Male gamete:
Spermatozoon (sperm,
sperm cells)
A mature spermatozoon
Objectives
• You should be able to describe a mature male
gamete (spermatozoon)
• You should be able to understand some
clinical significance of the sperm
A mature spermatozoon
Anatomic parts of spermatozoon
•
•
•
•
Head
Neck
Middle piece
tail
Characteristics of the sperm
• Microscopic
• Elongated, like a tadpole (about
60 µm)
• Highly motile (about 3
mm/min)
• Highly differentiated
• Haploid
– (23 chromosomes)
• Viable for average of 48 hours
in the female tract
Head of a spermatozoon
• The head of a spermatozoon is the anterior
ovoid or piriform end.
• About 4 µm long and 3 µm wide at its
widest part
• Contains a densely-parked nucleus, and the
acrosomal cap
• Acrosomal cap overlies anterior ⅔ of the
nucleus
Head of spermatozoon
• The head of a
spermatozoon is the
anterior ovoid or piriform
end.
• About 4 µm long and 3
µm wide at its widest part
• Contains a denselyparked nucleus, and the
acrosomal cap
• Acrosomal cap overlies
anterior ⅔ of the nucleus
• These include (some lysosomal)
enzymes:
– Acrosin (a proteinase)
– Hyaluronidase (hydrolysis of
hyaluronic acid)
– Neuraminidase (sialidase, a
glycohydrolase; hydrolysis of
glycosides)
– Arylsulphatase (hydrolysis of sulphate
moiety of
glycoproteins)
• The acrosomal cap is derived from
the Golgi apparatus.
• external to nucleus and acrosome is
the cell membrane
• No cytoplasm intervenes between
them
Contents of
acrosome
Sperm nucleus
• Nature: highly
condensed/compact
(nuclear proteins in
sperm are largely
protamines)
• Location: head of sperm
(behind acrosome)
• Forms male pronucleus
at fertilization
• Is haploid (has 23
chromosomes)
Neck of the sperm
• Is a small constriction
• Position: just caudal
to the head
• Length: about 0.3 µm
• Contains centrioles
proximally and basal
body distally
• Also contains a little
amount of cytoplasm
Middle piece of sperm
• Location: just distal to neck
• Length: 7 µm long
(cylindrical portion)
• Structure: made of the
central axoneme, and spiral
sheath of mitochondria
Middle piece of sperm
• Axoneme:
• consists of a central pair of
microtubules surrounded by
nine pairs of microtubules.
• Dynein and radial spokes
(protein complexes) are
associated with these
microtubules
• mitochondrial sheath
surrounds axoneme.
Mitochondria are arranged in a
helical pattern around axoneme
• Mitochondria generate ATP for
sperm motility
Tail of spermatozoon
• caudal part of a spermatozoon
• Long tapering process :
• is about 40 µm long &
• 0.5 µm wide
• resembles a flagellum.
• Its core is has the axoneme
(bundle of microtubules)
• plasma membrane envelops the tail
externally
• repeated movement of the tail
produces sperm motility (of 3
mm/minute)
THE OVUM
MORPHOLOGY
HUMAN OVUM (200 µM)
CHARACTERISTICS
• Rounded
• Large
• 200 µm;
• Size of pin head
• Immotile
• Viable for about 24
hours post-ovulation
• Rich in nutritive yolk
– Lecithin (lipid)
– Isolecithal; lecithin
being evenly distributed
The gametes
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•
•
•
•
•
•
•
•
•
•
•
1 =nucleolus
2 =nucleus
3 =zona pellucida
4 =head
5 =acrosome
6 =centriole
7 =mitochondrion
8 =tail
9 =middle piece
10 =neck
11 =corona radiata
12 =cytoplasm
OVUM
SPERM
PARTS OF THE OVUM
• Nucleus (germinal vesicle)
– haploid (23 chromosomes)
• Nucleolus (germinal spot)
• Cytoplasm (vitellus, yolk, ooplasm)
– Formative yolk (= normal cytoplasm; has organelles)
– Nutritive yolk (=deutoplasm; has lecithin; isolecithal)
• Cortical granules
– Contain enzymes required for
zona reaction and cortical reaction
• Cell (plasma) membrane
• Zona pellucida
– of glycoprotein
Miss. Egg , I miss
you very much!
Mr. Sperm , I
miss you very
much too !
Study questions
1. Give a brief definition of embryology
2. List and define specific stages in
human embryogenesis
3. Draw, label and describe a mature
human spermatozoon
4. Draw, label and describe a mature
human ovum
5. Write a short not on the clinical
correlates of the human gametes