2. STRUCTURE OF THE MALE REPRODUCTIVE SYSTEM
The basic component of the
male reproductive system is
the testis (Fig. 1A), suspended
in the body cavity by tracheae
and fat body. The more
primitive apterygote insects
have a single testis, and in
some lepidopterans the two
maturing testes are
secondarily fused into one
structure during the later
stages of larval development,
although the ducts leading
from them remain separate.
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3. STRUCTURE OF THE MALE REPRODUCTIVE SYSTEM
However, most male insects have a pair of testes, inside
of which are sperm tubes or follicles that are enclosed
within a membranous sac. The follicles connect to the
vas deferens by the vas efferens (Fig. 1B), and the two
tubular vasa deferentia connect to a median
ejaculatory duct that leads to the outside.
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4. STRUCTURE OF THE MALE REPRODUCTIVE SYSTEM
A portion of the vas deferens is often enlarged to form
the seminal vesicle, which stores the sperm before they
are discharged into the female. The seminal vesicles
have glandular linings that secrete nutrients for
nourishment and A portion of the vas deferens is often
enlarged to form the seminal vesicle, which stores the
sperm before they are discharged into the female. The
seminal vesicles have glandular linings that secrete
nutrients for nourishment and maintenance of the
sperm.
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5. Female reproductive system
The female reproductive system
consists of a pair of ovaries which
are subdivided into smaller units
called ovarioles, where the eggs are
produced. During egg production
(called oogenesis), the germ cells in
the germarium divide by mitosis to
form oocytes(eggs). The oocytes
undergo meiosis and continue to
increase in size by absorbing yolk
produced by adjacent cells. As the
oocytes grow they are pushed
downward by the continual cell
division in the germarium. Thus the
oocytes form chains, with the
youngest/smallest cells at the top
and mature/large cells at the
bottom.
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6. Female reproductive system
Once mature, an egg leaves the ovary via the lateral
oviduct and continues through the common
oviduct which opens into agenital chamber (called
the bursa copulatrix). This is where the male deposits
his spermatophore during copulation. The female uses
peristaltic contractions to move the spermatophore
into the spermatheca, where it is stored until it is
needed. Thespermathecal gland produces nutrients
in order to keep the sperm alive in the spermatheca,
where sperm can survive for weeks, months or even
years.
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7. Female reproductive system
When the egg enters the genital chamber it passes across the
spermatheca and stimulates the release of sperm cells onto the
egg surface. The sperm cells enter the egg through the micropyle,
a small opening on the egg surface, and when the nuclei of
sperm and egg fuse, the egg is fertilised. Oviposition (egg laying)
soon takes place following fertilisation.
Once mature, an egg leaves the ovary via the lateral
oviduct and continues through the common oviduct which
opens into agenital chamber (called the bursa copulatrix). This
is where the male deposits his spermatophore during copulation.
The female uses peristaltic contractions to move the
spermatophore into the spermatheca, where it is stored until it
is needed.
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8. Female reproductive system
When the egg enters the genital chamber it passes
across the spermatheca and stimulates the release of
sperm cells onto the egg surface. The sperm cells enter
the egg through the micropyle, a small opening on the
egg surface, and when the nuclei of sperm and egg
fuse, the egg is fertilised. Oviposition (egg laying)
soon takes place following fertilisa
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