Susana Isabel Ferreira da Silva de Sá ESTROGÉNIOS E ...

74 S.I. SÁ AND M.D. MADEIRA
Fig. 4. Electron micrographs obtained from two consecutive serial
sections of the VMN showing symmetrical synaptic contacts (arrowheads)
between axon terminals and the soma (s) of a neuron of the
ventrolateral division of the VMN. The terminal which makes a synaptic
contact in A but not in B is indicated by an asterisk. Scale bar
0.5 m.
rats, and 3,800 (0.9) for male rats, and the mean somatic
volume was 2,430 m 3 (0.09), 1,755 m 3 (0.09), and 2,432
m 3 (0.07), respectively. No significant effects of sex and
hormonal levels on the numerical density of VMNvl neurons
were found (F (2,15) 3.13, P 0.073). Conversely, the
volume of the neuronal cell bodies differed among the
groups analyzed (F (2,15) 27.16, P 0.0005), with
proestrus rats and males having larger neuronal cell bodies
(38%, P 0.0005) than diestrus rats.
Synapse densities
As shown in Figure 5A, the numerical density of axospinous
synapses differs between the sexes, and between
females at different stages of the estrus cycle (F (2,15)
21.55, P 0.0005). The numerical density was significantly
higher in proestrus than in diestrus rats, and in
Fig. 5. Graphic representation of the morphometric data obtained
from axospinous (spinous), axodendritic (dendritic), and axosomatic
(somatic) synapses in the ventrolateral division of the VMN of male
rats, and female rats in diestrus and proestrus. Columns represent
means and vertical bars represent 1 SD. A: Numerical density of the
synapses. B: Number of synapses per neuron. Tukey’s post-hoc tests:
*P 0.05, **P 0.01, ***P 0.005, compared with male rats; P
0.05, P 0.01, P 0.005, compared with diestrus rats.
females than in males. Likewise, the numerical density of
axodendritic synapses was influenced by sex and phase of
the estrus cycle (F (2,15) 3.70, P 0.05). However, when
pairwise comparisons were performed, no significant differences
between proestrus and diestrus rats or between
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