4. HORMONES AND BEHAVIOR
231
IX. Role of Hormones in the Patterning of Behavior
The discussion of the relationship between the hormones and behavior presented thus far has been focused on the action of these substances in mature animals in which the effect is one of activation, that
is the tissues mediating specific types of behavior are so affected that
the threshold for behavioral responses is lowered. Males display courtship behavior and mate, females go into estrus, etc. At earlier ages, at
least in the guinea pig and rat, gonadal hormones have an organizing
action, that is they determine the responsiveness that will later be shown
to specific hormonal substances and the nature of the response, whether
for example it be masculine or feminine (33, 33a). Experimental embryologists and endocrinologists have long been aware of this dual role
of gonadal hormones in the differentiation of the genital tracts in developing males and females and in the functioning of the tracts after the
attainment of adulthood (381-386).
Evidence that gonadal hormones
have corresponding relationships with the tissues mediating reproductive
behavior has also long existed, but it has not heretofore been considered
comparatively.
Data exist for several species of fishes, amphibians, birds, and mammals. In many cases it is known that following androgenic treatment of
young females or estrogenic treatment of young males the treated individuals take on the role of the opposite sex, but investigations of the
guinea pig and rat have been extended somewhat further. The relationships in these species will be considered first. The injection of testosterone or testosterone propionate into the amniotic cavity of 20-27 day
fetuses (32, 387-389), and the injection of pregnant guinea pigs with
testosterone propionate, have profound effects on the development of
the genital tracts and on behavior (33). Females become pseudohermaphroditic with masculinized external genitalia, hypertrophied Wolffian
ducts, frequent failure of Müllerian duct-urogenital sinus fusion, and
ovarian dysfunction. When individuals gonadectomized as adults were
tested, there was found to be a suppression of the capacity for displaying
the feminine measures of behavior (duration of heat and maximum
duration of lordosis) accompanied by a lowered responsiveness to
estradiol benzoate and progesterone, and an intensification of the masculine component (male-like mounting) accompanied by an increased
responsiveness to testosterone propionate. The results of tests at 11-12
months of age indicated that the effects are permanent. At the most the
male siblings were affected only slightly, and then only when the prenatal treatment was followed by postnatal treatment (390). Administration of the androgen between days 30 and 35 of gestation was most
231
IX. Role of Hormones in the Patterning of Behavior
The discussion of the relationship between the hormones and behavior presented thus far has been focused on the action of these substances in mature animals in which the effect is one of activation, that
is the tissues mediating specific types of behavior are so affected that
the threshold for behavioral responses is lowered. Males display courtship behavior and mate, females go into estrus, etc. At earlier ages, at
least in the guinea pig and rat, gonadal hormones have an organizing
action, that is they determine the responsiveness that will later be shown
to specific hormonal substances and the nature of the response, whether
for example it be masculine or feminine (33, 33a). Experimental embryologists and endocrinologists have long been aware of this dual role
of gonadal hormones in the differentiation of the genital tracts in developing males and females and in the functioning of the tracts after the
attainment of adulthood (381-386).
Evidence that gonadal hormones
have corresponding relationships with the tissues mediating reproductive
behavior has also long existed, but it has not heretofore been considered
comparatively.
Data exist for several species of fishes, amphibians, birds, and mammals. In many cases it is known that following androgenic treatment of
young females or estrogenic treatment of young males the treated individuals take on the role of the opposite sex, but investigations of the
guinea pig and rat have been extended somewhat further. The relationships in these species will be considered first. The injection of testosterone or testosterone propionate into the amniotic cavity of 20-27 day
fetuses (32, 387-389), and the injection of pregnant guinea pigs with
testosterone propionate, have profound effects on the development of
the genital tracts and on behavior (33). Females become pseudohermaphroditic with masculinized external genitalia, hypertrophied Wolffian
ducts, frequent failure of Müllerian duct-urogenital sinus fusion, and
ovarian dysfunction. When individuals gonadectomized as adults were
tested, there was found to be a suppression of the capacity for displaying
the feminine measures of behavior (duration of heat and maximum
duration of lordosis) accompanied by a lowered responsiveness to
estradiol benzoate and progesterone, and an intensification of the masculine component (male-like mounting) accompanied by an increased
responsiveness to testosterone propionate. The results of tests at 11-12
months of age indicated that the effects are permanent. At the most the
male siblings were affected only slightly, and then only when the prenatal treatment was followed by postnatal treatment (390). Administration of the androgen between days 30 and 35 of gestation was most