The term medial amygdalar nucleus (MEA) refers to a composite structure of the amygdala defined on the basis of Nissl stain. In the human ( Mai-1997 ) and the macaque ( Amaral-1992 ), the rat ( Swanson-2004 ) and the mouse ( Hof-2000 ). In the primate, it consists of two parts, the anterior part of the medial amygdalar nucleus (MEAa) and the posterior part of the medial amygdalar nucleus (MEAp). In the rodent it is subdivided into five parts: the anterodorsal part of the medial amygdalar nucleus (MEAad), the anteroventral part of the medial amygdalar nucleus (MEAav), the posterodorsal part of the medial amygdalar nucleus (MEApd), the posteroventral part of the medial amygdalar nucleus (MEApv) and the nucleus of the accessory olfactory tract (OLTa). Classically the primate MEA has been categorized as part of the corticomedial nuclear group ( Carpenter-1983 ). In the rodent it is classified as part of the extended striatum ( Swanson-2004 ). Functionally it is classified as part of the olfactory system (OLS) (NeuroNames). Neurons in the MEA and adjacent amygdalohippocampal area (AHI) have the highest levels of androgen and estrogen receptors of any nucleus in the amygdala ( Simerly-1990 ). The hormonal signals those receptors detect presumably enable the addition of self-sex information to sensorimotor signals processed through them. Thus, it is reasonable to consider that The evaluation of social oderants (pheromones) for differences between sexually immature and adult members of one's species and between male and female adults may occur in the MEA, Updated 14 Aug 2024.