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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

zygote

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

Fission

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

Budding

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

parthenogenesis

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

ovulation

process in which an egg is released from the ovary

hermaphrodism

existance of reproductive organs of both sexes in the same individual

fertilization

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

gonads

organs that produce gametes

spermathecae

sac in female reproductive system that holds sperm for extended periods

cloaca

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

follicle

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

oocyte

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

oviduct

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

uterus

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

endometrium

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

cervix

necklike opening to the uterus

vagina

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

vulva

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

hymen

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

clitoris

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

glans

head of the penis or clitoris

prepuce

foreskin

mammary glands

specialized organs in mammals that produce milk to nourish the young

testes

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.

scrotum

the external pouch that contains the testes

epididymis

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

ejaculation

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

urethra

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

semen

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.

Gametogenesis

the development and maturation of sex cells through meiosis

spermogenesis

produces 4 functional spermatozoa

oogenesis

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

menopause

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.

vasocongestion

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

myotonia

delayed relaxation of a muscle after contraction

coitus

sexual intercourse; copulation

cleavage

the repeated division of a fertilised ovum

blastocyst

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.

gestation

period from fertilization of the ovum to birth

trophoblast

outer cells of the blastocyst that secrete enzymes that allow implantation

placenta

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

organogenesis

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

fetus

the developing human organism from 9 weeks after conception to birth

lactation

the production and secretion of milk by the mammary glands

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