The effects of sex steroid treatments on sexual differentiation in a unisexual lizard,Cnemidophorus uniparens (Teiidae)

1986 ◽  
Vol 187 (2) ◽  
pp. 129-142 ◽  
Author(s):  
Allen J. Billy ◽  
David Crews
Keyword(s):  
Sexual Differentiation ◽  
Sex Steroid ◽  
Cnemidophorus Uniparens

Developmental deformities in the parthenogenetic lizard Cnemidophorus uniparens (Teiidae) and the "anomalous male" phenomenon

1986 ◽  
Vol 64 (11) ◽  
pp. 2418-2424 ◽  
Author(s):  
Allen J. Billy
Keyword(s):  
Sexual Differentiation ◽  
Vertebral Column ◽  
Female Offspring ◽  
Bisexual Species ◽  
Developmental Defects ◽  
Unresolved Problem ◽  
Parthenogenetic Species ◽  
Parthenogenetic Female ◽  
Lower Jaw ◽  
Cnemidophorus Uniparens

Parthenogenetic species of lizard occasionally produce male progeny characterized by developmental defects and low viability. Production of anomalous males is an unresolved problem in sexual differentiation as parthenogenetic female lizards are expected to produce female offspring. The "anomalous male" phenomenon was examined by sexing nonviable embryos produced by the parthenogenetic whiptail lizard Cnemidophorus uniparens. Twenty-six deformed embryos were obtained; all were female except for three which did not possess gonads. Male embryos were not detected. Developmental deformities found in Cnemidophorus embryos included anophthalmia, micropthalmia, encephalocoele, hypoplasia of the lower jaw, head foreshortening, gastroschisis, and malformations of the vertebral column. Several embryos possessed a combination of defects. Four hypotheses are presented to account for production of anomalous males by reptilian parthenoforms. Three hypotheses involve production of sex-reversed males (genetic females). A fourth hypothesis asserts that anomalous males are derived from hybridization events between a female from a unisexual species and a male from a bisexual species. Of the four hypotheses, the hybridization hypothesis has the greatest utility in explaining production of anomalous males by parthenogenetic lizards.

Sexual differentiation of the urogenital tract in the chicken embryo: autoradiographic localization of sex-steroid target cells during development

Development ◽  
1981 ◽  
Vol 63 (1) ◽  
pp. 207-223
Author(s):  
Jean-Marie Gasc ◽  
Walter E. Stumpf
Keyword(s):  
Sexual Differentiation ◽  
Reproductive Tract ◽  
Sex Steroid ◽  
Target Cells ◽  
Steroid Dependent ◽  
Receptor Sites ◽  
Topographical Distribution ◽  
Nuclear Labelling ◽  
Different Types ◽  
Autoradiographic Technique

The determinant role ascribed to steroid hormones in sexual differentiation of the reproductive tract of the embryo implies the presence of target cells for sex steroids. An autoradiographic technique adapted for diffusible compounds was employed to characterize and localize cells which concentrate either [3H]oestradiol (E2) or [3H]dihydrotestosterone (DHT) in their nuclei. This paper describes the topographical distribution of cells containing receptor sites for oestrogen or androgen in various tissues of the reproductive tract of chicken embryos from day 6 to 15 of incubation. Receptor sites for oestradiol are present in the mesenchyme of the cloaca and in urodeum and vascular body. In the lower part of the Wolffian duct, only epithelial cells display nuclear labelling. In the Müllerian duct, nuclear receptor sites for [3H]oestradiol are observed not before day 15. Receptor sites for DHT are localized in the mesenchyme of the cloacal region from day 7 to 15. The Wolffian, but not the Müllerian duct contains receptor sites for DHT in the nuclei of epithelial and mesenchymal cells. Cross-competition experiments between [3H]E2 or [3H]DHT and unlabelled DHT or E2 respectively, show that 2 different types of receptor sites exist. The observations indicate: (a) complementary roles for oestrogenic and androgenic hormones in embryonic sexual differentiation; (b) precocity of receptors for sex hormones during embryonic development; (c) importance of mesenchyme in differentiation processes which are sex-steroid dependent.

Prenatal inhibition of hypothalamic sex steroid uptake by cocaine: effects on neurobehavioral sexual differentiation in male rats

1990 ◽  
Vol 53 (2) ◽  
pp. 230-236 ◽  
Author(s):  
William J. Raum ◽  
Robert F. McGivern ◽  
Margaret A. Peterson ◽  
James H. Shryne ◽  
Roger A. Gorski
Keyword(s):  
Sexual Differentiation ◽  
Male Rats ◽  
Sex Steroid

Putative aromatase inhibitor induces male sex determination in a female unisexual lizard and in a turtle with temperature-dependent sex determination

1994 ◽  
Vol 141 (2) ◽  
pp. 295-299 ◽  
Author(s):  
T Wibbels ◽  
D Crews
Keyword(s):  
Sex Determination ◽  
Aromatase Inhibitor ◽  
Sexual Differentiation ◽  
Trachemys Scripta ◽  
Aromatase Activity ◽  
Temperature Dependent ◽  
Endogenous Production ◽  
Diverse Species ◽  
Male Sex ◽  
Cnemidophorus Uniparens

Abstract Treatment of developing embryos of two diverse species of reptiles with fadrozole (a potent and specific nonsteroidal inhibitor of aromatase activity in mammals) resulted in the induction of male sex determination. In the first experiment, males were produced in an all-female parthenogenic species of lizard (Cnemidophorus uniparens). In the second experiment, male sex determination was induced in a turtle (Trachemys scripta) with temperature-dependent sex determination. The results support the hypothesis that the endogenous production of oestrogen may represent a pivotal step in the sex determination cascade of reptiles. Further, the production of male C uniparens indicates that the genes required for male sexual differentiation have not been lost in this parthenogenic lizard. Journal of Endocrinology (1994) 141, 295–299

scholarly journals Sex steroid dynamics during embryogenesis and sexual differentiation in Eurasian perch, Perca fluviatilis

2007 ◽  
Vol 67 (5) ◽  
pp. 1046-1052 ◽  
Author(s):  
C. Rougeot ◽  
A. Krim ◽  
S.N.M. Mandiki ◽  
P. Kestemont ◽  
C. Mélard
Keyword(s):  
Sexual Differentiation ◽  
Perca Fluviatilis ◽  
Sex Steroid ◽  
Eurasian Perch ◽  
Perch Perca Fluviatilis

Androgen-induced plasticity at a “vocal” neuromuscular synapse

1994 ◽  
Vol 52 ◽  
pp. 32-33
Author(s):  
Darcy B. Kelley ◽  
Martha L. Tobias ◽  
Mark Ellisman
Keyword(s):  
Xenopus Laevis ◽  
Motor Neurons ◽  
Sexual Differentiation ◽  
Molecular Basis ◽  
Neuromuscular Synapse ◽  
Sexually Dimorphic ◽  
Intracellular Protein ◽  
Developmental Program ◽  
Androgen Action ◽  
Clawed Frog

Brain and muscle are sexually differentiated tissues in which masculinization is controlled by the secretion of androgens from the testes. Sensitivity to androgen is conferred by the expression of an intracellular protein, the androgen receptor. A central problem of sexual differentiation is thus to understand the cellular and molecular basis of androgen action. We do not understand how hormone occupancy of a receptor translates into an alteration in the developmental program of the target cell. Our studies on sexual differentiation of brain and muscle in Xenopus laevis are designed to explore the molecular basis of androgen induced sexual differentiation by examining how this hormone controls the masculinization of brain and muscle targets.Our approach to this problem has focused on a highly androgen sensitive, sexually dimorphic neuromuscular system: laryngeal muscles and motor neurons of the clawed frog, Xenopus laevis. We have been studying sex differences at a synapse, the laryngeal neuromuscular junction, which mediates sexually dimorphic vocal behavior in Xenopus laevis frogs.

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