Characterization of giant neuroendocrine cells in the pregnant New Zealand white rabbit vagina demonstrated by histological, histochemical, and immunohistochemical methods.

The vagina is part of the genitalia and constitutes part of the birth canal. Sperm is deposited into vagina, and it acts in transport of sperm. Pregnancy is a complex process involving different physiological changes in the body associated with hormonal and metabolic alterations that control maternal and fetal demands. During pregnancy, neuroendocrine cells in rabbit vagina are considered part of the diffuse neuroendocrine system observed throughout the body. Giant neuroendocrine cells in rabbit vagina during pregnancy have not been observed previously. This study detected the presence of giant neuroendocrine cells in the vagina of the pregnant rabbit. The presence of these cells was demonstrated with the use of different histological techniques, including hematoxylin and eosin, PAS, combined Alcian blue-PAS, Crossmon's trichrome, and the Grimelius silver method. Giant neuroendocrine cells were observed in late-pregnancy intraepithelial sites and on the lamina propria. These cells were characterized by vacuolated basophilic cytoplasm with PAS- and PAS-AB-positive granules. Moreover, neuroendocrine cells exhibited an argyrophilic character. Immunohistochemically, neuroendocrine cells in rabbit vagina during pregnancy demonstrated positive immunoreactivity to neuron-specific enolase (NSE) with different intensities, mild immunoreactivity to the vascular endothelial growth factor (VEGF), and negative immunoreactivity to CD68. HIGHLIGHTS: Neuroendocrine cells on the vagina of the female rabbit during pregnancy are considered part of the diffuse neuroendocrine system. Giant neuroendocrine cells on the vagina of the rabbit during pregnancy have not been observed previously. Giant neuroendocrine cells were demonstrated intraepithelial and on the lamina propria. Immunohistochemically, neuroendocrine cells demonstrated positive immunoreactivity to NSE and VEGF, and negative immunoreactivity to CD68.