This document discusses sperm density gradients, which is a technique used in semen analysis. It involves layering solutions of different densities on top of each other to separate sperm by weight and mobility. During centrifugation, the most motile and normally shaped sperm pass through the layers and settle at the bottom of the tube, separated from non-viable sperm and other materials. This density gradient method is useful for selecting sperm when semen quality is poor due to low count, abnormal shapes, or lack of movement. It isolates healthy sperm for procedures like in vitro fertilization.

1. SPERM DENSITY GRADIENTS
By: Prachi Naik

2. WHAT IS SEMEN ANALYSIS
• Semen Analysis is an important diagnostic tool for the evaluation of male
fertility, by examining the male semen and the sperms present within.
• This investigation is carried out according to WHO guidelines, focusing more
on the concentration, morphology and motility of the Sperm.

3. TYPES OF SEMEN ANALYSIS
1. Simple wash
2. Swim up
3. Density gradient

4. WHO PARAMETER FOR SEMEN ANALYSIS
WHO 2010 WHO 2021
Semen volume (mL) 1.5 (1.4–1.7) 1.4 (1.3–1.5)
Total sperm number (106
per
ejaculate)
39 (33–46) 39 (35–40)
Total motility (%) 40 (38–42) 42 (40–43)
Progressive motility (%) 32 (31–34) 30 (29–31)
Non progressive motility (%) 1 1 (1–1)
Immotile sperm (%) 22 20 (19–20)
Vitality (%) 58 (55–63) 54 (50–56)
Normal forms (%) 4 (3–4) 4 (3.9–4)

5. WHAT IS DENSITY GRADIENT
• This is the preferred technique to select the greater number of motile
spermatozoa in cases of severe oligozoospermia, teratozoospermia or
asthenozoospermia.
• In this method, good quality sperms can be separated from dead sperms,
leukocytes and the other components of the seminal plasma by a density
discontinuous gradient.
• Cells with different density and motility can be selected during the
centrifugation by the colloidal silica coated with silane of the gradient; the
sperms with high motility and good morphology are at the bottom of the tube,
finally free from dead spermatozoa, leukocytes, bacteria and debris.

6. PROCEDURE OF DENSITY GRADIENT