study of structure of gametes in some representative cases

1. STUDY OF STRUCTURE OF GAMETES IN
SOME REPRESENTATIVE CASES
Presented By:
Humna Nadeem

2.  The egg or ovum is a spherical cell about 1.6 mm
in diameter.
 It is covered by albumen layer and vitelline
membrane.
 One half of its surface is deep blackish brown in
color due to presence of a superficial layer of
pigment.
 The other half is lighter in color and it is in this
half that bulk of yolk is aggregated
(telolecithal).
 The large egg nucleus lies in the pigmented half
which is, therefore, the animal hemisphere of
the egg.
 The dark area is known as vegetative pole.

4.  The sperm is microscopic, thread-like, motile body
having typical head, middle piece and tail.
 The head is elongated having a large haploid
nucleus capped with conical acrosome.
 The middle piece has centriole and mitochondria.
 The middle piece is followed by a long tail.
 The tail bears an axial filament.
 The sperm is functionally mature and is capable
of fertilizing the ovum.
 The sperms are produced in the seminiferous
tubules of the testes as a result of
spermatogenesis.

6.  It is a diploid cell.
 In a fertilized egg, rotation of orientation
occurs.
 Due to rotation of orientation, the
ooplasm differentiates into upper
pigmented half or animal hemisphere,
light black-colored crescent-shaped grey
crescent and whitish yolky lower part or
vegetal hemisphere.
 It is an activated cell, ready to undergo
process of cleavage.

9. Classification of egg based on distribution of yolk

11. Macrolecithal egg
zebra fish

12. Microlecithal egg
Human