Abstract: In the teleost Mugil soiuy, six (or seven) morphological endocrine cell types could be distinguished with the electron microscope. Each of these was identified with one of the six (or seven) cell-types distinguished with the light microscope. Corticotrophs and prolactin cells form the pro-adenohypophysis; the meso-adenohypophysis consists of the gonadotrophs, growth hormone cells and thyrotrophs; and the meta-adenohypophysis consists of Ml and M2 cell types. The ultra structure features of each cell type are described in detail, and discussed in comparison with the homologous cells described in other teleosts. There is consistency between different teleosts in the ultrastructure of each cell type.