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When performing cryopreservation of semen, it is the sperm quality after reviving the sample that is of importance, because many sperm cells die in the process. To be of use in assisted reproductive technology , the sample should after thawing have more than 5 million motile sperm cells per ml with a good grade of mobility.
A routine semen analysis should include: physical characteristics of semen (color, odor, pH, viscosity and liquefaction), volume, concentration, morphology and sperm motility and progression. To provide a correct result it is necessary to perform at least two, preferably three, separate seminal analyses with an interval between them of seven ...
A 2001 review on variation in semen quality and fertility by male age concluded that older men had lower semen volume, lower sperm motility, a decreased percent of normal sperm, as well as decreased pregnancy rates, increased time to pregnancy and increased infertility at a given point in time. [55]
It is advised to check the references for photos of reaction results. [1] Reagent testers might show the colour of the desired substance while not showing a different colour for a more dangerous additive. [2]
However, penis size may have been subject to natural selection, rather than sexual selection, due to a larger penis' efficiency in displacing the sperm of rival males during sexual intercourse. A model study showed displacement of semen was directly proportional to the depth of pelvic thrusting, as an efficient semen displacement device. [28]
] This may be explained by the fact that sperm banks only accept donors who have good semen quality, and because of the rigorous screening procedures which they adopt, including a typical age limitation on sperm donors, often limiting sperm donors to the ages of 21–39 (see paternal age effect), and genetic and health screening of donors. In ...
The sperm cell of Homo sapiens is the small reproductive cell produced by males, and can only survive in warm environments; upon leaving the body, it starts to degrade, thereby decreasing the total sperm quality. Sperm cells normally come in two types, "female" and "male", named for the resulting sex of the fertilized zygote each produces after ...
A represents the dominant allele for color (yellow), while a represents the recessive allele (green). If each plant has the genotype RrAa, and since the alleles for shape and color genes are independent, then they can produce four types of gametes with all possible combinations: RA, Ra, rA, and ra.