Advanced Reproduction Physiology (Part 3) - PowerPoint PPT Presentation


PPT – Advanced Reproduction Physiology (Part 3) PowerPoint presentation | free to download - id: 4f4a24-ODMyN


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation

Advanced Reproduction Physiology (Part 3)


Isfahan University of Technology College of Agriculture, Department of Animal Science Advanced Reproduction Physiology (Part 3) Prepared by: A. Riasi – PowerPoint PPT presentation

Number of Views:262
Avg rating:3.0/5.0
Slides: 77
Provided by: Ahmed94


Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Advanced Reproduction Physiology (Part 3)

Advanced Reproduction Physiology (Part 3)
  • Isfahan University of Technology
  • College of Agriculture, Department of Animal

Prepared by A. Riasi http//
Physiology of Pregnancy and Embryo Development
Spermatozoa in female tract
  • In natural mating semen are introduced in
  • Vagina
  • Cervix
  • Within the female tract spermatozoa are lost by
  • Phagocytosis by neutrophils
  • Physical barrier including the cervix

Spermatozoa in female tract
  • Two stages for spermatozoa transport
  • Rapid transport
  • Oxytocin secretion
  • Prostaglandins
  • Sustained transport

Spermatozoa in female tract
  • Factors may affect spermatozoa transport in
  • Sperm motility
  • Physicochemical change in cervix secretions

Spermatozoa in female tract
Spermatozoa in female tract
  • Sperm capacitation
  • Chemical changes
  • Remove decapacitation factors
  • Remove cholesterol
  • Membrane ions changes
  • Physical and morphological changes

Spermatozoa in female tract
  • Higher levels of FPP prevent capacitation
  • FPP is found in the seminal fluid and comes into
    contact with the spermatozoa upon ejaculation.
  • It has a synergistic stimulatory effect with
    adenosine that increases adenylyl cyclase
    activity in the sperm.

Spermatozoa in female tract
  • Other chemical changes
  • Removal of cholestrol and non-covalently bound
    epididymal/seminal glycoproteins is important.
  • The result is an increased permeability of sperm
    to Ca2, HCO3- and K
  • An influx of Ca2 produces increased
    intracellular cAMP levels.

Spermatozoa in female tract
  • Altering the lipid composition of sperm plasma
    membranes affects
  • The ability of sperm to capacitate
  • Acrosomal reaction
  • Respond to cryopreservation.

Spermatozoa in female tract
  • High intracellular concentrations of Ca2, HCO3-
    and K are required for
  • Acrosome reaction
  • Fuse with the oocyte.

Spermatozoa in female tract
  • Physical and morphological changes

The oocyte moving in female tract
  • Oocyte is transported by cilia of oviduct.
  • Smooth muscles of oviduct adjust the time of
    oocyte transportation.
  • The mature egg can only survive for about 6
    hours, so the time of insemination is important.

Sperm penetration
  • A series of events
  • First step acrosome reaction
  • After the reaction, the vesicles are sloughed,
    leaving the inner acrosomal membrane and the
    equatorial segment intact.

Sperm penetration
  • A spermatozoon has to penetrate four layers
    before it fertilizes the oocyte

Sperm penetration
Sperm penetration
Sperm penetration
Sperm penetration
Sperm penetration
  • Three changes occur in the oocyte after
    penetration of vitelline membrane

  • Fertilization has two important genetic
  • The diploid chromosome number is restored (2n).
  • The genetic sex of the zygote is determined

Increase conception rate
  • Embryonic mortality in the initial seven days of
  • Fertilization failure
  • Genetic defects
  • Impaired embryonic development

Increase conception rate
  • Measuring embryonic mortality in weeks two and
    three of gestation is much more challenging.
  • This period coincides with the maternal
    recognition of pregnancy.

Increase conception rate
  • Successful establishment of pregnancy depends on
    a delicate balance between
  • Luteolytic mechanisms inherent to the endometrium
    at the end of diestrus.
  • Antiluteolytic mechanisms, orchestrated by the

Increase conception rate
  • Some strategies for increasing conception rate
  • Using TAI protocols
  • Stimulate growth and/or differentiation of the
    pre-ovulatory follicle
  • Stimulate CL growth rate
  • Increase plasma progesterone concentrations in
    the initial three weeks after insemination.

Increase conception rate
  • Decrease the effects of a dominant follicle
    during the critical period
  • Antiluteolytic stimulus provided by the conceptus
  • Decrease uterine luteolytic capacity

Increase conception rate
  • Reproductive physiologists had long searched to
    develop a synchronization program.
  • Ovsynch synchronizes AI at a fixed-time without
    the need for estrus detection.

Increase conception rate
  • Some factors may affect Ovsynch results
  • The stage of the estrous cycle
  • Cyclic status at the time that GnRH is
    administered (Bisinotto et al., 2010)

Increase conception rate
  • Researchers have modifed the original Ovsynch
    protocol to try to
  • Improve synchrony and fertility through
  • Altering the timing of AI in relation to
  • Testing the various injection intervals of the
    original protocol

Increase conception rate
  • TAI programs need day-to-day operation, so it may
    use for
  • Lactating dairy cows with little or no estrus
    detection at all
  • Voluntary Waiting Period (VWP)

Increase conception rate
  • Factors explaining the variation in conception
    rate to TAI among herds may include
  • The proportion of anovular cows
  • The follicular dynamics of individual cows
  • The ability of farm personnel to implement

Increase conception rate
  • Following this first report, numerous protocols
    have been proposed and routinely applied in high
    production dairy cows (Wiltbank et al., 2011).

Increase conception rate
  • Programming cows for first postpartum AI using
  • Use of presynch for programming lactating dairy
    cows to receive their first postpartum TAI can
    improve first service conception rate in a dairy

Increase conception rate
One possible hormone injection and TAI schedule
for the Presynch/Ovsynch protocol based on the
results of Moreira et al., 2000
Increase conception rate
  • In an assay, cycling cows conception rate was
    29 for Ovsynch and 43 for Presynch.
  • These protocols may presents low efficiency when
    applied in tropical condition.

Increase conception rate
  • Estradiol plus progesterone based protocol
  • Exogenous P4 and progestins has consequences
  • Suppresses LH release
  • Alters ovarian function
  • Suppresses estrus
  • Prevents ovulation

Increase conception rate
  • Novel studies introduced the use of E2 plus P4 to
    control follicular wave dynamics (Sá Filho et
    al., 2011)
  • Several studies found that E2 plus P4 treatment
    suppress the growing phase of the dominant
  • The interval from E2 treatment to follicular wave
    emergence seemed to depend on FSH resurgence
    (O'Rourke et al., 2000).

Increase conception rate
  • In E2 plus P4 protocols, a lower dose of E2 is
    normally given from 0 to 24 h after progestin
    removal to induce a synchronous LH surge (Hanlon
    et al., 1997 Lammoglia et al., 1998 Martínez et
    al., 2005 Sales et al., 2012).

Increase conception rate
  • Anestrous cows have insufficient pulsatile
    release of LH to support the final stages of
    ovarian follicular development and ovulation.
  • What we should do for anestrous cows?
  • The treatment with equine chorionic gonadotropin
    (eCG) may be effective.

Increase conception rate
  • eCG administration for anestrous or low BCS dairy
    cows has benefit effects (Souza et al., 2009
    Garcia-Ispierto et al., 2011).

Increase conception rate
  • Antiluteolytic strategies
  • Pharmacological
  • Mechanical
  • Nutritional
  • Management

Increase conception rate
  • Strategies to increase progesterone
  • Daily injection of progesterone
  • Using of progesterone releasing intravaginal
    device (PRID)
  • Inducing the formation of accessory corpora lutea
    by the ovulation of the first wave dominant

Increase conception rate
  • Effect of estrogen
  • Inskeep (2004) indicated that estrogen secretion
    from a large follicle from days 14 to 17 of
    pregnancy may negatively affect embryo survival.
  • This hormone has a central role in PGF production
    and luteolysis.

Increase conception rate
  • Some strategies for reducing estrogent
  • Absence of dominant follicles
  • Reduction of their steroidogenic capacity
  • Reduction of endometrial responsiveness to
    estradiol during the period of maternal
    recognition of pregnancy
  • Pharmacological approaches

Increase conception rate
  • Pharmacological strategies
  • The GnRH-hCG treatment
  • It induced an increase in plasma progesterone

Increase conception rate
  • Antiluteolytic strategies
  • Antiinflamatory drugs
  • Fat feeding
  • Bovine somatotropin (bST)

Increase conception rate
  • Synthesis of PGF results from a coordinated
    cascade of intracellular events.
  • A rate limiting step in this cascade is the
    conversion of arachidonic acid to
    prostaglandin-H2 (PGH).

Increase conception rate
  • The key enzyme is PTGS2 or COX-2.
  • The PGH is subsequently converted to PGF.
  • Guzeloglu et al. (2007) treated Holstein heifers
    with flunixin meglumine, a non-steroidal
    antiinflamatory drug which inhibits PTGS2
    activity, on days 15 and 16 after insemination.

Increase conception rate
  • Fat feeding influences several aspects of
    reproduction in cattle
  • (See review by Santos et al., 2008).

Increase conception rate
  • Feeding long chain fatty acids can modulate PGF
    production in the endometrium.
  • Effect of n-3 fatty acids (Mattos et al., 2003,
  • Effect of N-6 fatty acids (Pettit and
    Twagiramungu, 2004)
  • A summary of the effects of fatty acid feeding on
    cattle fertility reported by Santos et al. (2008).

Increase conception rate
  • Strategies for growth of the conceptus
  • Secretion of IFN is positively associated with
    conceptus size.
  • Administration of bST.

Maternal recognition of pregnancy
  • Mother quickly becomes cognizant of the
    cleavage-stage embryo within her body.
  • Mother reacts to embryo presence, but its not
    enough for the pregnancy to proceed.

Maternal recognition of pregnancy
  • For maternal recognition it is necessary
  • The normal cyclic regression of CL be prevented
    in order to maintain progesterone production.
  • The conceptus has also to ensure that an adequate
    supply of maternal blood reaches the sites of

Maternal recognition of pregnancy
  • The conceptus is recognized as foreign by the
    mother and it must nevertheless take steps to
    avoid a losing confrontation with the maternal
    immune system.
  • The conceptus does not become vascularized by the
    host's blood supply.

Maternal recognition of pregnancy
  • The ways in which different species
  • In human
  • Luteolysis is initiated by an intraovarian
    mechanism, although many believe it requires
    local production of PGF2a.

Maternal recognition of pregnancy
  • Luteolysis in these species is avoided by the
    intervention of chorionic gonadotrophin (CG)
  • The CG probably binds to LH receptors
  • The CG can stimulates progesterone production
  • The CG exerts a protective action against PGF2a

  • In rodents
  • Rodent do not produce a CG at all.
  • During pseudopregnancy in the rat, the cycle is
    lengthened to 12 days before the CL regress.
  • This extension of CL life span is the result of
    surges of pituitary prolactin release.
  • If the rat is pregnant, a series of placental
    lactogens and prolactin-like hormones produced by
    the placenta.

Maternal recognition of pregnancy
  • In pigs
  • Estrogen released by the trophoblast as it begins
    to elongate is probably the initial signal to the
    mother that she is pregnant.

Maternal recognition of pregnancy
  • In horses
  • The equine conceptus forms an encapsulated
    spherical structure between days 12 and 14.
  • The constant patrolling may be the key to the
    mechanism that inhibits PGF2a release.

Maternal recognition of pregnancy
  • In cattle and sheep
  • The conceptus begins to intervene in the
    luteolytic process three to four days before the
    CL actually become dysfunctional.
  • In these species, the antiluteolytic substance,
    an unusual Type I interferon (IFN)-t, has been
    reviewed on numerous occasions in the literature.
  • Its presence in the lumen clearly suppresses the
    normal pattern of pulsatile release of PGF2a.

Maternal recognition of pregnancy
Maternal recognition of pregnancy
  • Importance of progesterone
  • The concentrations of progesterone at a critical
    time before implantation is important for cows
  • Two logical possibilities for lower progesterone
    in the lactating dairy cows
  • Secretion by the corpus luteum is reduced
  • Metabolism of progesterone is increase

Maternal recognition of pregnancy
  • Importance of progesterone
  • Some factors may affect the metabolism and
    excretion of progesterone
  • Feed intake
  • Milk yield
  • Administration of exogenous progesterone

Embryonic loss
  • Much prenatal mortality occurs in all mammals.
  • Higher amount of embryonic wastage occurs
    following IVF and ET.
  • The majority of these losses occur prior to or
    during implantation.

Embryonic loss
  • Embryonic losses in sheep and cattle
  • It most occurring in the first 3 wk of pregnancy.
  • Natural asynchronies
  • The late onset of the first meiotic division may
    lead to some oocytes being delayed in their
  • A second natural cause of asynchrony may be due
    to delayed fertilization.
  • Finally, embryos are known to cleave at different

Embryonic loss
  • Injection interferons have ability to improve
    pregnancy success in ewes may be due
  • The rescue of embryos delayed.

Embryonic loss
  • Pig conceptuses attain control over maternal
    progesterone production
  • Releasing estrogen and probably other factors
    just prior to the time the CL would normally
  • The second consequence is that it induces the
    massive release of uterine secretions from the
    uterine glandular and surface epithelium

Pregnancy-Associated Glycoproteins (PAG)
  • In 1982 the partial purification and
    characterization of a pregnancy-specific protein
    (PSP-B) was reported from cattle.
  • More recently, isolated several isoforms of PAG
    from bovine placental tissue.

Pregnancy-Associated Glycoproteins (PAG)
  • It is now clear that PSP-B and PAG-1 are
    identical in sequence.
  • The presence of PAG-1 (or PSP-B) in blood serum
    has provided the basis of a potentially useful
    pregnancy test in cattle.

Pregnancy-Associated Glycoproteins (PAG)
  • The antigen generally becomes detectable by about
    day 20 postbreeding.
  • In cattle, concentrations of the antigen rise
    gradually during gestation and peak just prior to

Pregnancy-Associated Glycoproteins (PAG)
  • The PAG have a well-defined peptide- binding
  • They are relatively hydrophobic polypeptides.
  • They are unlikely to have enzymatic activity.

Pregnancy-Associated Glycoproteins (PAG)
  • Two possible functions for PAG are suggested
  • They could be hormones, which, by virtue of their
    binding clefts, are able to bind specific cell
    surface receptors on maternal target cells.
  • The second suggestion is that PAG sequestered or
    transported peptides

Some research papers associated to this lecture
1-Pancarci, et al. 2002. Use of estradiol
cypionate in a presynchronized timed artificial
insemination program for lactating dairy cattle.
J. Dairy Sci. 85122131. 2- Franco, et al.
2006. Effectiveness of administration of
gonadotropin-releasing hormone at Days 11, 14 or
15 after anticipated ovulation for increasing
fertility of lactating dairy cows and
non-lactating heifers. Theriogenology 66
945954. 3- De Rensis, et al. 2008. Inducing
ovulation with hCG improves the fertility of
dairy cows during the warm season. Theriogenology
69 10771082 4- Bartolome, et al. 2005.
Strategic use of gonadotrophin-releasing hormone
(GnRH) to increase pregnancy rate and reduce
pregnancy loss in lactating dairy cows subjected
to synchronization of ovulation and timed
insemination. Theriogenology 63 10261037.