Male reproduction
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Drawing of the cross section of the male reproductive tract |
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Outline of the male reproductive tract |
The rear of the male pig |
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The male reproductive tract dissected and labeled. |
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The male sex glands |
Detail of the medial view of the left testes |
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Detail of the medial view of the left testes |
Cut surface of the testes |
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Detail of a cross-section of the vas deferens |
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The preputial os |
The preputial diverticulum opened on the ventral surface |
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Collection of the boar |
Detail of the boar penis |
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Anatomy of the sperm |
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Sperm
Morphology
Down the microscope the
sperm should be seen to be active with forward motion. In very good samples wave motion is seen |
In contaminated samples
agglutination of sperm can be seen.
This can also occur with chilling |
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7μm 0.7μm 37.4 μm |
The normal sperm with a
tail central to the head. The tail is
straight without any kinks. The head
is a smooth even head. On the right we see proximal and distal cytoplasmic droplets. This may have little significant impact on fertility. The are more common in immature sperm. The droplet comes from the acrosome/head cover which uncovers at ejaculation and then runs down the tail |
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Head abnormalities are not
common. The photographs illustrate a range
of abnormalities. Detached heads can
be common in certain boars. If the
head is abnormal attachment in the oviduct and to the egg will be impaired. |
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Tail abnormalities are
common with the variety of bent and coiled tails. Deformities of the tail interferes with the sperms ability to
swim in the oviduct and through the zona pellucida |
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Poor semen collection
techniques will result in increased contamination of the sample. This may be recognised by the clear presence
of bacteria in the sample |
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Review collection routines.
Note preputial fluid will kill semen.
The semen sample may also smell |
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Using stains such as
Eosin/Nigrosin stain the sperm may be clearer. Some of the stains also allow an assessment of whether the
sperm were alive or dead. |
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The sample on the left
contain a dead sperm in the middle, one detached head, one bent tail and two normal sperm |
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What are the abnormalities
you can see in the sample on the right? |
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While semen morphology is interesting, please note that only in extreme cases can fertility be affected by abnormal sperm cells. Second samples should be examined if more than 30% of the sperms cells examined are abnormal.
Also note that a single examination may be almost meaningless. The identification of a sub-fertile boar takes several serial semen samples and record analysis
The female filters out many of the abnormal sperm as they enter the oviduct. It has been shown that in the horse, despite being inseminated with semen samples with 85% abnormal sperms, this resulted in 90% normal sperm in the oviduct.
Remember you are examining the population of sperm not the
individual