Comparison of Oogenesis and Sex Steroid Profiles between Twice and Once Annually Spawning of Rainbow Trout Females (Oncorhynchus mykiss)

Figure 4

Histological sections of ovaries at different stages of development during oogenesis. (a), (c), (e), (g), (i): once spawners; (b), (d), (f), (h), (j): twice spawners. (a), (b): May; (c), (d): July; (e), (f): September; (g), (h): November; (i), (j): January. POF: postovulatory follicles; PNS: perinucleolar stage; VVS: vitellin vesicles stage; SVS: secondary vitellogenesis stage; ESVS: early secondary vitellogenesis stage; FMS: final maturation stage; ASVS: advanced secondary vitellogenesis stage. Bar scale represents 1,000 μm.

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(i)

(j)