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The Biology of Sea Turtles, Vol. II
ing, and building the reserves in general preparation for their next reproductive
episode. The ovary of a reproductively quiescent turtle will contain no enlarged
yolk-filled follicles, but it will contain numerous postovulatory scars (corpora
albicantia) and scattered atretic follicles. The oviduct of a quiescent female is flaccid
in appearance, very convoluted, and pink adjacent to the ovary.
In quiescent males, seminiferous tubules are pale white to salmon. The epididymis appears pendulous but not turgid and tubules will not be visible; its color
is pale white.
7.6.5 BREEDING CONDITION
A variable proportion of the adult female and male turtles in the foraging areas
prepare for reproduction in any one year. For most green, loggerhead, and hawksbill
adult female turtles, this preparation requires in excess of a year, on the basis of
repeated examination via laparoscopy (Limpus, unpublished data). Before commencing vitellogenesis, the turtle must be sexually mature, have recovered from any
previous reproductive episode, and have accumulated enough energy (fat) reserves
to support vitellogenesis. Vitellogenesis requires the mobilization of stored energy
(fat) and its modification via the liver under the control of the endocrine system
with deposition into the previtellogenetic follicles. To prepare multiple clutches of
follicles to support a breeding season requires at least 8 months. The quality and
quantity of food are likely to play a major role in the timing of reproduction (Limpus
and Nicholls, 2000).
The ovary of a turtle preparing to breed contains several hundred externally
vascularized, yolk-filled follicles that are half a centimeter or more in diameter. It
may contain postovulatory scars (corpora albicantia) and scattered atretic follicles.
When the female commences her breeding migration from her foraging area, she
carries a full complement of mature-sized yolked follicles and numerous other lessthan-mature-sized follicles in each ovary. Once breeding has commenced after
migration and copulation, the internesting female’s ovary also contains increasing
numbers of corpora lutea and decreasing numbers of mature follicles as each clutch
is ovulated. The less-than-mature-sized follicles at the commencement of migration
do not mature during the breeding season and are resorbed. The oviduct of a
reproducing female is flaccid, having been stretched by the passage of eggs, or it
may contain eggs.
In the testis of breeding males, the seminiferous tubules are distended and white.
The coils of the epididymis appear turgid and enlarged, and the tubules are white
and externally visible. Wibbels et al. (1990) described timing of the spermatogenic
cycle in adult male loggerhead turtles preparing to breed. Histologically, the testis
can be identified as developing out of the quiescent phase about 8 months prior to
the courtship season, and has peak sperm production at about the time that migration
to the breeding area begins.
1123 book.book Page 218 Monday, November 11, 2002 11:11 AM
The Biology of Sea Turtles, Vol. II
ing, and building the reserves in general preparation for their next reproductive
episode. The ovary of a reproductively quiescent turtle will contain no enlarged
yolk-filled follicles, but it will contain numerous postovulatory scars (corpora
albicantia) and scattered atretic follicles. The oviduct of a quiescent female is flaccid
in appearance, very convoluted, and pink adjacent to the ovary.
In quiescent males, seminiferous tubules are pale white to salmon. The epididymis appears pendulous but not turgid and tubules will not be visible; its color
is pale white.
7.6.5 BREEDING CONDITION
A variable proportion of the adult female and male turtles in the foraging areas
prepare for reproduction in any one year. For most green, loggerhead, and hawksbill
adult female turtles, this preparation requires in excess of a year, on the basis of
repeated examination via laparoscopy (Limpus, unpublished data). Before commencing vitellogenesis, the turtle must be sexually mature, have recovered from any
previous reproductive episode, and have accumulated enough energy (fat) reserves
to support vitellogenesis. Vitellogenesis requires the mobilization of stored energy
(fat) and its modification via the liver under the control of the endocrine system
with deposition into the previtellogenetic follicles. To prepare multiple clutches of
follicles to support a breeding season requires at least 8 months. The quality and
quantity of food are likely to play a major role in the timing of reproduction (Limpus
and Nicholls, 2000).
The ovary of a turtle preparing to breed contains several hundred externally
vascularized, yolk-filled follicles that are half a centimeter or more in diameter. It
may contain postovulatory scars (corpora albicantia) and scattered atretic follicles.
When the female commences her breeding migration from her foraging area, she
carries a full complement of mature-sized yolked follicles and numerous other lessthan-mature-sized follicles in each ovary. Once breeding has commenced after
migration and copulation, the internesting female’s ovary also contains increasing
numbers of corpora lutea and decreasing numbers of mature follicles as each clutch
is ovulated. The less-than-mature-sized follicles at the commencement of migration
do not mature during the breeding season and are resorbed. The oviduct of a
reproducing female is flaccid, having been stretched by the passage of eggs, or it
may contain eggs.
In the testis of breeding males, the seminiferous tubules are distended and white.
The coils of the epididymis appear turgid and enlarged, and the tubules are white
and externally visible. Wibbels et al. (1990) described timing of the spermatogenic
cycle in adult male loggerhead turtles preparing to breed. Histologically, the testis
can be identified as developing out of the quiescent phase about 8 months prior to
the courtship season, and has peak sperm production at about the time that migration
to the breeding area begins.
1123 book.book Page 218 Monday, November 11, 2002 11:11 AM