The Nature and Role of Pregnancy‐Associated Antigens and the Endocrinology of Early Pregnancy in the Ewe

Findlay, J. K.; Cerini, Mildred; Sheers, Marion; Staples, Linton; Cumming, I. A.

doi:10.1002/9780470720479.ch11

Cited by 5 publications

(2 citation statements)

References 23 publications

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“…In comparison, pig blastocysts produce these estrogens as early as day 12, thereby inhibiting uterine prostaglandin production, which causes regression of the corpus luteum in the absence of embryos. On the other hand, in sheep, anti-luteolytic activity may be exerted via a glycoprotein (Findlay et al 1979).…”

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confidence: 99%

The morphological and functional ultrastructure of cells in pre-implantation embryos

Pivko¹,

Makarevich²,

Olexíková³

et al. 2023

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Cells of pre-implantation embryos are equipped with many morphological and functional systems through which they can synthesize specific proteins and effectively ensure the protection of early embryonic development. Here we present evidence for the existence of these systems in morphologically normal and abnormal bovine blastocyst stage embryos in vivo at the ultrastructural and actin cytoskeleton levels. The appearance of organelles in the trophectoderm and inner cell mass (ICM) cells, responsible for their synthetic activities and their role in the development of early bovine embryos are described. We point out the importance of endocytic processes and the participation of extracellular vesicles in the formation of intercellular contacts and homeostasis of the embryo microenvironment. Several changes in the ultrastructural morphology of embryos produced by different methods (ICSI, parthenogenetic AC/DC electrical activation, IVF with separated sperm) and freezing/thawed embryos are described. We also show alterations occurred in the organelles after viral contamination of embryos with BHV-1 and BVDV viruses, and in embryos from over-conditioned cows. Recorded changes in organelles and appearance of cellular autophagic structures (vesicles, multivesicular bodies and autophagolysosomes) may negatively affect embryo metabolism and lead to the emergence of pathological processes in trophectoderm and ICM cells of preimplantation embryos.

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mentioning

confidence: 99%

The morphological and functional ultrastructure of cells in pre-implantation embryos

Pivko¹,

Makarevich²,

Olexíková³

et al. 2023

gpb

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“…1) while an ovine alpha-fetoprotein preparation behaved similarly. Whether the other proteins associated with pregnancy in ruminants, trophoblastin (Martal et al, 1979), chorionic somatomammotrophin (Martal & Djiane, 1977) and those proteins obtained from bovine uterine flushings and endometrium (Roberts, 1977;Laster, 1977) or the embryo (Findlay, Cerini, Sheers, Staples & Cumming, 1979), have immunoregulatory potential still has to be determined. If so, it would be interesting to speculate that some common substance may be present in preparations of all these proteins which confers upon them this immunological character.…”

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confidence: 99%

The early pregnancy factor of sheep and cattle

Nancarrow¹,

Wallace²,

As³

2019

Proc

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The appearance and production of an early pregnancy factor (EPF) has been studied in sheep and cattle. This factor can be detected in serum and tissues of pregnant animals by its synergistic action with antilymphocyte serum in reducing the number of rosettes formed in a rosette inhibition test. The range of the rosette inhibition titre for serum from non-pregnant animals was 4-10. Values higher than these were considered to indicate the presence of EPF. In one ewe EPF was detected 29.5 h after the onset of oestrus at which time a zygote was recovered. The transfer of sheep zygotes into unmated non-pregnant ewes, and the infusion of extracts of mouse zygotes into the oviducts ipsilateral to the side of ovulation in ewes caused an increase in the titre of serum from the recipient animals. Infusion of extracts of unfertilized mouse ova did not change the titre. Removal of zygotes or embryos resulted in a reduction in the titre within 48 h to non-pregnant values. Extracts of tissues analysed for the presence of EPF gave high titres when taken from early pregnant ewes whereas tissues from non-pregnant animals gave low values. Removal of the ovary containing the corpus luteum from sheep 4-5 days after mating and in which pregnancy was maintained by exogenous progesterone resulted in a decrease in titre during the following 2-4 days. Removal of the contralateral ovary or the induction of luteolysis with a prostaglandin F-2a analogue did not result in a decrease. In cattle, pregnancy diagnosis by the rosette inhibition test 4 days after an artificial breeding programme gave good agreement with conventional pregnancy testing methods, e.g. palpation per rectum and plasma progesterone assays. From these experiments we suggest that a substance 'zygotin' is released by the fertilized egg and stimulates the production of EPF, most probably from the ovary containing the corpus luteum. Zygotin may act directly on the ovary or via an intermediary substance released by the oviduct. The role of EPF is unknown. It does not appear to be necessary for the maintenance of pregnancy because ovariectomized sheep with no demonstrable EPF remain pregnant when given exogenous progesterone. Routine pregnancy testing in sheep and cattle is not practicable with the present rosette inhibition test.

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Immunological Diagnosis of Early Pregnancy

Findlay¹

1980

Immunological Aspects of Reproduction and Fertility Control

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The Nature and Role of Pregnancy‐Associated Antigens and the Endocrinology of Early Pregnancy in the Ewe

Cited by 5 publications

References 23 publications

The morphological and functional ultrastructure of cells in pre-implantation embryos

The morphological and functional ultrastructure of cells in pre-implantation embryos

The early pregnancy factor of sheep and cattle

Immunological Diagnosis of Early Pregnancy

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