Ontogeny of the Sexually Dimorphic Sonic Muscle in Three Sciaenid Species

Gary L. Hill; Michael L. Fine; John A. Musick

doi:10.2307/1445663

Functional morphology of toadfish sonic muscle fibers: relationship to possible fiber division

Canadian Journal of Zoology ◽

10.1139/z93-318 ◽

1993 ◽

Vol 71 (11) ◽

pp. 2262-2274 ◽

Cited By ~ 30

Author(s):

Michael L. Fine ◽

Barbara Bernard ◽

Thomas M. Harris

Keyword(s):

Energy Efficient ◽

Sound Production ◽

Muscle Fibers ◽

Sexually Dimorphic ◽

Small Energy ◽

Opsanus Tau ◽

Sonic Muscle ◽

Oyster Toadfish ◽

Fiber Fragmentation ◽

Rapid Contraction

Sexually dimorphic sonic muscles, which vibrate the swimbladder for sound production in the oyster toadfish (Opsanus tau), are among the fastest vertebrate muscles. Previous work has shown that sonic muscle fibers are smaller in males, have an unusual morphology, and increase in number and size for life. We now report evidence consistent with the hypothesis that mature, presumably postmitotic, sonic fibers divide, and suggest that division, which returns fibers to small energy-efficient units, is necessary because mitochondria are excluded from the fiber's contractile cylinder. Large fibers, potential candidates for division, develop fragments of contractile cylinder separated by channels of an expanded sarcoplasmic reticulum; these channels can assume the appearance of the sarcoplasm (glycogen granules and mitochondria) beneath the sarcolemma. Measurements indicate that contractile cylinder diameter does not increase with fish size and that diameters are approximately 21% larger in females (p < 0.0001). Fiber fragmentation, possible division, and the presence of smaller fibers with smaller diameter contractile cylinders in males are seen as adaptations for repeated rapid contraction and fatigue resistance during production of the male's courtship boatwhistle call.

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Androgen-induced plasticity at a “vocal” neuromuscular synapse

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100167895 ◽

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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The Relationship of Digit Ratio (2D:4D) and Gender-Role Orientation in Four National Samples

Journal of Individual Differences ◽

10.1027/1614-0001.28.2.78 ◽

2007 ◽

Vol 28 (2) ◽

pp. 78-87 ◽

Cited By ~ 12

Author(s):

Stefan J. Troche ◽

Nina Weber ◽

Karina Hennigs ◽

Carl-René Andresen ◽

Thomas H. Rammsayer

Keyword(s):

Gender Role ◽

Sex Role ◽

Role Orientation ◽

Sexually Dimorphic ◽

Gender Role Orientation ◽

Left Hand ◽

Fourth Finger ◽

And Gender ◽

Relationship Of ◽

The Relationship

Abstract. The ratio of second to fourth finger length (2D:4D ratio) is sexually dimorphic with women having higher 2D:4D ratio than men. Recent studies on the relationship between 2D:4D ratio and gender-role orientation yielded rather inconsistent results. The present study examines the moderating influence of nationality on the relationship between 2D:4D ratio and gender-role orientation, as assessed with the Bem Sex-Role Inventory, as a possible explanation for these inconsistencies. Participants were 176 female and 171 male university students from Germany, Italy, Spain, and Sweden ranging in age from 19 to 32 years. Left-hand 2D:4D ratio was significantly lower in men than in women across all nationalities. Right-hand 2D:4D ratio differed only between Swedish males and females indicating that nationality might effectively moderate the sexual dimorphism of 2D:4D ratio. In none of the examined nationalities was a reliable relationship between 2D:4D ratio and gender-role orientation obtained. Thus, the assumption of nationality-related between-population differences does not seem to account for the inconsistent results on the relationship between 2D:4D ratio and gender-role orientation.

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