Follicular dynamics in cattleandbuffalo.ppt

Follicular dynamics is the development of antral follicles during an estrous cycle. It can be an indicator for reproductive management in livestock, and can involve different features depending on the species:
Bovine
The estrous cycle has two to three growth waves, and only the last wave results in ovulation. The dominant follicle transitions from follicle-stimulating hormone (FSH) to luteinizing hormone (LH).
Gir cattle
Has a higher number of follicular waves during the estrous cycle, but the dominant follicles from intermediate waves don't persist as long.

1. FOLLICULAR DYNAMICS IN CATTLE AND BUFFALOES
Priya Ranjan Kumar

2. Follicle?
Primordial, growing and antral follicle
(Erickson, 1966)

3. FATE OF OVARIAN FOLLICLES
Non growing
Growing
30-50 Ova
Follicular dynamics

4. Recruitment
Selection
Dominance
Emergence
Deviation
Stages of follicular dynamics

5. Recruitment
Non growing pool Growing pool
Gonadotrophins
Signal(s)
Growth Factors (???)
Positive (e.g. Kit Ligand, Insulin, LIF, FGF2, BMP4, BMP7 and
GDF9) and negative (e.g. AMH and CXCL12) regulators of the
primordial to primary follicle transition

6. Numbers of follicles recruited
CATTLE 24
(50% Atresia)
BUFFALOES 15
(67% Atresia)

7. Emergence
Sudden growth of recruited follicles
Cattle 1-4 waves/cycle
Buffalo 1-3 waves/cycle
3-waves common in Egyptian
buffaloes
Tendency for repeatability
Positive regulators FSH, Activins, EGF, bFGF

8. Time of Emergence of waves
CATTLE BUFFALOES
1
st
waveDay 0 Day 1
2
nd
waveDay 9 or 10 (2-wave)
Day 8 or 9 (3-wave)
Day 10.8 (2-wave)
Day 9.3 (3-wave)
3
rd
waveDay 15 or 16 Day 16.8

9. Selection
Only one follicle selected
{Most effective mechanism in monovular species}
FSH(-)
Selection LH receptors (+)
Free IGF-I Concentration(+)
Selectedfollicle
FeedbackInhibitionofFSH
(E2andInhibin)
Starvationofotherfollicles

10. Deviation
Differential change in growth rates between the largest
and next largest follicle
Deviation Around 2.6 days after wave emergence
B. taurus cattle (8.5 and 7.2 mm, respectively)
Zebu cattle (6.2 and 5.8 mm, respectively)
Buffaloes (7.2 and 6.4 mm, respectively)
Very similar diameter

11. Deviation
Deviated follicle releases increased amount of both
estradiol and inhibin
Activinincreases the estradiol secretion
LH stimulates production of IGF-I
IGF act synergistically with gonadotrophins
Cont…

12. Dominance
Capable of ovulation after luteal regression
Can be observed by:
Morphologically: Size (≥10 mm)
Physiologically: Vascularity and Granulose cell
LH receptors
Endocrinologically: Follicular fluid estradiol and
inhibin
Dominance is maintained by negative feedback effects

13. Endocrine Regulation

14. Endocrine Regulation

15. Endocrine Regulation: Growth hormone
Primordial
Primary
Expression of conexin-43
Secondary
Increased expression of conexin-43
Antral
Steroidogenesis by GC
Oocyte maturation
Expansion of the cumulus cells
Preovulatory

16. Local regulation
Inhibins Activins Follistatin
FSHsuppressive
action
Induction of FSH
receptors
Increases
aromatase activity
Regulate expression
of follistatin
Neutralize
biological activity
of activins
Differentiation of
granulosa cells

17. Local regulation
IGFBP
IGFs
IGFBP IGFs+
PAPP -A
Growth and maturation Apoptosis
+-
IGF System