TESTICULAR MATURATION AND REGRESSION IN THE COMMON SNOOK

During the annual reproductive cycle, the lobular testis of Centropomu s undecimalis undergoes height, width, and morphological changes which reflect five reproductive classes: regressed; early, mid-, and late m aturation; and regression. Histological criteria, particularly differe nces between continuous and discontinuous,germinal epithelia, are used to distinguish these five classes, even though they are only referenc e points within the annual gonadal cycle. A mechanism for lobular grow th during early, mid-, and late maturation is presented; and it is hyp othesized that a permanent germinal epithelium first appeared in the f ishes. Throughout the year, periodic acid-Schiff-positive macro-melano phage centres and PAS-positive granulocytes are observed in the testis . They are most abundant after the breeding season, and they may be in volved in focal tissue degradation. (C) 1998 The Fisheries Society of the British Isles.