One hundred ninety-one large scale menhaden, Brevoortia patronus, ranging in age from larvae to sexually mature females were used in this study. Collections were made in the littoral and shallow off shore waters of the Gulf of Mexico from Dauphin Island, Alabama, westward to West Bay, Louisiana, at intervals throughout a five year period. Using standard paraffin techniques a number of staining methods were employed. Cytological and histological accounts are presented of the tissue elements of the gonads beginning with inception in the larvae, sexual differentiation to the sexes, and the cyclic changes associated with oogenesis and spawning in the mature fish. The microscopic developments occurring during these periods are correlated with gross features of the organ, the ages of specimens, and with seasonal periods. An account of the morphology and physiology of atretic oocytes and ovulated follicles is presented. Using the ovarian components as an index, the time and duration of the spawning season is established as occurring from late October to February or early March with some variance due to environmental factors. From the study it is possible to postulate that this species exhibits intermittent total spawning in the Gulf
