Chapter 12 Flashcards

α-fetoprotein
A protein found in the plasma of fetuses. In rodents, α-fetoprotein binds estrogens and prevents them from entering the brain.
5α-reductase
An enzyme that converts testosterone into dihydrotestosterone.
activational effect
A temporary change in behavior resulting from the administration of a hormone to an adult animal. Compare organizational effect.
allele
One of two or more different forms of a gene or genetic locus.
altricial
Referring to animals that are born in an undeveloped state and depend on maternal care, as human infants do. Compare precocial.
androgen insensitivity syndrome (AIS)
A syndrome caused by a mutation of the androgen receptor gene that renders tissues insensitive to androgenic hormones like testosterone. Affected XY individuals are phenotypic females, but they have internal testes and regressed internal genital structures. See Figure 12.16.
anti-müllerian hormone (AMH)
Also called Müllerian regression hormone (MRH). A protein hormone secreted by the fetal testis that inhibits müllerian duct development.
appetitive behavior
The second stage of mating behavior; helps establish or maintain sexual interaction. See Figure 12.1.
aromatase
An enzyme that converts many androgens into estrogens.
aromatization
The chemical reaction that converts testosterone to estradiol, and other androgens to other estrogens.
aromatization hypothesis
The hypothesis that testicular androgens enter the brain and are converted there into estrogens to masculinize the developing nervous system of some rodents.
castration
Removal of the gonads, usually the testes.
cloacal exstrophy
A rare medical condition in which XY individuals are born completely lacking a penis.
congenital adrenal hyperplasia (CAH)
Any of several genetic mutations that can result in exposure of a female fetus to adrenal androgens, which results in a clitoris that is larger than normal at birth.
Coolidge effect
The propensity of an animal that has appeared sexually satiated with a present partner to resume sexual activity when provided with a novel partner.
copulation
Also called coitus. The sexual act.
copulatory lock
Reproductive behavior in which the male’s penis swells after ejaculation so that the male and female are forced to remain joined for 5–15 minutes; occurs in dogs and some rodents, but not in humans.
dihydrotestosterone (DHT)
The 5α-reduced metabolite of testosterone; a potent androgen that is principally responsible for the masculinization of the external genitalia in mammalian sexual differentiation. See Figure 12.14.
ejaculation
The forceful expulsion of semen from the penis.
estrus
The period during which female animals are sexually receptive.
external fertilization
The process by which eggs are fertilized outside of the female’s body, as in many fishes and amphibians. Compare internal fertilization.
gamete
A sex cell (sperm or ovum) that contains only unpaired chromosomes and therefore has only half of the usual number of chromosomes.
guevedoces
Literally, “eggs at 12” (in Spanish). A nickname for individuals who are raised as girls but at puberty change appearance and begin behaving as boys.
indifferent gonads
The undifferentiated gonads of the early mammalian fetus, which will eventually develop into either testes or ovaries. See Figure 12.13. See also gonads.
internal fertilization
The process by which sperm fertilize eggs inside of the female’s body, as in all mammals, birds, and reptiles. Compare external fertilization.
intersex
Referring to an individual with atypical genital development and sexual differentiation that generally resembles a form intermediate between typical male and typical female genitals.
intromission
Insertion of the erect penis into the vagina during copulation.
lordosis
A female receptive posture in quadrupeds in which the hindquarters are raised and the tail is turned to one side, facilitating intromission by the male. See Figures 12.3, 12.6.
müllerian duct
A duct system in the embryo that will develop into female reproductive structures (fallopian tubes, uterus, and upper vagina) if testes are not present. See Figures 12.13, 12.14. Compare wolffian duct.
major histocompatibility complex (MHC)
A large family of genes that identify an individual’s tissues (to aid in immune responses against foreign proteins).
medial amygdala
A portion of the amygdala that receives olfactory and pheromonal information.
medial preoptic area (mPOA)
A region of the anterior hypothalamus implicated in the control of many behaviors, including thermoregulation, sexual behavior, and gonadotropin secretion.
medullary reticular formation
The hindmost portion of the brainstem reticular formation, implicated in motor control and copulatory behavior. See Figure 12.6.
musth
An annual period of heightened aggressiveness and sexual activity in male elephants.
neonatal
Referring to newborns.
Onuf’s nucleus
The human homolog of the spinal nucleus of the bulbocavernosus (SNB) in rats.
organizational effect
A permanent alteration of the nervous system, and thus permanent change in behavior, resulting from the action of a steroid hormone on an animal early in its development. Compare activational effect.
orgasm
The climax of sexual experience, marked by extremely pleasurable sensations.
ovulation
The production and release of an egg (ovum).
ovulatory cycle
The periodic occurrence of ovulation. See Figure 12.5.
ovum (pl. ova)
An egg, the female gamete.
pair bond
A durable and exclusive relationship between a male and a female.
parabiotic
Referring to a surgical preparation that joins two animals to share a single blood supply.
paragigantocellular nucleus (PGN)
A region of the brainstem reticular formation implicated in sleep and modulation of spinal reflexes.
parental behavior
Behavior of adult animals with the goal of enhancing the well-being of their own offspring, often at some cost to the parents.
periaqueductal gray
The neuronal body–rich region of the midbrain surrounding the cerebral aqueduct that connects the third and fourth ventricles; involved in pain perception.
phallus
The clitoris or penis.
pheromone
A chemical signal that is released outside the body of an animal and affects other members of the same species. See Figure 5.3. Compare allomone.
postcopulatory behavior
The final stage in mating behavior. Species-specific postcopulatory behaviors include rolling (in the cat) and grooming (in the rat). See Figure 12.1.
precocial
Referring to animals that are born in a relatively developed state and that are able to survive without maternal care. Compare altricial.
proceptive
Referring to a state in which an animal advertises its readiness to mate through species-typical behaviors, such as ear wiggling in the female rat.
refractory period
A period following copulation during which an individual cannot recommence copulation. The absolute refractory phase of the male sexual response is illustrated in Figure 12.9.
reticulospinal tract
A tract of axons arising from the brainstem reticular formation and descending to the spinal cord to modulate movement. Compare rubrospinal tract.
semen
A mixture of fluid, including sperm, that is released during ejaculation.
sensitive period
The period during development in which an organism can be permanently altered by a particular experience or treatment.
sex determination
The process by which the decision is made for a fetus to develop as a male or a female. In mammals this is under genetic control, but in some groups of animals, environmental variables like incubation temperature determine the sex of the offspring.
sexual attraction
The first step in the mating behavior of many animals, in which animals emit stimuli that attract members of the opposite sex. See Figure 12.1.
sexual differentiation
The process by which individuals develop either malelike or femalelike bodies and behavior.
sexual dimorphism
The condition in which males and females show pronounced sex differences in appearance.
sexually dimorphic nucleus of the preoptic area (SDN-POA)
A region of the preoptic area that is five to six times larger in volume in male rats than in females. See Figure 12.21.
sexually receptive
Referring to the state in which an individual (in mammals, typically the female) is willing to copulate. In many species, no sexual activity is possible other than during the period of sexual receptivity in the female, which generally corresponds to ovulation.
sperm
The gamete produced by males for fertilization of eggs (ova).
spinal nucleus of the bulbocavernosus (SNB)
A group of motoneurons in the spinal cord of rats that innervate striated muscles controlling the penis. See Figure 12.22. See also Onuf’s nucleus.
SRY gene
A gene on the Y chromosome that directs the developing gonads to become testes. The name SRY stands for sex-determining region on the Y chromosome.
syrinx
The vocal organ in birds.
Turner’s syndrome
A condition seen in individuals carrying a single X chromosome but no other sex chromosome.
ventromedial hypothalamus (VMH)
A hypothalamic region involved in eating and sexual behaviors. See Figures 12.6, 13.20.
vomeronasal organ (VNO)
A collection of specialized receptor cells, near to but separate from the olfactory epithelium, that detect pheromones and send electrical signals to the accessory olfactory bulb in the brain.
wolffian duct
A duct system in the embryo that will develop into male structures (the epididymis, vas deferens, and seminal vesicles) if testes are present in the embryo. See Figure 12.13. Compare müllerian duct.
zygote
The fertilized egg.
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