2. (PhD in Animal Nutrition & Physiology)
By: A. Riasi
(PhD in Animal Nutrition & Physiology)
Isfahan University of Technology, Isfahan, Iran
Advanced
Reproductive Physiology
(part 4)

3. Spermatozoa in female tract
In natural mating semen are introduced in:
Vagina
Cervix
Within the female tract spermatozoa are lost by:
Neutrophils’ phagocytosis
Physical barrier including the cervix

4. Spermatozoa in female tract
Two stages for spermatozoa transportation:
Rapid
Effect of oxytocin secretion
Effect of prostaglandins
Sustained

5. Spermatozoa in female tract
Factors may affect spermatozoa transport in cervix:
Sperm motility
Physicochemical change in cervix secretions
Sulfomucin
Sialomucin

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

7. Spermatozoa in female tract
Higher levels of fertilization promoting peptide (FPP) prevent capacitation
FPP is found in the seminal fluid.
FPP comes into contact with the spermatozoa upon ejaculation.
FPP has a stimulatory effect on adenosine which increases adenylyl cyclase activity in the sperm.

8. Spermatozoa in female tract
Other chemical changes:
Removal of cholestrol and non-covalently bound epididymal/seminal glycoproteins is important.
Increased permeability of sperm to:
Ca2+, HCO3− and K+
The increase of intracellular cAMP levels.

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

10. 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.

11. Sperm penetration A series of events take place in AIJ:
Acrosomal reaction
The vesicles sloughed, leaving the inner acrosomal membrane and the equatorial segment intact

12. Sperm penetration
A spermatozoon has to penetrate four layers before it fertilizes the oocyte:

13. Sperm penetration

14. Sperm penetration Two different proteins in sperm membrane: ZBR ARPR
Reaction ZBR and ZP3 facilitate the sperm and zona pellucida contact.
ARPR
Reaction of ARPR and ZP3 start the acrosomal reaction

15. Sperm penetration

16. Sperm penetration

17. Sperm penetration
Three changes occur in the oocyte after penetration of vitelline membrane:

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

19. Cleavage

20. Cleavage
Blastomeres formation
Totipotency potential

21. Cleavage
Dissociation and reaggregation of morula-stage blastomeres. (A) There is clear evidence for molecular differences between cells (ie, specification) as early as the four- to eight-cell stage [61–71,157,158]; yet, cell fates remain plastic. (B, C) Following dissociation, it is likely that a combination of cell sorting (arrows) and respecification restores the original status of the embryo. (D) Once cell–cell contacts have been reformed, development proceeds from the blastocyst stage. (E) If only ‘‘inner’’ or ‘‘outer’’ (shown) cells are reaggregated, cell sorting (arrows) is still likely to occur. (F) Outer cells remain competent to produce both ICM cells and additional TE cells (curved arrows), as they do in normal development. (G) A combination of cell sorting, regeneration of ICM cells from outer cells, and (potentially) respecification of outer cells to an ICM lineage restores the original status of the embryo. (Adapted from Maureen L. Condic, Stem Cells and Development , 2014 )

22. Cleavage

23. Increase conception rate
Embryonic mortality in the initial seven days of gestation:
Fertilization failure
Genetic defects
Impaired embryonic development

24. 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.

25. 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 conceptus.

26. 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.

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

28. 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)

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

30. 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)

31. 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 Ovsynch

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

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

34. Increase conception rate
One possible hormone injection and TAI schedule for the Presynch/Ovsynch protocol based on the results of Moreira et al., 2000

35. 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.

36. Increase conception rate
Estradiol plus progesterone based protocol
Exogenous P4 (progestins and Melangestrol acetate) has consequences:
Suppresses LH release
Alters ovarian function
Suppresses estrus
Prevents ovulation

37. Increase conception rate
Several studies found that P4 treatment suppress the growing phase of the dominant follicle.
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.

38. 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 TAI in anestrous cows?
The treatment with equine chorionic gonadotropin (eCG) may be effective.

39. Increase conception rate
Antiluteolytic strategies after AI:
Pharmacological
Mechanical
Nutritional
Management

40. Increase conception rate
Strategies to increase progesterone after AI:
Daily injection of progesterone
Using of progesterone releasing intravaginal device (PRID) during the days 5-9 after AI.
Inducing the formation of accessory corpora lutea using GnRH, LH or hCG and for ovulation of the first wave dominant follicle.

41. Increase conception rate
Effect of estrogen
Estrogen secretion from a large follicle during the days after AI may affect embryo survival.
This hormone has a central role in PGF production and luteolysis.

42. Increase conception rate
Some strategies for reducing estrogen after AI:
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

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

44. Increase conception rate
Antiluteolytic strategies:
Antiinflamatory drugs
Fat feeding
Bovine somatotropin (bST)

45. 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).

46. Increase conception rate

47. Increase conception rate

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

49. 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, 2004)
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).

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

51. 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.

52. 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 placentation.

53. 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.

54. 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 PGF2α release.
Maternal recognition of pregnancy

55. 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 PGF2α.
Maternal recognition of pregnancy

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

57. 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

58. 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.

59. 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 maturation.
A second natural cause of asynchrony may be due to delayed fertilization.
Finally, embryos are known to cleave at different rates.

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

61. 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.

62. It is now clear that PSP-B and PAG-1 are identical in sequence.
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.

63. The antigen generally becomes detectable by about day 20 postbreeding.
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 parturition.

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

65. Two possible functions for PAG are suggested:
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

66. Some research papers associated to this lecture
1-Pancarci, et al Use of estradiol cypionate in a presynchronized timed artificial insemination program for lactating dairy cattle. J. Dairy Sci. 85:122–131.
2- Franco, et al 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: 945–954.
3- De Rensis, et al Inducing ovulation with hCG improves the fertility of dairy cows during the warm season. Theriogenology 69: 1077–1082
4- Bartolome, et al 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: 1026–1037.