Plasma testosterone levels in the chick embryo

Woods, Jennifer; Simpson, R. Mark; Moore, Patricia

doi:10.1016/0016-6480(75)90076-3

Cited by 122 publications

(46 citation statements)

References 5 publications

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“…The tests on laterality concern the preferred use of the left or right eye in a variety of tests and their homology with visuospatial tasks in humans is not always clear. Moreover, the experimental treatment with androgens concern dosages above the normal physiological range of the species (see endogenous embryonic production as reported in Woods et al 1975;Tanabe et al 1979;Woods & Brazzil 1981).…”

Section: Discussionmentioning

confidence: 99%

Does testosterone affect lateralization of brain and behaviour? A meta-analysis in humans and other animal species

Pfannkuche

Bouma

Groothuis

2008

Phil. Trans. R. Soc. B

146

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Lateralization of brain and behaviour has been the topic of research for many years in neuropsychology, but the factors guiding its development remain elusive. Based on sex differences in human lateralization, four hypotheses have been postulated that suggest a role for androgens, specifically testosterone. With the discovery that lateralization is a fundamental principle in the organization of brain and behaviour among vertebrates, it has now become possible to experimentally test such hypotheses in animal models. The use of different taxa, humans, other mammalian species and birds (with oestradiol and not testosterone involved in sexual differentiation in birds) facilitates to differentiate between the hypotheses. We used meta-analyses for analysing papers that provided sufficient information, and a semi-quantitative approach based on all relevant studies that we extracted from the literature. We tested the predictions of these hypotheses regarding strength and direction of lateralization for motor output, language and visuospatial cognition in these three taxa. We tested for sex differences and early organizational effects of testosterone (both correlative and experimental studies). We found sex differences in the direction of lateralization for non-human mammals (motor biases similar to humans) and in direction and strength in birds (visual cognitive tasks). However, the prediction that prenatal testosterone exposure affects the direction of lateralization was not supported for humans. In birds and non-human mammals, opposite trends were found, with the effect in non-human mammals being opposite to the expectation based on sex differences. None of the four hypotheses was sufficiently supported and more studies, testing a wider array of functions in different taxa while reporting the data more completely are needed.

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Section: Discussionmentioning

confidence: 99%

Does testosterone affect lateralization of brain and behaviour? A meta-analysis in humans and other animal species

Pfannkuche

Bouma

Groothuis

2008

Phil. Trans. R. Soc. B

146

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“…Furthermore, in chicken embryos, endogenous production of steroids occurs as early as day 5 of development (Woods and Erton, 1978;Woods et al, 1975). The sex differences in yolk hormone content found by Petrie et al (2001) may therefore be the consequence of a difference in endogenous production between males and females.…”

Section: Endocrinologymentioning

confidence: 99%

Maternal androgens in egg yolks: relation with sex, incubation time and embryonic growth

Eising

Müller

Dijkstra

et al. 2003

General and Comparative Endocrinology

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“…Sexually dimorphic steroid concentrations in incubated eggs could be attributable to any of at least three sources: (i) a maternal sex-determining mechanism; (ii) sex differences in embryonic production of sex steroids, which ultimately accumulate in the yolk; or (iii) sex differences in sequestration or metabolism of sex steroids. Although Petrie et al (2001) emphasize the first explanation, avian embryos are known to produce sexually dimorphic levels of E2 (higher in female embryos) and T (higher in male embryos) by 7.5 days of incubation (Galli & Wasserman 1973;Woods et al 1975;Woods & Brazzill 1981;Ottinger et al 2001). Steroids are lipophilic and highly yolk-soluble, and easily cross biological membranes.…”

Section: Introductionmentioning

confidence: 99%

No sex difference in yolk steroid concentrations of avian eggs at laying

2005

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Yolk steroids of maternal origin have been proposed to influence genetic sex determination in birds, based on sex differences in yolk steroid concentrations of peafowl eggs incubated for 10 days. More recent reports dispute this proposal, as yolk steroids in eggs incubated for 3 days do not show such sex differences. To date, research examining this phenomenon has only analysed incubated eggs, although sex in avian species is determined before incubation begins. This may be a serious methodological flaw because incubation probably affects yolk steroid concentrations. Therefore, we investigated sex differences in yolk steroid concentrations of unincubated avian eggs. We withdrew yolk for steroid analysis from fresh, unincubated Japanese quail (Coturnix japonica) eggs by biopsy, and then incubated those eggs for 10 days, after which we harvested the embryonic material for genetic sexing and the incubated yolk for further steroid analysis. We found no sex differences in fresh Japanese quail eggs; however, sex differences were apparent in yolk steroids by day 10 of incubation, when female eggs had significantly more oestrogen in relation to androgen than male eggs. Concentrations of all yolk androgens decreased dramatically between laying and day 10 of incubation, whereas oestradiol (E2) concentrations increased marginally. Thus, yolk concentrations of androgens and E2 do not appear critical for avian sex determination.

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Plasma testosterone levels in the chick embryo

Cited by 122 publications

References 5 publications

Does testosterone affect lateralization of brain and behaviour? A meta-analysis in humans and other animal species

Does testosterone affect lateralization of brain and behaviour? A meta-analysis in humans and other animal species

Maternal androgens in egg yolks: relation with sex, incubation time and embryonic growth

No sex difference in yolk steroid concentrations of avian eggs at laying

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