Biology Reference
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On the other hand, secondary or undifferentiated gonochorism
exists, when genotypic and phenotypic sexes differentiate in parallel
lines for a short or longer duration but only one sex, as genetically or
environmentally determined, becomes functional and the other becomes
latent with persistent useful (e.g.,
Nemipterus bathybius
, Takahashi et al.,
1989) or vestigial tissue, or may not persist. Intersexuality is the presence
of both male and female characteristics or of intermediate sexuality in a
single individual. All simultaneous hermaphrodites are intersexes but some
intersexes are not simultaneous hermaphrodites. The essential difference
is the mutual tolerance between the two opposing sexual tendencies in
simultaneous hermaphroditism. On the other hand, intersexuality is
the result of interference between the two opposing sexual tendencies;
consequently, neither of them can express themselves decisively and remain
non-functional. Notably, the ontogenetic pathway of sex differentiation is
interrupted by a duration of non-functional ovarian or intersexual phase,
which may be better named as rudimentary hermaphroditism, or juvenile
hermaphroditism. The term rudimentary hermaphroditism is defi ned as
the existence of non-functional hermaphroditism
prior to puberty
and that
of intersexuality to the transitional stage existing in a sex changing
mature
adult
. Juvenile hermaphroditism refers to the existence of all juvenile
females with ovary and its cavity, from which presumptive males arise by
the transformation of the ovary into functional testis. These restrictions
and defi nitions have become necessary, as authors indiscrimately and
confusingly use various terms such as 'juvenile intersexuality', 'juvenile
hermaphroditism', 'rudimentary hermaphroditism', 'non-functional
intersex', 'juvenile bisexuality' and so forth (see bold lines in Tables
3, 4, 5).
Depending on the duration of the existence of hermaphroditism and
others, secondary gonochorism is divided into four types:
Type 1.
Somatic
(intersexuality)
hermaphroditism
(Takahasi and Maeno, 1986),
in which the presence of ovarian lumen is recognizable in all individuals
(Fig. 3) but it may only be persistent in others, and may even be useful
as a testicular cavity, formed in a similar manner as the ovarian cavity, as
in
Pseudorasbora parva
(Table 3). However, the cavity is not detectable in
others such as
Carassius auratus
and
Rhodeus ocellatus ocellatus
due to the
overgrowth of testis. Some germ cells in differentiating testes undergo
oogenesis in many cases.
Type 2.
Late gonochorism
, in which the duration of the rudimentary
hermaphroditism is not transient as in somatic hermaphroditism, but lasts
upto sub-adult or puberty stage of the fi sh (Fig. 3). With their delimited
type of gonad, the sparid panga
Pterogymnus laniarius
and bronze bream
Pachymetopon grande
are good examples (Table 3). The hermaphroditism
