Key Terms
- asexual reproduction
- a mechanism that produces offspring that are genetically identical to the parent
- blastocyst
- the structure formed when cells in the mammalian blastula separate into an inner and outer layer
- budding
- a form of asexual reproduction that results from the outgrowth of a part of an organism leading to a separation from the original animal into two individuals
- bulbourethral gland
- the paired glands in the human male that produce a secretion that cleanses the urethra prior to ejaculation
- clitoris
- a sensory and erectile structure in female mammals, homologous to the male penis, stimulated during sexual arousal
- corpus luteum
- the endocrine tissue that develops from an ovarian follicle after ovulation; secretes progesterone and estrogen during pregnancy
- estrogen
- a reproductive hormone, usually present in animals of any sex, which in females assists in endometrial regrowth, ovulation, and calcium absorption
- external fertilization
- the fertilization of eggs by sperm outside an animal’s body, often during spawning
- fission
- (also, binary fission) a form of asexual reproduction in which an organism splits into two separate organisms or two parts that regenerate the missing portions of the body
- follicle stimulating hormone (FSH)
- a reproductive hormone that causes sperm production in males and follicle development in females
- fragmentation
- the breaking of an organism into parts and the growth of a separate individual from each part
- gastrulation
- the process in which the blastula folds over itself to form the three germ layers
- gestation
- the development before birth of a viviparous animal
- gestation period
- the length of time of development, from conception to birth, of the young of a viviparous animal
- gonadotropin-releasing hormone (GnRH)
- a hormone from the hypothalamus that causes the release of FSH and LH from the anterior pituitary
- hermaphroditism
- the state of having both male and female reproductive structures within the same individual
- human beta chorionic gonadotropin (β-HCG)
- a hormone produced by the chorion of the zygote that helps to maintain the corpus luteum and elevated levels of progesterone
- in vitro
- taking place in a test tube, culture dish, or elsewhere outside a living organism
- inhibin
- a hormone made by Sertoli cells, provides negative feedback to hypothalamus in control of FSH and GnRH release
- inner cell mass
- the inner layer of cells in the blastocyst, which becomes the embryo
- internal fertilization
- the fertilization of eggs by sperm inside the body of the female
- interstitial cell of Leydig
- a cell type found next to the seminiferous tubules that makes testosterone
- labia majora
- the large folds of tissue covering inguinal area
- labia minora
- the smaller folds of tissue within labia majora
- luteinizing hormone (LH)
- a reproductive hormone that causes testosterone production in males and ovulation and lactation in females
- menstrual cycle
- the cycle of the degradation and re-growth of the endometrium
- oogenesis
- the process of producing haploid eggs
- organogenesis
- the process of organ formation during development
- ovarian cycle
- the cycle of preparation of egg for ovulation and the conversion of the follicle to the corpus luteum
- oviduct
- (also, fallopian tube) the muscular tube connecting uterus with ovary area
- oviparity
- a process by which fertilized eggs are laid outside the female’s body and develop there, receiving nourishment from the yolk that is a part of the egg
- ovoviparity
- a process by which fertilized eggs are retained within the female; the embryo obtains its nourishment from the egg’s yolk, and the young are fully developed when they are hatched
- ovulation
- the release of an oocyte from a mature follicle in the ovary of a vertebrate
- parthenogenesis
- a form of asexual reproduction in which an egg develops into a complete individual without being fertilized
- penis
- the male reproductive structure for urine elimination and copulation
- placenta
- the organ that supports the transport of nutrients and waste between the mothers and fetus’ blood in eutherian mammals
- progesterone
- a reproductive hormone in usually present in animals of any sex; in human females it assists in endometrial regrowth and inhibition of FSH and LH release
- prostate gland
- a structure that is a mixture of smooth muscle and glandular material and that contributes to semen
- scrotum
- a sac containing testes, exterior to body
- semen
- a fluid mixture of sperm and supporting materials
- seminal vesicle
- a secretory accessory gland in male; contributes to semen
- seminiferous tubule
- the structures within which sperm production occurs in the testes
- Sertoli cell
- a cell in the walls of the seminiferous tubules that assists developing sperm and secretes inhibin
- sex determination
- the mechanism by which the sex of individuals in sexually reproducing organisms is initially established
- sexual reproduction
- a form of reproduction in which cells containing genetic material from two individuals combines to produce genetically unique offspring
- spermatogenesis
- the process of producing haploid sperm
- testes
- a pair of male reproductive organs
- testosterone
- a reproductive hormone usually present in animals of any sex, and that assists in sperm production and promoting secondary sexual characteristics
- trophoblast
- the outer layer of cells in the blastocyst, which gives rise to the embryo’s contribution to the placenta
- uterus
- a female reproductive structure in which an embryo develops
- vagina
- a muscular tube for the passage of menstrual flow, copulation, and birth of offspring
- viviparity
- a process in which the young develop within the female and are born in a nonembryonic state
- zona pellucida
- the protective layer around the mammalian egg