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4.3.4. Intra-ovarian periodicities and frequency of spawning
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To study the development of ova, the diameter of ova from immature to fully ripe and spent ovaries should be recorded using ocular micrometer. Ova-diameter measurements should be taken from 20-25 ovaries in each case.
Table 1. Stages of Maturation
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Sex
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Stage
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Description of Gonads
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|
Female
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I. Immature
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Ovary thin, narrow, cylindrical, occupying less than one-fourth of body cavity length, pale, translucent.
|
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II.Maturing virgins
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Ovary thin, narrow, cylindrical, occupying about one-fourth of body cavity, pale, translucent. Ova translucent, irregularly shaped and slightly yellow.
|
|
III. Maturing
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Ovary occupies about half of a body cavity, narrow, cylindrical and pale yellow. Blood capillaries not distinct, ova not clearly visible to the naked eye; larger ova opaque and smaller ones translucent.
|
|
IV. Mature
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Similar to that in stage III but with numerous blood capillaries. Majority of ova opaque and visible to the naked eye.
|
|
V. Gravid
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Ovary occupies about three-fourth of body cavity, whitish, with numerous blood capillaries; ovarian wall thin, ova spherical, opaque with narrow translucent outer border.
|
|
VI. Ripe
|
Ovary occupies from three-fourths to entire length of body cavity, cream-coloured. Ripe ova translucent and with or without distinct oil globules, already released into the lumen of the ovary, together with several mature (opaque) and maturing (translucent) ova.
|
|
VII. Spent
|
Completely spawned, ova never seen.
|
|
Male
|
I. Immature
|
Testis very small, narrow and thread-like, occupying one-fourth of body cavity.
|
|
II.Maturing virgins
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Testis slightly more enlarged than in stage 1 but essentially thread-like and transparent.
|
|
III. Maturing
|
Testis has begun to broaden and thicken, turning white in colour
|
|
IV. Mature
|
Testis, flat, thick and white; extends to more than half of body cavity
|
|
V. Gravid
|
Testis very thick, flat creamy-white; extends to two-thirds of body cavity, milt oozes freely.
|
|
VI. Ripe
|
No changes discernible in testis
|
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VII. Spent
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Testis has shrunk
|
|
Participants