Preliminary observations on the fine structure of the medial preoptic nucleus in Coturnix japonica.

The organization of the sexually dimorphic medial preoptic nucleus of the Japanese quail was studied at ultrastructural level. The region was characterized by clusters of parvocellular neurons showing a rich supply of axo-somatic synapses and a peculiar distribution of synthetic (rough endoplasmic reticulum) and secretory (Golgi complexes) structures. Further analyses are required to relate these features with sex, hormonal status and sexual behaviour of quail.