stage in the maturation of humans and higher primates where in the person first becomes capable of sexual reproduction. It is marked by the development of secondary sex characteristics, the maturation of the genital organs, and the beginning of menstruation in females. Puberty typically takes place somewhere between the ages of about 10 and 14 years.
Those unique traits that mark an individual as a male or female but which are not manifested in the sexual organs themselves. Facial hair and a deep voice in males or breast development as well as hip and buttocks development in females areexamples.
One of the two major varieties of reproduction, along with asexual reproduction. In contrast to asexual reproduction, which involves a single organism, sexual reproduction involves two. Sexual reproduction occurs when male and female gametes undergo fusion, a process known as fertilization, and produce cells that are genetically different from those of eitherparent.
A male gamete.
The pair of male reproductive glands located in the scrotum, a skin-covered sac that hangs from the groin.
A reproductive organ, found in most female mammals, in which an embryo and later a fetus grow and develop.
A passage from the uterus to the outside of the body.
A diploid cell formed by the fusion of two gametes.