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reverse gender to either sex on appropriate hormonal treatment during
the labile period (e.g., Kirankumar and Pandian, 2003; Balasubramani
and Pandian, 2008b). It is not clear whether the adults of these fi shes have
retained PGCs/OSCs. If the fi ghterfi sh has not retained these, how has it
regenerated the testis and the male sires male and female progenies, as has
been reported by Lowe and Larkin 1975, or only F 1 female progenies, as
reported by Kaiser and Schmidt 1951. In the context of PGCs/OSCs/SSCs
transplantation research to generate allogenics and xenogenics and their
importance in conservation of fi shes and aquaculture, it is important to
undertake more research to solve the riddles of the observations reported
from experimental gonadectomy studies in B. splendens .
At this juncture a review of Le Page et al. (2010) proposal of non-
sexualization of the brain and the consequent lability of sex differentiation
of teleost fi shes is to be reconsidered. In agreement with Le Page et al. (2010),
almost all the sequential and serial hermaphroditic fi shes undergo natural sex
change once in one direction and more times in either direction, respectively.
Among the simultaneous hermaphrodites too, the rivulus is hatched as a
female and becomes hermaphrodite, as it grows (Sakakura and Noakes, 2000);
a few gamete exchanging hermaphrodites also become males. Among the
sequentials, reports on the sex change by primary males and females are not
uncommon . Clearly, the window of brain sexualization covers almost the
entire life span and the brains are not sexualized in all the hermaphrodites.
Similarly the secondary gonochoric fi shes such as the goldfi sh have also
retained bisexual potency during the adult stage, for some of them reverse sex
during the adult stage, when subjected to hormonal induction (e.g., goldfi sh)
or social pressure (e.g., paradise fi sh, see Pandian, 2011). Being a secondary
gonochore (see Table 3), the germ cells supporting cells of C. auratus have
retained bisexual potency. Expectedly, the ovariectomized goldfi sh, following
11-KT treatment, regenerates the testis, as their germ cells supporting somatic
cells have retained bisexual potency (however see Yamaha et al., 2003;
see also Table 48, Pandian, 2011). Apparently, the germ cells supporting
somatic cells of secondary gonochores, from some hermaphrodites which
have evolved, have also retained bisexual potency. To date, the secondary
gonochores goldfi sh, zebrafi sh, and possibly secondary gonochoric platyfi sh,
paradisefi sh and checkerboard cichlid are the only gonochoric fi shes, which
have retained reversible brain sexualization and a long window of brain
sexualization (Fig. 56).
On the other hand, Le Page et al. (2010) conclusion that the brains of
gonochoric fi shes also remain non-sexualized and the window of their brain
sexualization includes the matured adult stage, needs further consideration.
The available evidences thus far reported do indicate that in these primary
gonochores, the window of unsexualized brain lasts only upto the juvenile
stage or at the best upto puberty and this duration is synchronized with
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