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Animal Reproduction

sexual reproduction

process in which genetic material from two parents combines and produces offspring that differ genetically from either parent

2 modes of animal reproduction

sexual and asexual


diploid cell formed when the nucleus of a haploid sperm cell fuses with the nucleus of a haploid egg cell

asexual reproduction

reproduction that does not involve the union of gametes and in which a single parent produces offspring that are genetically identical to the parent


form of asexual reproduction in which an organism splits into two, and each half grows new parts to become a complete organism


asexual reproduction in which a part of the parent organism pinches off and forms a new organism


process in which an unfertilized egg develops into a new individual (bees, ants)


process in which an egg is released from the ovary


existance of reproductive organs of both sexes in the same individual


process in sexual reproduction in which male and female reproductive cells join to form a new cell

external fertilization

the process by which the female lays eggs and the male fertilizes them once they are outside of the female

internal fertilization

the process by which the male places the sperm inside the females's body, where the eggs are fertilized


organs that produce gametes


sac in female reproductive system that holds sperm for extended periods


A common opening for the digestive, urinary, and reproductive tracts found in many nonmammalian vertebrates but in few mammals.


cluster of cells that surround, protect, and nourish a developing egg cell in an ovary


a female gametocyte that develops into an ovum after two meiotic divisions

corpus luteum

ovarian structure that forms from a follicle after ovulation; secretes progesterone and estrogen


either of a pair of fallopian tubes conducting the egg from the ovary to the uterus


organ of the female reproductive system in which a fertilized egg can develop


Inner, mucous membrane lining of the uterus, rich with blood vessels


necklike opening to the uterus


in the human female reproductive system, a canal that leads from the uterus to the outside of the body


external female genitalia; includes the labia, hymen, clitoris, and the vaginal orifice

labia majora

two large folds of fatty tissue that are covered with hair on their outer surfaces; they enclose and protect the vagina

labia minora

Two smaller hairless folds of tissue that are located within the labia majora


a fold of tissue that partly covers the entrance to the vagina of a virgin


organ of sensitive erectile tissue anterior to the opening of the female urethra


head of the penis or clitoris



mammary glands

specialized organs in mammals that produce milk to nourish the young


The male gonads, which produce sperm and secrete male sex hormones.

semininferous tubules

specialized coils of tiny tubules responsible for production of sperm, located in the testes

Leydig cells

A cell that produces testosterone and other androgens and is located between the seminiferous tubules of the testes.


the external pouch that contains the testes


structure in the male reproductive system in which sperm fully mature and are stored


ejection of sperm and fluid from the male urethra

vas deferens

a duct that carries spermatozoa from the epididymis to the ejaculatory duct

ejaculatory duct

a part of the seminal duct formed by the duct from the seminal vesicle and the vas deferens


tube that carries urine from the bladder and releases it from the body; in males, tube through which semen is released from the body


the thick white fluid containing spermatozoa that is ejaculated by the male genital tract

seminal vesicles

produce about 60% of seminal fluid, these are located at the posterior wall of the urinary bladder close to the terminus of the ductus deferens. They produce a substance that nourishes the sperm passing through the tract or that promote the fertilizing capabiltiy of sperm in some way

prostate glands

secretes products directly into urethra through small ducts. contains anticoagulant enzymes and citrate.


the development and maturation of sex cells through meiosis


produces 4 functional spermatozoa


the production, growth, and maturation of an egg, or ovum

menstrual cycle

the female reproductive cycle, characterized by a monthly change of the lining of the uterus and the discharge of blood

ovarian cycle

cyclic changes that occur in the ovaries

Luteal phase

phase of the menstrual cycle characterized by the formation of the corpus luteum following ovulation

proliferative phase

Phase of reproductive cycle during which the uterine wall begins to thicken, The second phase of the uterine (endometrial) cycle, during which the endometrium (shed off during menstration is rebuilt). This phase of the cycle is under the control of estrogen, secreted from the follicle developing in the ovary during this time period. The proliferative phase typically lasts from day 6 to day 14 of the menstrual cycle.

Secretory phase

The third phase of the uterin (endometrial) cycle, during which the rebuilt endometrium is enhanced with glycogen and lipid stores. The secretory phase is primarily under the controll of progestone and estrogen (secreted from the copus luteum during this time period), adn typically lasts from day 15 to day 28 of the menstrual cycle.

menstrual flow phase

The portion of the uterine cycle when menstrual bleeding occurs


the time of natural cessation of menstruation; also refers to the biological changes a woman experiences as her ability to reproduce declines.

estrous cycle

A reproductive cycle characteristic of female mammals except higher primates, in which the nonpregnant endometrium is reabsorbed rather than shed, and sexual response occurs only during mid-cycle at estrus.


In the sexual response cycle, engorgement of the blood vessels, particularly in the genital area, due to increased blood flow


delayed relaxation of a muscle after contraction


sexual intercourse; copulation


the repeated division of a fertilised ovum


A fluid-filled sphere formed about 5 days after fertilization of an ovum that is made up of an outer ring of cells and inner cell mass. THis is the structure that implants in the endometrium of the uterus.


period from fertilization of the ovum to birth


outer cells of the blastocyst that secrete enzymes that allow implantation


the vascular structure in the uterus of most mammals providing oxygen and nutrients for and transferring wastes from the developing fetus


process of organ formation that takes place during the first two months of prenatal development


the developing human organism from 9 weeks after conception to birth


the production and secretion of milk by the mammary glands

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