Chapter 10
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sexually dimorphic behavior
A behavior that has different forms or that occurs with different probabilities or under different circumstances in males and females.
gamete
A mature reproductive cell; a sperm or ovum.
sex chromosome
The X and Y chromosomes, which determine an organism's gender. Normally, XX individuals are female, and XY individuals are male.
gonad
An ovary or testis.
organizational effect
The effect of a hormone on tissue differentiation and development.
activational effect
The effect of a hormone that occurs in the fully developed organism; may depend on the organism's prior exposure to the organizational effects of hormones.
Müllerian system/Mullerian system
The embryonic precursors of the female internal sex organs.
Wolffian system
The embryonic precursors of the male internal sex organs.
anti-Müllerian hormone/anti-Mullerian hormone
A peptide secreted by the fetal testes that inhibits the development of the Müllerian system, which would otherwise become the female internal sex organs.
defeminizing effect
An effect of a hormone present early in development that reduces or prevents the later development of anatomical or behavioral characteristics typical of females.
androgen
A male sex steroid hormone. Testosterone is the principal mammalian androgen.
masculinizing effect
An effect of a hormone present early in development that promotes the later development of anatomical or behavioral characteristics typical of males.
testosterone
The principal androgen found in males.
dihydrotestosterone
An androgen, produced from testosterone through the action of the enzyme 5à" reductase.
androgen insensitivity syndrome
A condition caused by a congenital lack of functioning androgen receptors; in a person with XY sex chromosomes, causes the development of a female with testes but no internal sex organs.
persistent Müllerian duct syndrome/persistent Mullerian duct syndrome
A condition caused by a congenital lack of functioning anti-Müllerian hormone receptors; in a male, causes development of both male and female internal sex organs.
Turner's syndrome
The presence of only one sex chromosome (an X chromosome); characterized by lack of ovaries but otherwise normal female sex organs and genitalia.
gonadotropin releasing hormone
A hypothalamic hormone that stimulates the anterior pituitary gland to secrete gonadotropic hormone.
gonadotropic hormone
A hormone of the anterior pituitary gland that has a stimulating effect on cells of the gonads.
follicle-stimulating hormone/FSH
The hormone of the anterior pituitary gland that causes development of an ovarian follicle and the maturation of its oocyte into an ovum.
luteinizing hormone/LH
A hormone of the anterior pituitary gland that causes ovulation and development of the ovarian follicle into a corpus luteum.
estradiol
The principal estrogen of many mammals, including humans.
estrogen
A class of sex hormones that cause maturation of the female genitalia, growth of breast tissue, and development of other physical features characteristic of females.
menstrual cycle
The female reproductive cycle of most primates, including humans; characterized by growth of the lining of the uterus, ovulation, development of a corpus luteum, and (if pregnancy does not occur), menstruation.
estrous cycle
The female reproductive cycle of mammals other than primates.
ovarian follicle
A cluster of epithelial cells surrounding an oocyte, which develops into an ovum.
corpus luteum
A cluster of cells that develops from the ovarian follicle after ovulation; secretes estradiol and progesterone.
progesterone
A steroid hormone produced by the ovary that maintains the endometrial lining of the uterus during the later part of the menstrual cycle and during pregnancy; along with estradiol, it promotes receptivity in female mammals with estrous cycles.
refractory period
A period of time after a particular action (for example, an ejaculation by a male) during which that action cannot occur again.
Coolidge effect
The restorative effect of introducing a new female sex partner to a male that has apparently become "exhausted" by sexual activity.
aromatization
A chemical reaction catalyzed by an aromatase; the process by which testosterone is transformed into estradiol.
oxytocin
A hormone secreted by the posterior pituitary gland; causes contraction of the smooth muscle of the milk ducts, the uterus, and the male ejaculatory system; also serves as a neurotransmitter in the brain.
prolactin
A hormone of the anterior pituitary gland, necessary for production of milk; has an inhibitory effect on male sexual behavior.
lordosis
A spinal sexual reflex seen in many four-legged female mammals; arching of the back in response to approach of a male or to touching the flanks, which elevates the hindquarters.
pheromone
A chemical released by one animal that affects the behavior or physiology of another animal; usually smelled or tasted.
Lee-Boot effect
The increased incidence of false pregnancies seen in female animals that are housed together; caused by a pheromone in the animals' urine; first observed in mice.
Whitten effect
The synchronization of the menstrual or estrous cycles of a group of females, which occurs only in the presence of a pheromone in a male's urine.
Vandenbergh effect
The earlier onset of puberty seen in female animals that are housed with males; caused by a pheromone in the male's urine; first observed in mice.
Bruce effect
Termination of pregnancy caused by the odor of a pheromone in the urine of a male other than the one that impregnated the female; first identified in mice.
vomeronasal organ
A sensory organ that detects the presence of certain chemicals, especially when a liquid is actively sniffed; mediates the effects of some pheromones.
accessory olfactory bulb
A neural structure located in the main olfactory bulb that receives information from the vomeronasal organ.
medial nucleus of the amygdala
A nucleus that receives olfactory information from the olfactory bulb and accessory olfactory bulb; involved in the effects of odors and pheromones on reproductive behavior.
congenital adrenal hyperplasia/CAH
A condition characterized by hypersecretion of androgens by the adrenal cortex; in females, causes masculinization of the external genitalia.
spinal nucleus of the bulbocavernosus/SNB
A nucleus located in the lower spinal cord; in some species of rodents, present only in males.
medial preoptic area/MPA
An area of cell bodies just rostral to the hypothalamus; plays an essential role in male sexual behavior.
sexually dimorphic nucleus
A nucleus in the preoptic area that is much larger in males than in females; first observed in rats; plays a role in male sexual behavior.
vasopressin
A hormone secreted by the posterior pituitary gland that controls the secretion of urine by the kidneys; also serves as a neurotransmitter in the brain.
ventromedial nucleus of the hypothalamus/VMH
A large nucleus of the hypothalamus located near the walls of the third ventricle; plays an essential role in female sexual behavior.
periaqueductal gray matter/PAG
The region of the midbrain that surrounds the cerebral aqueduct; plays an essential role in various species-typical behaviors, including female sexual behavior.
parturition
The act of giving birth.
stria terminalis
A long fiber bundle that connects portions of the amygdala with the hypothalamus.
ventral tegmental area
A nucleus in the ventral midbrain; plays an essential role in maternal behavior.