The document discusses the molecular mechanisms of cervical ripening in ruminants. It describes the stages of cervical remodeling as gradual cervical softening, final cervical ripening, and cervical dilatation and repair. Key factors that regulate cervical remodeling include hormones like progesterone and estrogen, relaxin, prostaglandins, proteoglycans, and matrix metalloproteinases. Cervical remodeling involves changes to the extracellular matrix, such as collagen breakdown, increased proteoglycans and hyaluronic acid, mediated by hormonal and inflammatory signals.

1. WELCOME TO MINOR CREDIT SEMINAR

2. Molecular Mechanism Of Cervical Ripening in
Ruminants
Dr Rouf Rashid
ROLL NO: M-5606
MVSC scholar
Animal Reproducion division

3.  Introduction
 Stages of cervical remodelling
 Factors involved in cervical remodelling
 Role of MMPs
 Conclusion
Overview

4. predominantly
of connective
tissue
small amounts of
smooth muscle
tissue presents
cervix is a
fibrous organ
thick wall and
constricted
lumen
(Leppert 1995).
Introduction

5.  Cervix also having same 3 layers
stromal layer more predominant
Mucosal
layer:
consisting of
epithelium
and
underlying
stroma Serosal layer:
outer most
Muscular
layer: consist
of
inner circular
& outer
longitudinal
HISTOLOGY OF FEMALE
GENITAL TRACT

6. Cross sectional view of the bovine
cervix
 3: Cervical lumen with
protruding annular rings
 4: Epithelial and superficial
stromal layer
 5: Deep stromal layer
 6:Outer muscular layer
 7: Serosa

7.  Connective tissue
Ground substance
 Proteoglycan
• Hyalurunic acid,
• Chondroitin-4,6
sulfate,
• Dermatan sulfate,
• Heparan sulfate,&
• Keratan sulfate
 Glycosaminoglycans
 Fibrillar collagen
 Matricellular
proteins
Fibrous
constituents-
 Collagen
 Elastin
 Reticulin
Cellular
elements-
 Mast cells
 Fibroblasts
 Wandering cells
Cervical stroma

8. I. Gradual ripening- last months ( cervical softening )
II. Final ripening- parturition ( cervical ripening and cervical
dilatation)
 Gradual cervical ripening-
 Clinically - palpable softening
 Biochemically –
water imbibition,
separation of collagen bundles
collagen denaturation
 Collagen denaturation - cervical MMPs (van Engelen2008)
Cervical Remodelling- 2 stages

9. Final cervical ripening
 Just before and during cervical dilatation.
 Collagen fibrils are denatured and digested by
matrix metallo proteinases as a part of
inflammatory cascade

10. Cervical
softening
Cervical
ripening
Cervical
dilatation
Cervical
repair

11.  First measurable increase in tissue distensibility when
compared with non pregnant cervix ( Read et al . 2007 )
 High P4/E2 ratio
 Changes in the ratio of type 1 to type 3 collagen , alteration in
post transcriptional processing of collagen monomers and
assembly of collagen monomers into collagen fibrils can affect
collagen structure and its mechanical strength (Lieu et al. 1997 )
 Increase in collagen solubility with no change in total collagen
content
Cervical softening

12.  Evidence of downregulation of specific steps in the collagen
processing pathway icclude folowing
(a) Decline in cervical expression and activity of lysyl
hydroxylase(LH) and lysyl oxidase (LOX) respectively in early
pregnancy ( Akins et al . 2011 )

13. (b) subsequent decline in collagen containing the stronger
pyridinoline cross links in second half of gestation
(c) Collagen turnover appears upregulated during the pregnancy
but the total collagen content remains constant throughout
pregnancy
(d) MMP activity not reported in this phase
(e) Constant breakdown of collagen to maintain steady collagen
levels and facilitate replacement of mature by poorly cross
linked collagen fibre

14. Matricellular Proteins

 Thrombospondin 2 (thbs2) and tenascin 2 (Tns) proteins are
down regulated in early gestation and remain low untill just
before birth ( Akins et al . 2011 )
 They have a role in cervical softening , through the formation
of appropriately assembled collagen fibril and regulate the
activity of MMPs , and is a inhibitor of angiogenesis in various
tissues ( Kokenyesi et al . 2004 )

15.  Tenascin is upregulated during tissue injury ( postpartum)
through proinflammatory and fibrotic responses
 Thus replacement of mature cross linked collagen with
collagen harbouring reduced cross links with decline in the
THBS2 and TNC in the cervix is a key in modulating collagen
architecture within ECM during softening

16. Cervical epithelial

 provide immunoprotection and maintenance of a barrier which
protect stromal compartment
 Trefoil factor 1 (TFF1) is a gastric secreted peptide , protection
and restitution of cervical mocosal epithelia ( Read et al . 2007 )
 Serine protease inhibitor Kazal type 5 (SPINK5) functions to
prevent degredation of desmoglein involved in barrier
formation

17.  They are of short duration and very rapid , overlapping each
other
 Low P4/E2 ratio present
 Maximum loss of tissue compliance and structural integrity
 Decline in collagen content ( Rajabi et al. 1991 )
Cervical ripening and dilatation

18. 
 Progressive increase in collagen fibril diametre in the cervix
from early to late gestation along with increased spacing
between the fibrils ( Akins et al.2011 )
 Increased synthesis of glycosaminoglycan and hyaluronan ( HA;
Straach et al .2005 )

19.  Proliferation of mucosal epithelia which is dependent on
actions of Relaxin and Estrogen ( Lee et al . 2005 )
 Epithelium become laden with mucus secreting vacuoles
important in immune surveillance and lubrication
 Epithelium also expresses steroid 5 α reductase type 1 (SRD5A1)
important in local progesterone metabolism ( Mahendroo et al .
1999 )

20. Loss of p4 function along with increased metabolosim facilitate
transition to ripening phase
 During ripening the barrier properties of mucosal epithelia ,
hydration , cell to cell communications are regulated by
increased expresion of tight junction proteins (claudin 1 and 2) ,
aquaporins , gap junction proteins ( connexin 26 and 43 ) , and
desmogleins ( Gonzalez et al . 2009 )
 Immune cells play a role in ECM remodelling via activation of
proinflammatory signals and the release of MMPs that
breakdown collagen ( Liggins 2006 )

21.  During ripening there is an influx of monocytes into the cervix
 Physiological ripening is not mediated by an inflammatory
cascade
 Recent studies suggest that eosinophils promote the
differentiation of the monocytes into alternatively activated
macrophages (M2) during postpartum repair

22.  Expression of epithelial specific genes such as Desmogleins and
Keratin 16 as well as inflamatory associated genes and genes
involved in ECM synthesis , processing and repair
 In contrast to ripening phase , myeloid derived immune cells
play an important role in this phase of remodelling
Postpartum cervical repair

23.  Monocytes entered the cervix during ripening phase are
differentiated to macrophages and polarised to both M1 and M2
phenotypes with onset of labour or postpartum
 Matrix debris clear up
 Increased activity of HA metabolising enzyme , hyaluronidase 1,
and subsequent increase in low MW HA (Akgul et al .2012 )

24. Cervical
ripening
Enzymatic
degradation
Hormonal
regulation
Increase in
proteoglycan
Inflammatory
mechanism

25. ↓P4
↑E2
↑RELAXIN
 PROSTAGLANDIN
Hormonal regulation

26. Progesterone:
P4 or con. of P4 receptors cervical ripening
Activation of NFκB in turn
Inhibit P4 receptor activity TIMP’S
cervical ripening

27. Relaxin
 Relaxin stimulates MMPs expression on cervix.
promotes both epithelial cells and stromal cells accumulation
By stimulating cell proliferation& inhibiting apoptosis
Relaxin act on fibroblastic cell receptors
Relese of MMPs causes collagenolysis( TIMP’S)

28. Mechanism of relaxin induced hydration in cervix not understood.
 But, Enlargement of cervial arteries my be a factor and it stimulate
procollagenase and also reduces TIMP’s
 Relaxin may act cervix through stimulation of PG synthesis
Prostaglandin
 Prostaglandin have important role in cervical ripening
PGE2 → Chemokine (IL8) → Neutrophils → degranulation → MMPs
→ collagen degradation
A.-R. Fuchs et al. / Prostaglandins & other Lipid Mediators 70 (2002) 119–129

29. Estrogen
 Estrogen receptors are expressed in cervix at term.
 sensory neurons have also been implicated in cervical
ripening.
 substance P release from neurons terminating in the
cervix and spinal cord peaks before parturition.
 mRNA levels of calcitonin gene related peptide,which
colocalizes with substance P increases at term and its
expression increased by estrogen

30. Trends in Endocrinology and Metabolism 21 (2010) 353–361

31.  Withdrawal of P4 + Proinflam stimulus
Act NFkB (Schmitz et al. 2004)
GAG
CYTOKINES-
CERVIX
MACROPHAGE
-FETAL
iNOs COX2
NO
PG
IL 8
neutrophils
IL 1,TNFα
IL 8
FIBROBLAST
MMPs
NEUTROPHIL
Inflammatory mechanism

32.  Matrix Metalloproteinase (MMPs) play important role in
cervical ripening
 MMPs secreted by
1.Stromal cells
2.Fibroblasts
3.Smooth muscle cells
4.Inflammatory cells invading
cervix(final)
Enzymatic degradation

33.  Cervical total GAG content with progression of pregnancy &
accompanied by dramatic changes in composition.
Function of proteoglycans :
1.Decorin modulate the collagen fibril & spacing and access to
proteases.
2. Versican It influences structural disorganization of the ECM
Hyaluronan synthase 2 expression & subsequent in Hyaluronic
acid (HA) is a distinct feature of cervical ripening.
Proteoglycans
(Mahendroo,et al 1996) Trends in Endocrinology and Metabolism 21 (2010) 353–361

34.  In the first step (during ripening), hyaluronic acid & its association
with proteoglycan ( versican) is required
 Just prior to or during the onset of labor
The expression of Hyaluronidase & ADAMTS1 leads to the
disruption of HA–versican cross links going to breakdown in to HA
and versican, respectively
 The breakdown to smaller size products might be a second step in
the loss of cervical tensile strength and integrity required for cervical
dilation and birth
(Mahendroo,et al 1996) Trends in Endocrinology and Metabolism 21 (2010) 353–361

35. (Mahendroo,et al 1996) Trends in Endocrinology and Metabolism 21 (2010) 353–361

36. (Mahendroo et al. 1999). Trends in Endocrinology and Metabolism 21 (2010) 353–361

37. conclusion
 Incremental and progressisive changes in the ECM occur
in a P4 rich environment during softening with further
rapid and more aggressive changes to the ECM upon the
loss of P4 function during cervical ripening and dilatation
 To complete loop of remodelling and allow subsequent
pregnancies, proinflammatory and immunosupressive
processes modulate tissue repair postpartum

38.  Dynamic, cumulative changes in the crvical ECM are initiated
early in the pregnancy and culminate in the formation of highly
disorganised ECM of unique composition that allows for the
loss of tissue integrity resulting in cervical opening during
parturation