Follicular dynamics

1. FOLLICULAR DYNAMICS

2. OVARY - FUNCTIONS AND STRUCTURE
Two major functions of ovary are:
1. Gametogenesis – Cyclic production of fertilizable
ova.
2. Steroidogenesis – production of steroid hormones

3. Schematic diagram of an ovary showing the sequence of
events in the origin, growth, and ovulation of follicles and
formation and regression of the corpus luteum.

5. FOLLICULOGENESIS
Folliculogenesis is the process of forming mature follicles
capable of ovulation from the pool of growing primordial
follicles in the ovary.

7. •One or more cuboidal granulosa cells
that are arranged in a single layer
surrounding the oocyte.
• Simultaneous with the shape change
and mitotic activities that accompany
recruitment, the cuboidal granulosa cells
begin to express FSH receptors.
• Granulosa-derived activin may play an
important role in the expression of FSH
receptor by autocrine/paracrine
mechanisms.
1. Primary Follicle.

8. • A secondary follicle is a preantral follicle with 2
to 10 layers of cuboidal or low columnar cells that
form a stratified epithelium.
•Oocyte derived growth factor, called growth
differentiation factor-9 (GDF-9) is obligatory for
folliculogenesis after the primary stage as it is an
obligatory mitogen for granulosa cells.
•Oocyte plays a pivotal role in regulating
folliculogenesis through its ability to produce
novel regulatory ligands (e.g. GDF-9), which are
crucial for folliculogenesis.
2. Secondary Follicle.

9. Five distinct structural units:
1. A fully grown oocyte surrounded
by a zona pellucida
2. Six to nine layers of granulosa
cells,
3. Basal lamina,
4. Theca interna,
5. Theca externa.
The first indication of the onset of
tertiary follicle development is
the appearance of a cavity in
the granulosa cells - antrum
3. TIRTIARY
FOLLICLE.

10. A graafian follicle can be defined
structurally as a heterogeneous family
of relatively large follicles (0.4 to 23
mm) characterized by a cavity or antrum
containing a fluid called follicular fluid or
liquor folliculi.
The characteristic structural unit of all
graafian follicle is the antrum.
4. Graafian /Antral Follicle

14. FOLLICLE

15. FOLLICULAR WAVE
 In 1984 , the first studies using ultrasound revealed that
follicular growth occurs in waves, each wave culminating
with formation of a large follicle.
Factors influncing the number of waves per estrous cycle
 Dietary intake
 Age
 Parity
 Lactational status.
In general, primiparous and multiparous lactating dairy cows
exhibit more two-wave cycles, whereas nulliparous dairy
heifers tend to exhibit more three wave cycles.

16. FOLLICULAR WAVE…
 Steps in follicular wave:
1. Recruitment
2. Dominance
3. Ovlution/atresia

17. A follicular wave begins with emergence of a group or
cohort of small antral follicles just before the day of
ovulation
During the next several days, one of the follicles in this
cohort continues to grow and becomes dominant,
thereby suppressing emergence of a new follicular wave.
Subordinate follicles eventually undergo atresia
A second wave of growth emerges on approximately
Day 10 after ovulation
Three-wave cycles, an additional wave emerges at Day
16 after ovulation

19. Follicular dynamics in a 2-wave cycle

21. Follicular dynamics in a 3-wave cycle

22. DISCUSSION