Aim To investigate the gender differences in electrophysiology and neuroanatomy of myelinated and unmyelinated visceral and baroreceptor afferent neurons(VANs and ABNs) of adult rats.Methods VANs and ABNs were isolated enzymatically and Vagus-nodose slice preparation was also applied in this study.For identification of ABNs,aortic depressor nerve(ADN) was labeled using fluorescent dye.Whole-cell patch technique was used to record action potential(AP).Electronic microscopy was selected for morphological analysis of ADN.Results(1) A-and C-type VANs were identified and significant differences of AP discharge profiles between female and male were not established;(2) except for the traditionally classified A-and C-types,myelinated Ah-type VGNs were also identified with faster conduction velocity,lower firing threshold,and higher neuronal excitability.Importantly,these Ah-types were found in female rats with a similar frequency like A-types but rarely seen in males.(3) Ah-type ABNs were also identified by fluorescence.(4) Morphological data showed that myelinated fiber in ADN was ~25% of total and this result was consistent with our electrophysiological data.(5) Firing frequency of Ah-types(20~40 Hz) was lowered than that of A-types(40~150 Hz,P