Behavioral Endocrinology (Hormones & Behavior) Chapter 3

parthenogenesis

a reproductive mode whereby fertilization is not required for a female to give birth

hermaphrodites

described individuals that possess both male and female reproductive structures. It can occur either simultaneously or sequentially at different stages of the life cycle

dioecious

the characteristic of having two structurally distinct sexes (also called gonochorism)

gonads

an organ that produces gametes (i.e., the ovary and testis)

gametes

specialized cells for contributing genetic material from parents for sexual production, i.e., sperm or eggs

sex determination

the point at which an individual begins developing as either male or female. In mammals, this takes place at fertilization, depending on whether the sperm has contributed an X or a Y chromosome

phenotype

the sum of all physical characteristics of an individual that are expressed at a particular time. These traits are the result of the interplay of the genotype and the environment up to that point

genotype

the sum pf all the genetic information possessed by an individual

indifferent gonads

an early stage in development when a gonad appears structurally intermediate between a testis and an ovary

mullerian ducts

a duct system connecting the gonad to the external body wall, present in both sexes early in development, but differentiating in females into the fallopian tubes, uterus, and inner vagina

wolffian ducts

a duct system connecting the gonad to the external body wall. It is present in both sexes early in development, but in males it differentiates into the epididymis, vas deferens, and seminal vesicles

dihydrotestosterone (DHT)

metabolite of testosterone formed from testosterone by the action of the 5a-reductase enzyme; has androgenic effects on the brain, accessory sex structures and peripheral secondary sex characteristics

Turner’s syndrome

a syndrome in which externally feminine individuals possess a single X chromosome but no Y chromosome

Klinefelter’s syndrome

a syndrome in which externally masculine individuals possess two X chromosomes and a Y chromosome

testicular feminization mutation (TFM)

a genetic mutation that renders androgen receptors nonfunctional

congenital adrenal hyperplasia (CAH)

an inherited adrenal enzyme deficiency that results in the overproduction of androgens, beginning in the prenatal period and continuing until controlled with appropriate medications. The condition, if not corrected, causes stunted growth and precocious puberty in males and females. In females, the additional androgens cause various degrees of masculinization of the external genitals and the brain

ovulation

the physical release of a mature egg from the ovary

induced-ovulation

ovulation in response to stimulation by a male

hypothalamus

brain structure (group of nuclei). A neural center at the base of the diencephalic region of the brain involved in the control of rhythmic and regulatory functions, including pituitary hormone release

organizational hypothesis

the proposal that androgens secreted by the developing testes permanently masculinize the developing nervous system, resulting in an adult which will more readily display male-typical behaviors

sensitive periods

a limited time during development in which an organism can be permanently altered by a particular experience or treatment

aromatase

an enzyme that catalyzes the conversion of testosterone into estradiol

alpha-feto-protein (AFP)

a protein found in plasma that can bind to estrogens but not androgens in rodents

sexually dimorphic nucleus of the POA (SDN-POA)

a region of the preoptic area of the hypothalamus which is larger in males than in females in both rodents and humans

neurogenesis

the mitotic division of non-neuronal cells to produce neurons

spinal nucleus of the bulbocavernosus (SNB)

a group of motor neurons in the spinal cord that innervate several muscles attached t the base of the penis

corpus callosum

a fiber pathway in the brain that connects the two cerebral hemispheres