182
._
Shelton
exogenous
steroids. The induction of G°D. proceeds within two broad
gonadogenesis and gametogenesis (Persov, 1972, 1975) ; primary germ
arise in an undiffèrentiated gonadal precursor, proliferate mitotically
then as meiosis is initiated, the goneCytes are recognizableas
or
oocytes. In some fishes,
G.D.
can be further
subdivided into
and cytological differentiation, where somatic structure may signal the direc—
tion of subsequent phenotypic sexual development° This sequence of
cytological differentiation has been described
common
carp
(Bobr0va, 1969 ; Pospisil and Smisek, 1971 ; Davies and
1980
;
Ryanzantseva and Sakun, 1980), grass carp (Jensen and Shelton,
and silver carp (Mirza and Shelton, in prepÇ);
G.D.
is a developmental process that is related to both age and size but
neither is totally satisfactory as an indicator of the stage of
Galkina (1964) indicated that the relationship between growth and physiologi—
cal development had received insufficient attention. Thus climate,
density and feeding level can affect growth and alter the
tionship to G°D. Jensen and Shelton (1983) described this effect in
carp
;
development was retarded in slow—growing fish but with fish of the
same
size, older ones had more advanced development° This was pertinent
age/size of steroid treatment for seX inversion° Despite this caveat, length
is a convenient means of estimating the progress of G,D. Cytological
rentiation in goldfish was proceeding at about 25 mm TL (equals 18 mm
Carlander, 1969) (Stromsten, 1931). Common carp gonadal development was
usually expressed in terms of age, but generally, cytological differentiation
did not occur at less than about 40.mm (Davies and Takashima, 1980).
Chinese carps differentiate much larger ; in grass carp, oogonia
into oocytes between 130 and 150 mm (Jensen and Shelton, 1983) and begin
silver carp at about 135 mm (Mirza and Shelton, in
or.occured between“
138 and 160 mm (112—132 mm SL) (Yemelyanova,.
1969). The physiological
cess
of G.D. is pertinent u>steroid sex inversion as the hormone must be.__Î
delivered at an appropriate level throughout this period of labile
ment (Yamamoto,
…
…
-,
.
l
j
'
«
È;Ë
on
the premise that there is
labile”period during G;Dç when eX0genOus forces can induce phen0typic deVé-'
10pment ëQhtïärÿ to the genotypiC‘sex. Yamamoto“(l969) proposed that steroids
act
if adequate physiological
d?liveïed
the labile period. Schreck (1974) reviewed those studîés
that involved administering'stéfbids“t0'fishl Hunter and Donaldson (1983) ”'
thé results of steroid treatment @@ economically important‘fishèsu
'Ihéy
coéiderations that must be
protocol;
**
,
Ïh3:
fis & Prime—% cC:°I1$iîd<äæt£0hrf@æ
as well …as biological
& dire ;,meàns of monosexing & group
°f fi$«h- 01”
m &: pr0gramthatw1ll use
fish as, br00dstî°°k'
Thus
of. &;
depend
the
sex desired in
,
,.r61ation
QQDÈÇXÈ; the period of
Will
determine the
treatmentduration as
as initiation and L ;»
alternative delivery route
to
the more usual
This choice may influenCe the Stér01d
and the level of admihistration_; When fed, synthetic compounds are more
eff1cacious than comparable natural dues;
by the
_1ev‘ë1
‘."
“can "be
sex nvtdt 1tv1y1w lvl mpdth1d Variables that
affeçt_
may alter ? the
à parti cular
'
temperature Should
be
dd Fth1w … mv bnfftv pdv…
._
Shelton
exogenous
steroids. The induction of G°D. proceeds within two broad
gonadogenesis and gametogenesis (Persov, 1972, 1975) ; primary germ
arise in an undiffèrentiated gonadal precursor, proliferate mitotically
then as meiosis is initiated, the goneCytes are recognizableas
or
oocytes. In some fishes,
G.D.
can be further
subdivided into
and cytological differentiation, where somatic structure may signal the direc—
tion of subsequent phenotypic sexual development° This sequence of
cytological differentiation has been described
common
carp
(Bobr0va, 1969 ; Pospisil and Smisek, 1971 ; Davies and
1980
;
Ryanzantseva and Sakun, 1980), grass carp (Jensen and Shelton,
and silver carp (Mirza and Shelton, in prepÇ);
G.D.
is a developmental process that is related to both age and size but
neither is totally satisfactory as an indicator of the stage of
Galkina (1964) indicated that the relationship between growth and physiologi—
cal development had received insufficient attention. Thus climate,
density and feeding level can affect growth and alter the
tionship to G°D. Jensen and Shelton (1983) described this effect in
carp
;
development was retarded in slow—growing fish but with fish of the
same
size, older ones had more advanced development° This was pertinent
age/size of steroid treatment for seX inversion° Despite this caveat, length
is a convenient means of estimating the progress of G,D. Cytological
rentiation in goldfish was proceeding at about 25 mm TL (equals 18 mm
Carlander, 1969) (Stromsten, 1931). Common carp gonadal development was
usually expressed in terms of age, but generally, cytological differentiation
did not occur at less than about 40.mm (Davies and Takashima, 1980).
Chinese carps differentiate much larger ; in grass carp, oogonia
into oocytes between 130 and 150 mm (Jensen and Shelton, 1983) and begin
silver carp at about 135 mm (Mirza and Shelton, in
or.occured between“
138 and 160 mm (112—132 mm SL) (Yemelyanova,.
1969). The physiological
cess
of G.D. is pertinent u>steroid sex inversion as the hormone must be.__Î
delivered at an appropriate level throughout this period of labile
ment (Yamamoto,
…
…
-,
.
l
j
'
«
È;Ë
on
the premise that there is
labile”period during G;Dç when eX0genOus forces can induce phen0typic deVé-'
10pment ëQhtïärÿ to the genotypiC‘sex. Yamamoto“(l969) proposed that steroids
act
if adequate physiological
d?liveïed
the labile period. Schreck (1974) reviewed those studîés
that involved administering'stéfbids“t0'fishl Hunter and Donaldson (1983) ”'
thé results of steroid treatment @@ economically important‘fishèsu
'Ihéy
coéiderations that must be
protocol;
**
,
Ïh3:
fis & Prime—% cC:°I1$iîd<äæt£0hrf@æ
as well …as biological
& dire ;,meàns of monosexing & group
°f fi$«h- 01”
m &: pr0gramthatw1ll use
fish as, br00dstî°°k'
Thus
of. &;
depend
the
sex desired in
,
,.r61ation
QQDÈÇXÈ; the period of
Will
determine the
treatmentduration as
as initiation and L ;»
alternative delivery route
to
the more usual
This choice may influenCe the Stér01d
and the level of admihistration_; When fed, synthetic compounds are more
eff1cacious than comparable natural dues;
by the
_1ev‘ë1
‘."
“can "be
sex nvtdt 1tv1y1w lvl mpdth1d Variables that
affeçt_
may alter ? the
à parti cular
'
temperature Should
be
dd Fth1w … mv bnfftv pdv…