Biology Reference
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necessary. Elevation of the aromatase level in the brain and restoration
of masculine behavior of the castrated male show the rapid response in
S. salar
and
Hemihaplochromis multicolor
. However, Mayer et al. (1991)
and Reinboth (1972) have remained silent on the regeneration of testis
in these castrated fi shes (Table 29). Subjected to bilateral gonadectomy,
the responses of gonadal regeneration considerably differ one from the
other. The castrated
Oncorhynchus nerka
and ovariectomized
Oreochromis
niloticus
have regenerated testis and ovary, respectively confi rming the
decisive sex determination and retention of unisexual potency alone in
adults. The grass carp
Ctenopharyngodon idella
also belongs to this group, in
which sex is stably fi xed and adults retain unisexual potency alone.
C. idella,
Table 29.
Gonadectomy and regeneration in fi shes (from Pandian, 2011, modifi ed)
Species/Reference
Reported observations
Betta splendens
Noble and Kumpf (1937)*
Lowe and Larkin (1975)
65% surviving ovariectomized females regenerated
functional testes from the cut end of the remaining
oviduct or ovarian wall; crossed with normal females, the
regenerated males produced F
1
progenies at sex ratio of
0.43 ♀ : 0.57 ♂
Kaiser and Schmidt (1951)*
Crossed with normal female, the regenerated male sired
two broods of six and 102 all-female progenies
Noble and Kumpf (1937)*
Treated with E
2
, ovariectomized females failed to
regenerate ovary
Gambusia affi nis
Turner (1967)*
Castrated male apparently regenerated testis, as indicated
by the presence of small (4%) testis and complete
gonopodium
Oryzias latipes
Okada and Yamashita (1994)
Treated with E
2
, ovariectomized females failed to
regenerate ovary
Carassius auratus
Kobayashi M et al. (1991)
Treated with 11-KT, ovariectomized females regenerated
testes
Oncorhynchus mykiss
Kersten et al. (2001)
Castrated males regenerated testes, irrespective of
receiving E
2
-treatment. Ovariectomized neomales (XX)
regenerated testes
O. nerka
Robertson (1961)
Castrated males regenerated functional testes at 'wrong'
sites, i.e. adjacent to spermatic duct. Ovariectomized
females developed ovaries but with reduced fecundity
Oreochromis niloticus
Akhtar (1984)
67% of ovariectomized females regenerated ovaries within
119 days
Ctenopharyngodon idella
Underwood (1986)
The gonads including surrounding mesentery were
removed. Testes and ovaries were completely regenerated
in 91% males and 38% females, respectively
Salmo salar
Mayer et al. (1991)
Castrated male increased the aromatase activity in brain on
treatment with testosterone or 11-Ketoandrostenedione
Hemihaplochromis multicolor
Reinboth (1972)
Castrated male behaved completely as male following
injection of testosterone
*cited in Atz (1964)
