Biology Reference
In-Depth Information
C
A
B
T
T
VT
O
O
10mm
1mm
1mm
Fig. 51.
Saffl amen chrysopterus
: Schematic representation of (A) gonads of a juvenile with female
coloration, (B) a breeding female and (C) a breeding male O = ovarian part; VT = vestigial
testicular tissue; T = testicular tissue (from Takamoto et al., 2003)
Considering the groupers as a model, and major events in ovarian
differentiation, ovarian degeneration and testicular re-differentiation
in protogynous species are briefl y summarized in Table 28. In some sex
changers, the transition in body color concomitant with sex change is
spectacular; a large number of such astounding examples are illustrated by
Lieske and Myers (1996), which may indicate the internal gonadal status
of the transitional. For recent information, Reinboth and Brusle-Sigard
(1997), Ohta et al. (2003) and Kline et al. (2011) may be referred. For more
information on details of the ovarian transformation to testis, Pandian (2010)
may be consulted. During the sex change, the testicular tissues develop from
the former ovarian wall or proliferate from the wall bordering the ovarian
Table 28.
Major events in ovarian differentiation in
Epinephelus coioides
, de-differentiation in
E. tauvina
and testicular re-differentiation in
E. fuscoguttatus
(compiled from Liu and Sadovy
de Mitcheson, 2009; Mathew, 2011; Pears et al., 2007)
Ovarian differentiation
Ovarian de-differentiation
Testicular re-differentiation
Gonadal primordium,
undifferentiated gonad
Ovary loose-walled,
elongated and compressed
Testis elongated to a cleft
or triangular, crypts of
precocious spermatocytes and
precursor testicular tissue
appear
Ovarian phase 1-2 gonad,
undifferentiated juvenile
Yellow brown bodies appear,
emergence of granulocytes
Crypts of spermatozoa joined
within testicular lobules to
form central sperm sinuses
Ovarian phase 3 gonad,
differentiating female
Atresia and degeneration of
peri-vitelline and chromatin
nuclear oocytes, gonad with
intermingled spermatogonial
tissue
Sperm ducts are formed,
brown bodies and ovarian
cavity persistent
Functional ovary
Oocytes reduced and
fi lled with vacuoles,
spermatogonia and
spermatocytes present
Functional testis
