sperm penetration assay

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sperm penetration assay (SPA)

a test for the ability of spermatozoa to penetrate oocytes in vitro. Hamster oocytes that lack the zona pellucida are exposed to the spermatozoa in question. Such zona-free oocytes can undergo heterologous membrane fusion with the membranes of spermatozoa that have undergone the acrosome reaction. An assessment is then made of the proportion of oocytes that have been successfully penetrated.

sperm penetration assay

A specialised fertility test that assesses sperm cell ability to fuse with (penetrate) an ovum (egg).

Human sperm are mixed with hamster eggs in vitro and the number of sperm that penetrate the egg (sperm capacitation index) is measured.

sperm penetration assay

A test to evaluate male fertility in which a sample of sperm is added to hamster eggs whose zona pellucida has been removed. The number of sperm that penetrate each egg is measured and compared to a normal value. Synonym: hamster zona-free ovum test
See also: assay


the male germ cell. See also spermatozoon.

sperm agglutinins
anti-sperm antibodies of the IgG class occur as autoantibodies in dogs infected with Brucella canis.
sperm capacitation
acquisition of the capacity to penetrate an ovum, not present at the time of delivery of the spermatozoon, and which requires a period of incubation in the female tract. It involves increased metabolic activity and motility and the removal of a chemical decapacitation factor from the spermatozoon. Capacitation must take place for the acrosome reaction to occur.
sperm concentration
a sperm count as measured in a hemocytometer; an indication of the health of the relevant testicles and a guide to the prospective fertility of the ejaculate and the donor.
sperm live-dead ratio
an indicator of the viability of the ejaculate as expressed in a slide count of a specially stained smear of the semen in which the dead and live sperm can be distinguished because of their differential staining.
sperm morphology
the normal anatomical structure of the spermatozoon. Abnormality of the structure of individual spermatozoa is used as a guide to the location and nature of the disease causing reduced reproductive efficiency.
Enlarge picture
Morphology of normal and abnormal canine spermatozoa. By permission from Nelson RW, Couto CG, Small Animal Internal Medicine, Mosby, 2003
sperm motility
the percentage of spermatozoa moving actively forward. Assessed under the microscope (400 × magnification) or by computerized imaging. See also wave motion; used to predict the probable fertility of the ejaculate.
sperm motility index
half the sum of the sample's sperm percentage motility + sperm progressive motility.
sperm penetration assay
see ovum penetration assay.
sperm stone
hard bodies composed of inspissated masses of spermatozoa found in dilated remnants of epididymal ducts and produced by chronic epididymitis.
sperm transport
within both male and female reproductive tracts some movement forward results from the movements of the spermatozoa but most progress is the result of peristaltic movements by the tubular organs in which the spermatozoa find themselves at the time.