Sperm morphology – sperm neck

Sperm morphology is a part of semen analysis test which is a type of laboratory test. Semen analysis is done to evaluate features of semen fluid and sperm cells. Semen analysis is done to diagnose male type infertility and success of vasectomy operation which is a type of birth control method.

Sperm morphology means sperm shape. Sperm cell should  have a proper shape to swim and move to the egg and fertilize it. Sperm cell have 4 parts;

  • Sperm head; that contains the DNA
  • Sperm neck; the part that has centrosome and centrioles
  • Sperm mid-piece contains mithocondria for energy production
  • Sperm tail provides motility ( movement ability) for sperm cell
  • Sperm cell is 5-6 micrometers long and 2-3 micrometers wide
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Normal sperm morphology

sperm morphology

Normal sperm morphology is accepted between 4-14%. Every male may have abnormal sperm cells in their semen sample and at least 4% of normal morphology sperm cells may be enough for fertilization.

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Sperm neck

Sperm neck is the short, narrow part between sperm head and mid piece at the beginning of the mithocondrial helix. Sperm neck has mithocondria like mid-piece  but only 2-3. Sperm neck has centrosomes which has an important function for fertilization of egg and embryo development. We can say that centrosome formes sperm cell’s brain and nervous system with its microtubules.

Centrosome becomes active just after sperm enters the egg, divided into two pieces and formes strands. Chromosomes that come from mother and father are attached to these strands and connect each other. Then egg starts to split and multiply by help of  centrosome strands.

Egg centrosome disappear just after fertilization and only sperm centrosome remains, this means centrosomes come from father. Embryo can’t grow if there is a problem in sperm centrosome. Sperm centrosome problems cause unsuccessful IVF treatment ( in vitro fertilization – test tube baby process). Sperm centrosome problems may be diagnosed by determining sperm neck deformity  in sperm morphology examination ( semen analysis).