Article

Sex-dependent structural asymmetry of the medial habenular nucleus of the chicken brain.

Monash University
Cell and Tissue Research (impact factor: 3.11). 02/1985; 240(1):149-52. DOI:10.1007/BF00217568 pp.149-52
Source: PubMed

ABSTRACT An investigation of structural asymmetry in the avian brain was conducted on the epithalamic medial habenular nucleus of the chicken. Twelve male and ten female two-day-old chickens were used for a morphometric evaluation of asymmetry. The medial habenular nucleus was measured from paraffin-wax-embedded, 8 micron-thick sections by use of a semiautomatic image analyser. The volumes of the right and left medial habenula of each animal were statistically analysed ('within animal experimental design'). The right medial habenula in males showed significant group asymmetry. In contrast, females failed to demonstrate group bias in favour of either hemisphere. However, individual females were lateralised, with either a larger right or left medial habenula. Although individuals of both sexes were lateralised, there was no significant sex difference in volume in either the right or left medial habenula. We propose that sex-linked structural asymmetry may be influenced by steroid hormonal effects in the central nervous system, and that such asymmetry could be more prevalent in the non-mammalian vertebrate brain than previously considered.

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Keywords

'within animal experimental design'
 
8 micron-thick sections
 
central nervous system
 
epithalamic medial habenular nucleus
 
female two-day-old chickens
 
individual females
 
medial habenula
 
medial habenular nucleus
 
morphometric evaluation
 
prevalent
 
sex-linked structural asymmetry
 
sexes
 
significant sex difference
 
steroid hormonal effects
 
structural asymmetry
 
volumes
 

C J Gurusinghe