Form of reproduction in which offspring arise from only one parent
The combination of genetic material from two individuals to create a third individual
A sex cell; sperm or egg cell
Male gamete
Female gamete
The union of two gametes
Fused egg and sperm; develops into a diploid individual
Release of gametes by males and females into the same environment; fertilization occurs outside the body
Use of a copulatory organ to deposit sperm inside a female’s body
Process by which cells acquire specialized functions
Developmental process that establishes the body’s overall shape and structure
Development of a juvenile animal into an adult while passing through intervening larval stages
Developmental process in which an animal changes drastically in body form during the transition between juvenile and adult
Immature stage of animal development; does not resemble the adult of the species
Development pattern in which a juvenile animal resembles an adult
Organ system consisting of organs that produce and transport gametes and that may nurture developing offspring
Gland that manufactures hormones and gametes in animals; ovary or testis
Specialized cell that gives rise to gametes
Trait that distinguishes the sexes but does not participate directly in reproduction
Male gonad; organ that produces sperm and hormones
The sac containing the testes
tube that receives and stores sperm from one testis
Tube that transports sperm from an epididymis to an ejaculatory duct
Tube that deposits sperm into the urethra
Tube that transports urine (and semen in males) out of the body
Cylindrical male organ of copulation and urination
Fluid that carries sperm cells out of the body
structure that contributes fluid, fructose, and prostaglandins to semen
Male structure between the bladder and the penis; produces a milky, alkaline fluid that activates sperm
Small, mucus-secreting gland near the male urethra
Pleasurable sensation, accompanied by involuntary muscle contractions, associated with sexual activity
Discharge of semen through the penis
The production of sperm
Tubule within a testis where sperm form and mature
Cell that supports developing sperm cells within a seminiferous tubule
Testosterone-secreting endocrine cell in a testis
Diploid germ cell in the wall of a seminiferous tubule; divides mitotically to yield a stem cell and a primary spermatocyte
Diploid cell arising from a spermatogonium; undergoes meiosis I and yields two haploid secondary spermatocytes
Haploid cell that undergoes meiosis II and yields two haploid spermatids
One of four haploid cells produced in meiosis II of spermatogenesis
Mature sperm cell
Structure covering the head of a sperm cell, containing enzymes that enable the sperm to penetrate layers around the oocyte
Reproductive hormone produced in the hypothalamus in both sexes; stimulates the release of FSH and LH from the anterior pituitary
Hormone produced in the anterior pituitary; stimulates secretion of sex hormones in both sexes
Reproductive hormone produced in the anterior pituitary; stimulates secretion of sex hormones in both sexes
Steroid sex hormone produced primarily in the testes of male vertebrates
Nourishing cell surrounding an oocyte
Tube that conducts an oocyte from an ovary to the uterus
Muscular, saclike organ where embryo and fetus develop
Inner uterine lining that is shed during menstruation and supports an embryo during pregnancy
Discharge of the endometrium through the vagina during a menstrual period
Conduit from the uterus to the outside of the body; receives the penis during intercourse; the birth canal
Small, highly sensitive female sexual organ at the junction of the labia
Milk-producing organ in female mammals
External female genitalia; the labia, clitoris, and vaginal opening
The production of egg cells
Diploid germ cell in an ovary; divides mitotically to yield two primary oocytes
Diploid cell arising from an oogonium; undergoes meiosis I and yields a haploid polar body and a haploid secondary oocyte
Haploid cell that undergoes meiosis II and yields a haploid polar body and a haploid egg cell
Small, haploid byproduct of female meiosis; typically cannot be fertilized
Release of an oocyte from an ovarian follicle
Gland formed from a ruptured ovarian follicle that has recently released an oocyte
Hormonal cycle that controls the timing of oocyte maturation in the ovaries
Hormonal cycle that prepares the uterus for pregnancy
Steroid sex hormone produced in ovaries of female vertebrates
Steroid sex hormone produced in ovaries of female vertebrates
Use of devices or practices that prevent pregnancy
Infection caused by a virus, bacterium, protist, or fungus that spreads during sexual contact
First 2 weeks of human development
Period of rapid cell division following fertilization
Preembryonic stage consisting of a solid ball of cells
Preembryonic stage consisting of a fluid-filled ball of cells; develops into the embryo and part of the placenta
Cells in the blastocyst that develop into the embryo
Embedding of the blastocyst into the uterine lining
Hormone secreted by the trophoblast and the placenta; indirectly prevents menstruation
In the preembryo, a flattened, two-layered mass of cells that develops into the embryo
Outermost germ layer in an animal embryo; develops into skin and nervous system
Innermost germ layer in an animal embryo; develops into lining of digestive tract and other internal organs
Embryonic germ layer between ectoderm and endoderm in an animal embryo; develops into muscles, bones, the circulatory system, and several other structures
Early animal embryo consisting of two (cnidarians) or three (other animals) tissue layers
Stage of human development lasting from the end of the second week until the end of the eighth week of gestation
Extraembryonic membrane that manufactures blood cells and gives rise to the umbilical cord’s blood vessels
Extraembryonic membrane that forms beneath the embryonic disc and manufactures blood cells that support an early embryo
Protective extraembryonic membrane that contains amniotic fluid surrounding an embryo or fetus
Outermost extraembryonic membrane; helps establish the placenta
Fingerlike projection extending from the chorion to the uterine lining; site of exchange between a woman’s blood and a fetus
Structure that connects the developing fetus to the maternal circulation in placental mammals
Ropelike structure containing blood vessels that connect an embryo or fetus with the placenta
Furrow along the back of the embryonic disc in the third week of human development; longitudinal axis around which later structures develop
Flexible rod extending along a chordate’s back; one of the four characteristics of chordates
Embryonic precursor of the central nervous system
Stage of human development lasting from the beginning of the ninth week of gestation through birth
Abnormality that causes death or disability in a newborn