Oocyte grading

1. OOCYTE GRADING AND
QUALITY ASSESMENT
Dr Mrunal Gaikwad
Guide: Dr Chaitanya Shembekar sir

3.  Ideal mature human oocyte(MII), based on
morphological characteristics, should have a
homogenous cytoplasm, a single polar body, an
appropriate zona pellucida thickness and proper
perivitelline space.
 During ART cycles, OS allows maturation of
oocytes which are destined to be atretic and hence
compromise oocyte quality.
 The developmental competance depends on
nuclear and cytoplasmic maturation and its
synchronisation.
 The dysmorphic oocytes which usually fail to get
fertilized by IVF may get fertilized by ICSI.

5. COMPONENTS OF NORMAL OOCYTE
BEFORE
DENUDATION
AFTER
DENUDATION

6. OOCYTE CUMULUS COMPLEX
According to Lin and colleagues, 5 groups of OCCs
based on morphology of :
 Oocyte cytoplasm
 Cumulus mass
 Corona cells
 Membrane granulosa cells
SUN BURST
APPEARANCE

7. IMMEDIATELY AFTER PICKUP

8. OCC GRADING
1.MATURE OCC
 Expanded cumulus
 Radiant corona
 Clear cytoplasm
 1st polar body seen

9. 2. APPROXIMATELY MATURE OCC
 Expanded cumulus
 Slightly compact
corona

10. 3. IMMATURE OCC
 Adherent compact layer of
corona
 Ooplasm with germinal
vesicle
 First polar body not seen

11. 4. POST MATURE OCC
 Expanded cumulus with
clumps
 Irregular incomplete
corona
 Dark and granular
cytoplasm

12. 5. ATRETIC OOCYTE CORONA
 Clumped very irregular
corona
 Dark and misshapen
cytoplasm

13. OOCYTES
A. Morphological assessment
I. Size and shape
a. Giant oocytes
b. Dysmorphic oocytes
c. Oval oocytes
d. Conjoined oocytes
e. Atretic oocytes
II. Intracytoplasmic anomalies
a. Granulations
b. Inclusion and refractile bodies
c. Vacuoles
d. SER clusters / SER discs
e. Dark cytoplasm
III. Extra-cytoplasmic anomalies
a. First polar body morphology
b. Perivitelline space and granularity
c. Zona pellucida
B. Oocyte ageing
C. Viscosity of ooplasm and resistance of cell membrane by ICSI pipette

14. MORPHOLOGICAL ASSESSMENT
SIZE AND SHAPE

18. II. INTRACYTOPLASMIC GRANULATIONS
 These granulations are result of organelle clustering and
associated with lower implantation potential
 Can be
1. Diffuse cytoplasmic granularity: 50% of ooctyes are
aneuploid and associated with decreased cryosurvival
2. Centrally located cytoplasmic granular area: presence
of blood clots in COC are associated with dense
central granulation of oocytes, negative effect on
fertilization and blastocyst rates
3. Diffuse peripheral granulations: ass with compromised
pronuclear morphology

21. INCLUSIONS AND REFRACTILE BODIES
 Inclusions might get stuck in the injection pipette
while aspirating ooplasm during ICSI.
 So aspiration should be done away from inclusions
 Refractile bodies can be occasionally seen.
Morphological variations with no prognostic
significance.

23. VACUOLES
 These are fluid filled structures, easily appreciated
 A vacuole of > 14 μ diameter results in significantly
decreased – fertilization rates by displacing MII
spindle from its polar position
-cryosurvival
o Three types of vacuoles
o 1. present at oocyte collection, which develop
during maturation
o 2. Artificially created by ICSI (day 1)
o 3. Vacuoles accompanied with developmental
arrest(day 4)

25. SER CLUSTERS / DISCS
 It appears like translucent disc like structure, which
has to be differentiated from a vacuole.
 It is strongly recommended not to inseminate
oocytes with SER discs and to re-examine all
sibling oocytes before inseminating
 Ass with poor obstetric outcome
 Studies have shown ass with imprinting disorders
such as Beckwith-Wiedemann syndrome.

27. DARK CYTOPLASM
 These have 83% lower
chances of forming
good quality embryo
and resulting embryos
have decreased
implantation rate
 However studies have
shown no difference in
lab and clinical
outcome.

28. II. EXTRACYTOPLASMIC- FIRST POLAR BODY
MORPHOLOGY

29. PERIVITELLINE SPACE
 Space between oolemma and ZP
 Normally the gap is invisible through out the contact
area except near polar body
1. Large PVS- seen in one third of all ova. Might be a
result of overmature eggs or large PB.
2. Granulated PVS- can be physiological or exposure
to higher doses of HMG
However any of these does not affect the fertilization
rate, but a note should be made of an exceptionally
large PVS

31. ZONA PELLUCIDA MORPHOLOGY
 Zona Pellucida is dynamic multifunctional structure
at different stages of embryogenesis.
 At oocyte stage: prevents polyspermy
 At cleavage stage: selective permeability to
maintain optimum concentration of nutrients
 At blastocyst stage: thins out to facilitate hatching
 Normal Thickness:16-18 micrometer

32. ZONA PELLUCIDA
1. Variation in thickness

33. 2. Irregular ZP

34. 3. Duplication/ tears of inner layer

35. 4. Dark ZP

36. OOCYTES AGEING
 This may be due to in vivo
or in vitro acquired cellular,
biochemical and
morphological changes
leading to reduced FR,
polyspermy,
parthenogenesis,
chromosomal disorders
and poor developmental
potential
 Noticeable features- dark
cytoplasm, dark ZP, large
PVS with granularity

37. THE RESPONSE OF THE OOCYTE PLASMA
MEMBRANE TO THE ICSI PIPETTE
 ‘normal break’ oocytes- oocytes in which some
suction is required to rupture the plasma membrane
 ‘easy break’ oocytes- oocytes in which the plasma
membrane breaks immediately upon the pressure
of the ICSI pipette- lower level of fertilization,
degeneration and abnormal fertilization
 ‘difficult break’ oocyte patterns- oocytes in which
excessive suction is required to rupture the oocyte
plasma membrane.
An oocyte score for use in assisted reproduction 2007 Wilding et al

39. THANK YOU