Yoneda et al.: Reproductive cycle, fecundity, and seasonal distributions of Lophius litulon 
361 
in size until it disappears (Fig. 40. Ultimately, the 
granulosa cell layer becomes indistinct and the thecal 
cell layer is much regressed. 
Maturity stages of testes 
The testes can be classified into four stages of matu- 
rity according to their histological characteristics. No 
spent specimens, defined as those in which spermato- 
genesis has ceased and residual spermatozoa remain in 
the testis, were found during the study. 
Stage 1 immature (Fig. 5A): Germinal cysts containing 
spermatogonia, spermatocytes, and spermatids are 
observed along the wall of the seminiferous tubules. Sper- 
matids and spermatozoa are not present in the lumina 
of the seminiferous tubules and the small main duct. All 
specimens with testes at this stage were <306 mm TL. 
Stage 2 early spermatogenesis (Fig. 5B ): Germ cells at 
al! stages of spermatogenesis are present. Spermatids 
and a few spermatozoa are observed in the lumina of 
the seminiferous tubules and main sperm duct. 
Stage 3 late spermatogenesis (Fig. 50: Active sper- 
matogenesis occurs in the testes. Spermatids and sper- 
matozoa are more abundant in the lumina of the 
seminiferous tubules and in the main sperm duct than 
in the previous stage. 
Stage 4 mature (Fig. 5D): Large quantities of sperma- 
tozoa and a few spermatids are present in the lumina 
of the seminiferous tubules and main sperm duct. Sper- 
matogenesis and spermatogonial division also occurs in 
the seminiferous tubules, though few, if any, germinal 
cysts containing spermatogonia or spermatocytes are 
found around the main sperm duct. 
Maturity stages of ovaries 
The ovaries can be classified into six stages of maturity 
according to their histological characteristics and the de- 
velopment of the most advanced oocytes. The classification 
of stage-4, -5, and -6 ovaries is based on a modification of 
the atretic states of Hunter and Macewicz (1985). 
Stage 1 immature (Fig. 6A): Only previtellogenic oocytes 
are present and the epithelia of both the ovigerous lamel- 
lae and ovarian wall are thin. 
Stage 2 developing (Fig. 6B ): Most advanced oocytes have 
reached the primary to tertiary yolk stages. All of the ovig- 
erous lamellae have vitellogenic oocytes. This stage can be 
subdivided into early and late stages. The early stage is 
defined by the presence of primary or secondary yolk stage 
oocytes and the late stage by the presence of tertiary yolk 
stage oocytes with gelatinous material. 
Stage 3 mature (Fig. 60: The most advanced oocytes 
are in the migratory nucleus or mature stages. The ovu- 
A B 
Figure 3 
Photomicrographs of the ovigerous lamellar epithelium and 
ovarian wall epithelium at various stages of ovarian matu- 
ration in Lophius litulon. (A) Ovigerous lamellar epithelium 
(ole) at the previtellogenic stage. (B) Ovarian wall epithelium 
(owe) at the previtellogenic stage. (A) and (B) show the epithe- 
lial cells of both the ovigerous lamella and ovarian wall are 
squamous or cuboidal in shape and contain a small nucleus. 
(C) Ovigerous lamellar epithelium at the tertiary yolk stage. 
(B) Ovarian wall epithelium at the tertiary yolk stage. (C) and 
(D) show that gelatinous material is actively secreted from the 
apical surfaces of the epithelia of both the ovigerous lamellae 
and ovarian wall. Bar = 25 pm; gm = gelatinous material. 
lated oocytes are found in the gelatinous material form- 
ing within the ovarian lumen just before spawning. A part 
of the remaining smaller oocytes contains early yolk stage 
oocytes. 
Stage 4 spawning (Fig. 6D): Vitellogenic oocytes with 
no sign of atresia and postovulatory follicles are present. 
Degenerating residual mature oocytes are frequently 
observed. More than 50% of the ovigerous lamellae have 
vitellogenic oocytes. 
Stage 5 spent (Fig. 6E): Vitellogenic oocytes are degener- 
ating (early atretic stage) and postovulatory follicles are 
observed. More than 50% of the ovigerous lamellae have 
only previtellogenic oocytes or atretic oocytes (or both). 
Stage 6 resting (Fig. 6F): Late atretic stage oocytes and 
previtellogenic oocytes are present, and the epithelia of 
both the ovigerous lamellae and ovarian wall are thin. 
To determine how frequently ovigerous lamellae were 
found with yolked oocytes after spawning, 30-50 oviger- 
ous lamella samples from the ovaries of 18 females with 
