| | | | | | The Medical Algorithms Project |
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| Chapter : | ch16. Male Genital System | Section : | Semen Analysis | | WHO Classification of Sperm Morphology | | Copyright (c) 2006-2007, Institute for Algorithmic Medicine, Houston, TX, USA. All rights reserved. |
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Overview :
The World Health Organization (WHO) has published criteria
for evaluating sperm morphology and identifying abnormal forms.
Parameters:
(1) head shape
(2) head size
(3) acrosome size
(4) head – others
(5) neck and midpiece
(6) tail
|
Parameter |
Normal
Features |
|
shape |
oval with smooth margin |
|
length |
4 – 5 microns |
|
width |
2.5 – 3.5 microns |
|
ratio of length to width |
1.5 – 1.75 |
|
acrosome (distal clear zone) |
40- 70% of head |
|
cytoplasmic droplets |
small (see below) |
|
width neck and midpoint |
neck just under 1 micron, straight |
|
neck insertion |
one of the long axial tips of the head |
|
tail |
straight, about 45 microns in
length |
Number of heads:
(1) double
Head shape:
(1) round
(2) tapered
(3) amorphous
(4) piriform (pear shaped)
Head size:
(1) small
(2) large
Acrosome:
(1) absent
(2) < 40%
(3) > 70%
(4) irregular
(5) vacuolated
Neck and midpoint:
(1) thin
(2) thick
(3) irregular debris
(4) large
cytoplasmic droplets (the WHO manual says normal is < 50% of head diameter
but says abnormal is > 33% in Figure 2.8, page 20)
(5) eccentric insertion into head
(6) bent
(7) short
Tail:
(1) double
(2) coiled
(3) bent
(4) short
| | References: | |
Kruger TF,
Acosta AA, et al. Predictive value of abnormal sperm morphology in vitro
fertilization. Fertility and Sterility. 1988; 49: 112-117. (Figure 1 and text,
page 113).
World
Health Organization. WHO Laboratory Manual for the Examination of Human Semen
and Sperm-Cervical Mucus Interaction, Fourth Edition. Cambridge University
Press. 1999. pages 19-21
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