European Journal of Anatomy

Official Journal of The Spanish Society of Anatomy
Cover Volume 2 - Number 1
Eur J Anat, 2 (1): 15-21 (1998)

Sex differences in synaptic density in the prenatal rat striatum

T.L. Trips, W. Podschuweit, C. Pilgrim and I, Reisert

Abtei/ung Anatomie und Zeítoioiogie, Unlversttéi U/m, 0-89069 U/m, Germany.

ABSTRACT In order to elucidare the developmental mecha­ nisms responsible for sexual differentiation of the striatum, the ultrastructure of the stríarum of embr­ yonic clay (E) 18 and 21 rats was exarnined for sex differences in clensities of synapses. While the E18 striarum clisplayed very few contacts resembling mature synapses, the E21 stríatum containecl numerous synapses enabling clear clistinctions to be made berween asymmetrical Gray type I and symmetrical Gray type II synapses. The vast majo­ rity of all synapses counted were asymmetrical Gray type 1. In both sexes, the synaptic clensities exhibited large regional variations. The highest densities were present in the ventrocentral and the lowest in the medial regions of the E21 striatum. Marked sex clifferences were detectecl in the ven­ tral and lateral portions throughout the rostrocau­ dal extent of the striatum, With both synaptic subrypes, the sex ratio was 1.5 in favor of females. We argue that these sex differences reflect sexually-dimorphic inputs from the cortex as well as fromthe midbrain. Since the sex differences occur at the very beginning of the critical periocl for sex dif­ ferentiation of the rar brain, they are presumably instrumental in establíshing a sexually dimorphic circuitry in the striatum.

Keywords: Electron rnicroscopy - morphometry - development - critical periocl - basal ganglia.

European Journal of anatomy
ISSN 2340-311X (Online)