Estrogen receptor-alpha-immunoreactive neurons in the periaqueductal gray of the adult ovariectomized female cat

Anatomical and physiological studies in rodent and cat have shown that distinct parts of the midbrain periaqueductal gray (PAG) are important for the estrogen dependent, female reproductive behavior. The present study gives a detailed overview of the estrogen receptor-alpha-immunoreactive (ER-IR) neurons in the PAG in the cat. ER-IR neurons were found throughout the rostrocaudal extent of the PAG and laterally adjacent tegmentum, but were most numerous at caudal levels. The lateral and dorsal PAG contained most ER- IR neurons, whereas moderate numbers were found dorsolaterally. In these areas, only very few ER-IR neurons were found near the border of the ependymal layer. Except for the rostral dorsal raphe nucleus, the ventral PAG contained only few ER-IR neurons.