HISTOLOGICAL ANALYSIS OF GONADAL DEVELOPMENT IN PATAGONOTOTHEN-TESSELLATA (RICHARDSON 1845) (NOTOTHENIIDAE, PISCES) FROM THE BEAGLE-CHANNEL, ARGENTINA

Histological analysis of gonadal development in Patagonotothen tessell ata (Richardson 1845) was carried out over a 3-year period (1987-1989) on samples from the Beagle Channel, Tierra del Fuego, Argentina. Test icular structure is defined as of the 'unrestricted spermatogonial typ e'. Maturation processes of cysts are synchronized in the various tubu les, This degree of synchronization, as well as the characteristic of the different cellular types, permits definition of four spermatogenet ic stages. Patagonotothen tessellata is defined as a total spawner acc ording to ovocitary development and oocyte diameter frequency distribu tion analyses. Oocyte reabsorption and the likely consequences thereof on reproductive potential are also analysed. Patagonotothen tessellat a is the first species of Nototheniids for which annual double spawnin g (winter and summer) and non-biennial gonadal maturation processes ar e described.