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Biomedical subjects

K J Betteridge

Publications and source records attributed to K J Betteridge.

At least 73 records · Page 4Linked to original sources
PubMed1987

PGF-2 alpha release, progesterone secretion and conceptus growth associated with successful and unsuccessful transcervical embryo transfer and reinsertion in the mare.

The outcome of 23 collections and reinsertions of conceptuses on Days 10.5-13.5, 4 transfers of Day-10.5, and 13 transfers of Day-6.5 embryos (ovulation = Day 0) was monitored in 30 mares. Blood samples were taken before and after each procedure to measure plasma 15-keto-13,14-dihydroprostaglandin F-2 alpha (PGFM), and then daily for progesterone determinations. Mares were also subjected to daily teasing for detection of oestrus, and to uterine ultrasonography for tracing the development of the conceptus. After the reinsertions, 12/23 conceptuses were detectable immediately after the procedure. Of these, 1 developed into a normal foal but 11 disappeared during the next 4 days. All 4 Day-10.5 conceptuses transferred disappeared within 7 days. Of the 13 Day-6.5 conceptuses transferred, 8 were detectable by Day 11.5 and 5 of these developed into healthy foals. The 3 losses occurred between Days 14 and 25. Small increases in PGFM concentrations occurred in 8/23 collection-reinsertion procedures on Days 10.5-13.5 and after 2/25 Day-6.5 recoveries, but during none of the 13 Day-6.5 transfers. A marked reduction (greater than or equal to 40%) in progesterone concentration was noted within 24 h of the procedures in only one Day-10.5 embryo transfer and, in subsequent days, the disappearance of the conceptuses was associated with complete luteolysis in only 1 Day-6.5 transfer, 1 Day-10.5 transfer and 1 Day-12.5 reinsertion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Endocytotic activity in the endometrium during conceptus attachment in the cow.

The uptake of horseradish peroxidase tracer injected into the uterine lumen of the cow was studied during the period of conceptus attachment (Days 18-21; Day 0 = oestrus) and also in cyclic animals. Endocytosis occurred in pregnant and non-pregnant cows but was especially marked when circulating progesterone concentrations were high. By 20 min after injection, the tracer was located in apical endocytotic vesicles and in organelles of the lysosomal system. In addition, some of the horseradish peroxidase-containing vesicles were associated with the lateral membranes of the cells and the tracer was also present in the intercellular spaces and beneath the basal membrane, especially in pregnant animals by the time of conceptus attachment. There was no evidence that pinopod-like functions could be attributed to large cytoplasmic protrusions from endometrial cells. Rather, the protrusions seemed to be involved in secretory processes. The presence of clear vesicles among the endocytotic vesicles suggested a coupled secretory-endocytotic activity of the cells, the significance of which remains to be determined.

Animals↗
PubMed1985

Production of sexed calves from frozen-thawed embryos.

Three experiments have been conducted with the aim of producing calves from frozen, sexed embryos by combining embryo splitting and cytogenetic methods. In the first experiment, the efficacy of the bisection technique was assessed by transcervical transfer of 10 monozygotic pairs of half embryos to 10 synchronised heifers. Thirteen calves were produced, including four sets of identical twins. In the second experiment, one of the halves of each of eight split embryos was transferred while the other was processed for sexing by identification of the sex chromosomes. In the third experiment, one of the halves from each of 28 embryos was frozen while the other half was used for sexing. Eleven of the 16 which were sexed have been transferred with the production of three calves of the predicted sex. The overall sexing rate was 60 per cent and the calving rate following transfer of sexed embryos was 60 per cent and 23 per cent for fresh and frozen halves respectively.

Animal Husbandry↗
PubMed1984

In vitro fertilization and cleavage of in vivo matured bovine oocytes.

The effect of the interval between onset of estrus and oocyte collection on in vitro fertilization (IVF) rates has been investigated. The oocytes were surgically collected 6-18 h (Group I), 19-24 h (Group II), 25-29 h (Group III) and 30-36 h (Group IV) after the beginning of estrus. Recognizable stages of nuclear maturation were identified in 54.9% of the oocytes used for IVF (5.9% at germinal vesicle, 31.4% at metaphase I, 17.6% at metaphase II); the other 45.1% were degenerate. Considerable between- and within-cow variation in oocyte morphology, oocyte maturation and IVF results was observed. The overall fertilization and cleavage rates (to four-cell stages) were 26.5 and 6.0%, respectively. The fertilization rate increased as the interval between onset of estrus and collection increased and was optimal 30-36 h after onset. Thus, onset of estrus proved an effective means of timing oocyte collection for IVF.

Journal Article↗
PubMed1982

Transfer of embryos from bovine leukaemia virus-infected cattle to uninfected recipients: preliminary results.

One hundred and fifty-one, day 6 or 7, embryos collected from cattle infected with bovine leukaemia virus (BLV) were transferred to uninfected recipients. Thirty-two pregnancies resulted. Two animals aborted at seven months. Three sets of twins and one single calf were still-born. The remaining 26 pregnancies produced 27 live calves which were raised to six months of age. All of the recipients, pregnant and non-pregnant, and all of the calves remained serologically negative for antibodies to BLV-glycoprotein antigen.

Animals↗
PubMed1982

Transmission electron microscopy of horse embryos 3-16 days after ovulation.

The 23 embryos were obtained by flushing the reproductive tract. Though the general cytology was observed, most attention was given to the formation of the embryonic capsule. It first appeared as a thin uniform layer on the inner surface of the zona pellucida of embryos recovered from the uterus on Day 6. By Day 8 the capsule was about 1 micron thick and the zona pellucida had been shed. In fixed embryos of 11 days and over the capsule was 3 microns thick and had a finely stippled but otherwise homogeneous appearance.

Animals↗
PubMed1982

Development of horse embryos up to twenty two days after ovulation: observations on fresh specimens.

Forty nine embryos, twenty unfertilized eggs and five other fresh eggs of 'doubtful' status have been recovered from 58 pony mares in 122 flushes up to 22 days after ovulation. The fresh egg or embryo recovery rate was 78% with surgical methods (or at slaughter) and 40-60% with non-surgical methods of recovery. The fertilization rate was about 70%. It has been confirmed that horse embryos normally enter the uterus as blastocysts 5-6 days after ovulation. Three features of early embryo morphology have become clearer upon comparison with unfertilized eggs of similar ages; early embryos are often ellipsoidal in shape; dispersal of most of a thick gel coat seems to be hastened by fertilization; gradual disappearance of refractile granules from the perivitelline space is similar in fertilized and unfertilized eggs. A tense, transparent, acellular capsule (considered to be different from the zona pellucida) is acquired by the spherical blastocysts within the uterus and persists at least until a diameter of 34 mm is attained (at 21 days in the present series). The capsule seems to be analogous, in part, with the 'neozona' described in rabbit blastocyst before attachment, and trophoblastic cells appear to be involved in its formation. Cleavage stages of oviductal embryos and diameters of uterine blastocysts from this series have been described and illustrated and used to extend previous knowledge of early growth patterns in horse embryos.

Animals↗
PubMed1980

Chromosomal analysis of 159 bovine embryos collected 12 to 18 days after estrus.

One hundred and fifty-nine embryos were analysed in conjunction with embryo transfer studies. Chromosome preparations were made from small biopsy fragments of trophoblast, from large portions of trophoblast and the inner cell mass, or from the entire embryo. Results obtained from fragments were similar to those obtained from large portions of trophoblast and inner cell mass. No structural chromosomal abnormalities were observed. Single triploid, diploid-triploid and diploid-hexaploid and 66 diploid-tetraploid embryos were found. The 41.5% incidence of diploid-tetraploid embryos was relatively high, and appeared to be associated with a donor factor. The transfer of 49 biopsied and analysed embryos to recipients resulted in 15 pregnancies, seven with diploid-tetraploid embryos having up to 25% of polyploid cells. The diploid-triploid and diploid-hexaploid embryos were among the transfers that did not result in pregnancy. The low incidence of embryos with chromosomal abnormalities, excluding the diploid-tetraploid embryos, may have been due to the embryos being analysed at 12 to 18 days of age rather than at an earlier age before death or degeneration could have occurred.

Animals↗
PubMed1980

Collection, description and transfer of embryos from cattle 10--16 days after oestrus.

Of 226 donor cattle treated with PMSG to induce superovulation, 76.5% responded with 3 or more ovulations. Flushing at surgery or slaughter 10-16 days after oestrus recovered eggs and embryos that represented 49.3% of the number of ovulations. Of those recovered, 73.3% were embryos, an average yield of 4.0 embryos/treated cow or 4.8 embryo/flushed cow. The location of eggs and embryos was determined in 65 of the donors. Embryos and unfertilized eggs (6.1% of those recovered) were occasionally found in the oviducts. Empty zonae pellucidae were also found in the uterus on all days. The lengths, or diameters, of embryos were extremely variable within days and within donors, but mean values indicated logarithmic growth between Days 10 and 16. Eighty-four synchronous (+/- 1 day) recipients received single embryos, and 51 recipients twin embryos, by surgical transfer. Pregnancies were obtained in recipients up to Day 16 but not on Day 17, indicating the stage by which an embryo must be present to prevent luteolysis. The overall pregnancy rate at Day 42 was 50.4% and further 18.1% of the recipients exhibited extended oestrous cycles. Of 35 recipients that were allowed to go to term, 12 lost their pregnancies, most often between Days 42 and 63.

Abortion, Veterinary↗
PubMed1979

The location of eggs retained in the oviducts of mares.

The oviducts of 24 mares were examined to determine the site of retention of unfertilized eggs. The ampullary-isthmic junction regions of 42 of the 48 oviducts were serially sectioned and examined histologically. The remaining parts of the oviducts were flushed and the flushings searched microscopically. Of 45 eggs located, 40 were in the sectioned segments of 24 oviducts and only 5 were in the flushings. All but one of the sectioned segments contained prominent masses of material obstructing the lumen, but these were apparently not the direct cause of egg retention since eggs were found on both sides of them.

Animals↗
PubMed1979

Embryo transport through the mare's oviduct depends upon cleavage and is independent of the ipsilateral corpus luteum.

Two experiments were conducted using 14 mares. In Exp. 1, mares were inseminated with semen treated with TEPA, which, in other species, has been shown to lead to an arrest in ovum cleavage at 2--4 cells. The oviducts and/or uterus were then flushed 7--10 days after ovulation in 6 mares (Group A) or 2--6 days after ovulation in 5 mares (Group B). Fresh eggs were found in the oviduct flushes of 5 Group A and 5 Group B mares: 9 of the 10 eggs appeared to have cleaved, but none had developed beyond 16-cells. Seven eggs contained spermatozoa and 3 of 4 eggs from each group showed evidence of fertilization when examined ultrastructurally. Group A mares had thus retained fertilized eggs in the oviduct beyond the time at which they would normally have entered the uterus (6 days), indicating that development beyond at least the 2- to 4-cell stage is necessary for normal transport. In Exp. 2, 5 attempts were made to recover the embryo within 4 days of ovulation and transfer it to the contralateral oviduct. A single pregnancy resulted, indicating that a unilateral interaction with the corpus luteum was not necessary for the transport of the embryo to the uterus.

Animals↗
PubMed1979

Oestrogens and androgens in blastocoelic fluid and cultures of cells from equine conceptuses of 10-22 days gestation.

Six samples of blastocoele fluid recovered between 10 and 22 days gestation were tested in human clinical radioimmunoassay systems measuring total oestrogens and total androgens. The results were erratic but in 5 cases measurements for oestrogen equivalent to between 1000 and 70,000 pg/ml and for androgen between 1000 and 85,000 pg/ml were recorded. Cells from two blastocysts were cultured in medium 199 with and without horse serum. When the used media were assayed, values equivalent to at least 8000 pg oestrogen/ml were obtained on 7 of 11 occasions. In 9 of 11 samples the androgen concentration exceeded 700 pg/ml. In control media the oestrogen and androgen concentrations did not exceed 120 and 360 pg/ml respectively.

Androgens↗
PubMed1975

A surgical technique applied to the study of tubal eggs in the mare.

An efficient surgical technique of collecting eggs from the oviducts of mares is described. Within 6 days after ovulation recovery was successful in 22/29 mares. The technique has been used to investigate the retention and ageing of eggs in the oviducts and to determine the origin and the nature of the accessory CL during pregnancy.

Age Factors↗