DEVELOPMENTS IN SEXUAL ORGANOGENESIS
L. GALLIEN*
Laboratoire d'Embryologie, Faculté des Sciences, Paris, France
I. Introduction
259
A. Genetic Foundation
259
B. Intrinsic Epigenetic Factors in Sexual Organogenesis
260
C. Extrinsic Epigene tic Factors in Sexual Organogenesis
. . . .
260
II. Epigenetic Controls during Sexual Differentiation in the Invertebrates
261
A. Sexual Differentiation in Hydras: Inter sexuality and Experimental Sex
Reversal
261
B. Endocrine Controls in Sexual Differentiation in Insects: Apical Androgenic Tissue
268
C. Endocrine Controls in Sexual Differentiation in Crustaceans: The Androgenic Gland
271
III. Epigenetic Factors in Sexual Organogenesis in Vertebrates . . . .
277
A. Lower Vertebrates: Amphibians and Fishes
277
B. Relationship between Genetic Constitution and Sexual Organogenesis . 294
C. Sexual Organogenesis in Birds
298
D. Sexual Organogenesis in Mammals
301
E. Nature of the Initial Reactions in the Differentiation of the Gonads
305
F. Summary
310
IV. General Conclusions
312
A. Role of Endocrine Factors
312
B. Relationship between Genetic Structures and Epigenetic Effects
312
C. Biosynthesis of Steroids in the Embryonic Phases of Sexual Differentiation 313
References
313
L Introduction
Sexual organogenesis is the sum total of the processes that, in the course
of development, bring about differentiation of the gonads and associated
somatic sexual characteristics to proceed in a male or a female direction.
There are varying degrees of development up to a full capacity for sexual
reproduction. Sexual organogenesis is a particular kind of morphogenesis.
Its peculiarity rests in the fact that, in its most widely developed form, that
of the gonochoric species, a morphological duality that is manifested as
sexual dimorphism results at the end of ontogenesis.
Three kinds of phenomena control sexual differentiation.
A. Genetic Foundation
The basis of the causative mechanisms is genetic. Fundamentally, each
sex is genetically bisexual, which indicates that it possesses the genes
* The author expresses his thanks for the translation of the manuscript to Florence M.
Foote, Department of Physiology, Southern Illinois University, Carbondale, Illinois.
259
L. GALLIEN*
Laboratoire d'Embryologie, Faculté des Sciences, Paris, France
I. Introduction
259
A. Genetic Foundation
259
B. Intrinsic Epigenetic Factors in Sexual Organogenesis
260
C. Extrinsic Epigene tic Factors in Sexual Organogenesis
. . . .
260
II. Epigenetic Controls during Sexual Differentiation in the Invertebrates
261
A. Sexual Differentiation in Hydras: Inter sexuality and Experimental Sex
Reversal
261
B. Endocrine Controls in Sexual Differentiation in Insects: Apical Androgenic Tissue
268
C. Endocrine Controls in Sexual Differentiation in Crustaceans: The Androgenic Gland
271
III. Epigenetic Factors in Sexual Organogenesis in Vertebrates . . . .
277
A. Lower Vertebrates: Amphibians and Fishes
277
B. Relationship between Genetic Constitution and Sexual Organogenesis . 294
C. Sexual Organogenesis in Birds
298
D. Sexual Organogenesis in Mammals
301
E. Nature of the Initial Reactions in the Differentiation of the Gonads
305
F. Summary
310
IV. General Conclusions
312
A. Role of Endocrine Factors
312
B. Relationship between Genetic Structures and Epigenetic Effects
312
C. Biosynthesis of Steroids in the Embryonic Phases of Sexual Differentiation 313
References
313
L Introduction
Sexual organogenesis is the sum total of the processes that, in the course
of development, bring about differentiation of the gonads and associated
somatic sexual characteristics to proceed in a male or a female direction.
There are varying degrees of development up to a full capacity for sexual
reproduction. Sexual organogenesis is a particular kind of morphogenesis.
Its peculiarity rests in the fact that, in its most widely developed form, that
of the gonochoric species, a morphological duality that is manifested as
sexual dimorphism results at the end of ontogenesis.
Three kinds of phenomena control sexual differentiation.
A. Genetic Foundation
The basis of the causative mechanisms is genetic. Fundamentally, each
sex is genetically bisexual, which indicates that it possesses the genes
* The author expresses his thanks for the translation of the manuscript to Florence M.
Foote, Department of Physiology, Southern Illinois University, Carbondale, Illinois.
259