FIGURE 1 | Histological sections of ovaries of Leporinus piau stained by HE. (A) Ovary in rest (F1) with initial perinucleolar oocytes (O1) containing basophilic cytoplasm and nucleus with various nucleoli and advanced perinucleolar ovocytes (O2) containing finely granular cytoplasm and nucleus with nucleoli close to the nuclear envelope. (B) Beginning of maturation with the appearance of pre-vitellogenic follicles with characteristic cortical alveoli (O3) in the peripheral ooplasm. (C) Maturation/mature (F2) with vitellogenic oocyte (O4) and cytoplasm filled with yolk globules, thin zona radiata (ZR), and squamous follicular cells. (D) Spawned (F3) with post-ovulatory follicles (POF) alongside follicles at all stages of development. (E) Detail of post-ovulatory follicle (POF). (F) Detail of atresic follicle (AF). Bars: A and B = 200µm; C = 300µm; D and F = 150µm; E = 50µm.