Glial and axonal perikaryal coverage and somatic spines in the posterodorsal medial amygdala of male and cycling female rats

ABSTRACT The posterodorsal medial amygdala (MePD) is a sex‐steroid‐sensitive area that modulates reproductive behavior in rats. The volume of the neuronal cell body, density of dendritic spines, and glial fibrillary acidic protein immunoreactivity are sexually dimorphic or affected by gonadal hormones in the MePD. Here we add new data to this panorama and describe the ultrastructure of the glial and axonal coverage of the perikaryal membrane and the somatic spines in the MePD of males and cycling females (in diestrus, early proestrus, late proestrus, and estrus). Transmission electron microscopy data (mean values from seven to 11 neurons per rat, five or six animals per group) showed that the rat MePD has most of the perikaryal membrane covered by glial processes and a relatively large amount (up to 40%) of axonal processes contacting the neuronal cell body. No statistically significant difference was found between groups for these somatic coverages (P > 0.5). However, the density of somatic spines along the length of the perikaryal membrane was higher in the late proestrus than in estrus (P