Search PubMed⌕ Search

Biomedical subjects

G Evans

Publications and source records attributed to G Evans.

At least 37 records · Page 2Linked to original sources
PubMed2004

Prevention and genetic testing for breast cancer: variations in medical decisions.

The discovery linking the genes BRCA1&2 to familial breast cancer played an important role in the clinical practice of geneticists and physicians. The availability of genetic tests for BRCA gene mutations prompted cancer geneticists to give information about genetic risk and to assess many women with a personal or family history of breast or ovarian cancer to inform them of preventive measures. These consist mainly of breast self-examination, mammography screening, chemoprevention and prophylactic surgery (mastectomy, oophorectomy). This paper examines clinical practices related to hereditary breast cancer testing and introduces a number of results from a survey carried out, between 1996 and 1998, in three clinics located in Montreal (Quebec, Canada), Marseilles (France) and Manchester (Great Britain). Results show substantial differences in the way cancer geneticists deal with environmental risk factors, breast and ovarian cancer testing, and chemoprevention and prophylactic surgery. Differences across cities persist in the multivariate analysis, suggesting that attitudes towards preventive measures may be partially explained by cultural factors. Different dimensions of culture are discussed including the social representation of health and risk, the interpretation of scientific evidence and the role of innovation leadership.

Adolescent↗
PubMed2004

Preservation and artificial insemination of sexed semen in sheep.

Sperm-sexing technology using flow cytometry is in advanced stages of development for the sperm of several species. The sorting process could compromise sperm viability and sperm require specific handling procedures both before and after sorting to maintain the integrity and function of the sorted sperm. Standard freezing protocols have been modified for post-sorting cryopreservation of sperm and frozen sperm have been successfully thawed, sorted, refrozen and subsequently used to produce offspring. The relatively low numbers of available sorted sperm have, in some cases, led to modification of artificial insemination techniques to maximise efficiency of use. Multiple ovulation and embryo transfer, or in vitro fertilisation and associated technology, may lead to the more efficient use of sexed sperm.

Animals↗
PubMed2004

Characterization and localization of membrane vesicles in ejaculate fractions from the ram, boar and stallion.

Membrane vesicles, separated by differential centrifugation from the seminal plasma, were detected in the sperm-rich ejaculate fractions of four boars and three stallions, and in the whole ejaculates of seven rams. The volume and percentage of vesicles, determined by a stereological technique, were higher in the sperm-rich than in the post-sperm-rich fractions of the boar and stallion ejaculates, and no vesicles were detected in the pre sperm-rich fractions. Vesicles were examined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). For boar, stallion and ram semen, the mean (+/- s.e.m.) vesicle diameters were 130.9 +/- 3.22 (range 18-577), 164.1 +/- 4.42 (range 15-671) and 159.7 +/- 2.92 nm (range 22-986), respectively, although they were not significantly different (p = 0.709). The vesicles had approximately round (TEM) or spherical shape (SEM), were surrounded by single, double or multi-laminar membranes, and were trapped within ample amorphous material, sometimes containing short, flattened membranous elements. The majority of the vesicles had a clear interior but some contained granule-dense material. Ram membrane vesicles, purified from ultracentrifuged plasma by size exclusion chromatography, kept their round shape and the amorphous material was less evident compared with the sections taken before purification. This is the first report to identify seminal plasma membrane vesicles in the different fractions of ejaculated semen in the boar and stallion, and confirms their presence in ram seminal plasma. The origin and function of these vesicles are yet to be elucidated.

Animals↗
PubMed2004

Production of lambs after the transfer of fresh and cryopreserved in vitro produced embryos from prepubertal lamb oocytes and unsorted and sex-sorted frozen-thawed spermatozoa.

Cumulus-oocyte complexes from hormone-stimulated 3-4-week-old (n=43) and 6-7-week-old (n=12) prepubertal lambs were matured in vitro and incubated with unsorted, or X- or Y-spermatozoa separated with a high-speed cell sorter (SX MoFlo)frozen-thawed. Presumptive zygotes were then cultured to the blastocyst stage, and transferred to recipients fresh or after cryopreservation (frozen). Oocyte cleavage was higher (p <0.05) with unsorted (515/926, 55.6%) than X- or Y-spermatozoa (261/672, 38.8% and 229/651, 35.2%, respectively) and blastocyst formation (% zygotes) by Day 9 of in vitro culture was lower (p <0.05) for X- (102/261, 39.1%) than unsorted spermatozoa (249/515, 48.3%), but did not differ between Y-spermatozoa (103/229, 45.0%) and unsorted spermatozoa, or between X- and Y-spermatozoa (p >0.05). For fresh embryos, survival to term was 50.0% (3/6) for unsorted, 0.0% (0/6) for X- and 16.7% (1/6) for Y-spermatozoa-derived embryos (p >0.05), and for frozen embryos was 4.0% (2/50) for unsorted, 9.1% (2/22) for X- and 2.9% (1/34) Y-spermatozoa-derived embryos (p >0.05). Of the two lambs born from X-spermatozoa-derived embryos, one was female (50%), and from the two Y-spermatozoa-derived lambs, both were male (100%), demonstrating that lambs can be produced after the transfer of fresh and cryopreserved IVP embryos derived from prepubertal lamb oocytes and frozen-thawed sex-sorted sperm.

Animals↗
PubMed2004

Latent antithrombin and its detection, formation and turnover in the circulation.

It is now apparent that the inactivated latent and cleaved conformers of antithrombin (AT) are of pathological significance. Using a single-run electrophoretic technique that allows the quantitative assessment of these conformers in 2 microL plasma, we show that near 3% of the total AT in the circulations of normal individuals is in latent conformation. Only trace amounts of cleaved AT were observed. The slow decline in AT activity on incubation of plasma at 37 degrees C was shown to be almost wholly due to a transition of native AT to its inactive latent form. Also initial studies in the rabbit indicate that the latent form, like the cleaved, has an identical circulatory half-life to that of native AT. We deduce that the steady concentration of latent AT in the circulation is due to the transition of some 10(12) molecules of AT per second balanced by an equivalent clearance of the latent form. Examples of clinical applications of the new technique include its use as a comprehensive single-step screen for genetic variants associated with AT deficiency, and notably the potential it provides to monitor the changes responsible for the loss of AT in the shock syndromes.

Animals↗
PubMed2004

Components of a platelet-activating factor-signaling loop are assembled in the ovine endometrium late in the estrous cycle.

Pulsatile release of uterine prostaglandin F(2alpha) (PGF(2alpha)) induces luteolysis in ruminants. Exogenous PAF is well known to cause PGF(2alpha) release from the ovine uterus. This study examines whether the components of a PAF-signaling loop exist in sheep at the time luteolysis is normally initiated. Day 14 of the cycle was the first day the uterus responded to an infusion of PAF, inducing a significant short-term increase in circulating levels of the PGF(2alpha) metabolite. There was a significant increase of PAF concentration (P < 0.001) in the endometrium and PAF release by tissue explants (P < 0.001) from day 10 to day 16 of the cycle. Endometrial tissue PAF receptor mRNA expression was induced (P < 0.01) by estradiol and progesterone treatment of animals, and transcripts were present between days 10 and 16 of the estrous cycle. Western analysis of endometrial tissue showed marked upregulation of PAF receptor protein expression from day 14 of the cycle, and immunolocalization studies showed that the receptor expression was predominantly around the endometrial glands. PAF:acetylhydrolase was primarily located within the lumen of the endometrial glands. The study shows that a PAF-signaling loop was assembled within the ovine endometrium at the time that PGF(2alpha) pulsatility was first observed.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed2004

Birth of lambs of a pre-determined sex after in vitro production of embryos using frozen-thawed sex-sorted and re-frozen-thawed ram spermatozoa.

UNLABELLED: The characteristics and functional capacity of ram spermatozoa frozen-thawed prior to and after flow cytometric sorting was assessed after incubation (37 degrees C; 6 h), in vitro fertilisation (IVF), and transfer of fresh and vitrified in vitro produced embryos. Frozen-thawed spermatozoa from two rams were allocated to four treatment groups: (i) non-sorted (CONTROL); (ii) sorted (FS); (iii) sorted then re-frozen (FSF) and (iv) re-frozen control (FCF). Frozen-thawed samples were separated into X- and Y-chromosome bearing spermatozoa using a high-speed sperm sorter after density gradient centrifugation (X: 88 +/- 1.5% and Y: 87 +/- 1.1% purity). After 6 h incubation (37 degrees C), the percentage of motile spermatozoa was higher (P < 0.001) for FS (84 +/- 2.0%) compared with all other treatments ( CONTROL: 36 +/- 3.3%, FSF: 28 +/- 3.1%, FCF: 20 +/- 2.0%). In a sperm migration test greater numbers of FS spermatozoa penetrated 5 mm into the artificial cervical mucus compared with spermatozoa from all other treatments (152 +/- 39.4 vs 31 +/- 9.2 spermatozoa respectively; P < 0.05). Fertilisation and cleavage rates were higher (P < 0.05) for in vitro matured oocytes inseminated with CONTROL compared with FSF spermatozoa. However, the Day 7 blastocyst development rate was higher for oocytes inseminated with FSF (62.2%) than FS and CONTROL spermatozoa (52.7 and 50.0%; P < 0.05). The number of ewes pregnant (Day 60), lambing and the in vivo embryo survival rate was greater (P < 0.01) after the transfer of fresh embryos rather than vitrified embryos derived from X- and Y-spermatozoa (67.6, 64.7 and 41.2% vs 29.6, 25.9 and 14.8% respectively). Twenty-six of the 30 (86.7%) lambs derived from sex-sorted spermatozoa were of the correct sex. These results demonstrate that frozen-thawed ram spermatozoa can be sex-sorted for immediate or future use after re-cryopreservation and, in conjunction with IVF and embryo transfer, can be used to efficiently produce offspring of pre-determined sex.

Animals↗
PubMed2003

Dento-osseous changes as diagnostic markers in familial adenomatous polyposis families.

BACKGROUND: We have previously described a weighted index for determining the diagnostic significance of dento-osseous changes observed on dental panoramic radiographs (DPRs) in individuals at 50% risk of inheriting Familial Adenomatous Polyposis (FAP). A diagnostic test based on this index (Dental Panoramic Radiograph Score, DPRS) was shown to have a sensitivity of 69% and specificity of 100%. OBJECTIVES: To evaluate the validity of the diagnostic test in an independent sample of individuals at 50% risk of inheriting FAP. DESIGN: A retrospective assessment of DPRs in individuals at 50% risk of inheriting FAP. SUBJECTS AND METHODS: A final year dental student assessed blindly and independently, DPRs from an independent sample (n = 119) of affected (n = 26), unaffected (n = 78) and clinically low risk individuals (n = 15). This revealed a sensitivity and specificity of 62 and 97% respectively which is in close agreement with results of the previous study. The dental student's training in assessing DPRs was previously tested using radiographs from 81 individuals from our original study. Weighted Kappa statistics were used to test for agreement. A kappa score of 0.82 (95% confidence interval 0.70-0.93) indicated almost perfect agreement. MAIN OUTCOME: The DPRS is a reproducible and valid index for assessing the diagnostic significance of dentoosseous changes, in individuals at 50% risk of FAP, even in relatively inexperienced hands.

Adenomatous Polyposis Coli↗
PubMed2003

In vitro and in vivo assessment of functional capacity of flow cytometrically sorted ram spermatozoa after freezing and thawing.

The effect of sex sorting and freeze-thawing on the viability and fertility of ram spermatozoa was investigated in the present study. Non-sorted (control) frozen-thawed spermatozoa had a higher motility and forwards progressive motility (FPM) than sorted frozen-thawed spermatozoa (60.9 +/- 2.9% v. 57.0 +/- 3.3% and 4.0 +/- 0.1 v. 3.5 +/- 0.1 FPM, respectively; P < 0.001) after incubation (6 h at 37 degrees C). Sorted and non-sorted (control) frozen-thawed spermatozoa had similar acrosome integrity (73.7 +/- 1.8% v. 75.2 +/- 2.1%, respectively) after thawing and incubation. A greater proportion of sorted spermatozoa displayed chlortetracycline staining patterns that were characteristic of capacitation (22.0 +/- 2.8%; P < 0.05) than non-sorted (control) spermatozoa (15.4 +/- 2.6% B pattern) before freezing. Overall, more sorted frozen-thawed spermatozoa showed patterns characteristic of being acrosome reacted (12.8 +/- 0.7%; P < 0.01) and less were uncapacitated (35.5 +/- 0.6%; P < 0.05) than non-sorted (control) frozen-thawed spermatozoa (7.7 +/- 0.8%; and 38.6 +/- 0.6% for AR and F pattern, respectively). Similar numbers of non-sorted (control) and sorted frozen-thawed spermatozoa migrated through artificial cervical mucus after 1 h (76.4 +/- 11.9 v. 73.9 +/- 11.9 spermatozoa, respectively). The distance travelled by the vanguard spermatozoon was also similar (56.9 +/- 7.8 v. 38.6 +/- 5.8 mm for control and sorted spermatozoa, respectively). Sorted and control frozen-thawed spermatozoa displayed a similar pattern of binding to, and release from, an oviduct epithelial cell monolayer (OECM), but sorted frozen-thawed spermatozoa were released more rapidly (P < 0.05) than non-sorted (control) frozen-thawed spermatozoa. The pregnancy rate was higher for ewes inseminated with 100 x 10(6) (commercial control) frozen-thawed spermatozoa (59%) than for 5, 10, 20 and 40 x 10(6) total sorted frozen-thawed spermatozoa (41% overall; P < 0.001). Insemination of 16 x 10(6) resulted in a higher pregnancy rate (31%) than 10(6) (17%; P < 0.05), but was similar to ewes that received 4 x 10(6) sorted frozen-thawed spermatozoa (24%). Time of insemination (54, 58 and 62 h after sponge removal) had no effect on pregnancy rate. Pregnancy in gonadotrophin-releasing hormone-treated ewes was affected by insemination dose (P < 0.05) but not sperm type (sorted and non-sorted) or ram. Pregnancy was higher after insemination of 40 x 10(6) than 5 or 20 x 10(6) non-sorted (control) or sorted frozen-thawed spermatozoa (70%, 33% and 35%, respectively; P < 0.05). Sorted frozen-thawed spermatozoa may have a shorter viability within the female tract than non-sorted frozen-thawed spermatozoa.

Acrosome↗
PubMed2003

Flow cytometric sorting of frozen-thawed spermatozoa in sheep and non-human primates.

Research was conducted in sheep to determine an effective preparation method for high-purity sorting of frozen-thawed spermatozoa. The efficacy of sorting frozen-thawed spermatozoa was then investigated in several non-human primate species. An aliquot of each ejaculate (three rams, three ejaculates per ram) was processed as a fresh control (FRESH). Frozen spermatozoa were thawed and prepared for sorting by no further processing (FT-NEAT), washing (FT-WASH) or gradient centrifugation (FT-GRADIENT) and evaluated for motility at 1 h post-staining and motility and acrosomal status at 0 and 4 h post-sorting. Samples were analysed using a high-speed cell sorter. High levels of purity for X- and Y-enriched samples were achieved for all treatments (85-92%). The percentage of motile spermatozoa before sorting was lower (P < 0.05) for frozen-thawed samples (FT-NEAT: 32.7 +/- 2.5%; FT-WASH: 32.2 +/- 3.3%; FT-GRADIENT: 73.9 +/- 3.7%) compared with FRESH (83.3 +/- 1.2%). Post-sorting, the percentage of motile spermatozoa before and after incubation for FT-NEAT (60.0 +/- 5.1% and 27.2 +/- 6.1% for 0 and 4 h, respectively) was lower than that for FRESH (87.8 +/- 0.9% and 83.3 +/- 1.2% for 0 and 4 h, respectively; P < 0.05), FT-WASH (80.0 +/- 2.4% and 71.7 +/- 3.6% for 0 and 4 h, respectively; P < 0.05) and FT-GRADIENT (84.4 +/- 1.3% and 77.2 +/- 1.7% for 0 and 4 h, respectively; P < 0.05). Vanguard sperm migration distance through artificial cervical mucus was lower (P < 0.05) for FT-NEAT (17.7 +/- 1.7 mm) compared with FT-WASH (29.1 +/- 3.8 mm) and FT-GRADIENT (28.4 +/- 2.0 mm) and similar (P < 0.05) to FRESH (23.7 +/- 1.8 mm). Sample preparation using a modified wash method enabled high-purity sorting (range 86-97% purity) of frozen-thawed epididymal spermatozoa in the baboon (Papio hamadryas), common marmoset (Callithrix jacchus) and common chimpanzee (Pan troglodytes). For all non-human primate species, sorted spermatozoa were progressively motile (marmoset: 20.5 +/- 5.5%; baboon: 37.5 +/- 2.5%; chimpanzee: 73.0 +/- 2.0%), acrosome intact (marmoset: 68.5 +/- 7.5%; baboon: 89.5 +/- 1.5%; chimpanzee: 84.0 +/- 1.0%) and able to penetrate an artificial cervical mucus. In summary, high-purity sorting of frozen-thawed ram and non-human primate spermatozoa with recovery of progressively motile, acrosome-intact spermatozoa was possible after processing to remove cryodiluent.

Animals↗
PubMed2003

A glycine to aspartic acid substitution of COL2A1 in a family with the Strudwick variant of spondyloepimetaphyseal dysplasia.

BACKGROUND: Spondyloepimetaphyseal dysplasia (SEMD) is one of a clinically heterogeneous group of skeletal disorders, characterized by defective growth and modelling of the spine and long bones. Common clinical features include disproportionate short stature, malformed vertebrae and abnormal epiphyses or metaphyses. Some cases have been associated with mutations in the COL2A1 gene. AIM: To determine whether the autosomal dominant Strudwick-type SEMD in a three-generation family, showing specific phenotypical features such as chest deformity, limb shortening, myopia and early-onset degenerative osteoarthrosis, might be caused by a novel COL2A1 mutation. DESIGN: Genetic testing and clinical examination of family members. METHODS: Direct sequencing of PCR-amplified genomic DNA from the COL2A1 gene. RESULTS: A point mutation within exon 20 of the COL2A1 gene was identified that substituted a glycine for an aspartic acid residue at codon 262. DISCUSSION: All previously reported autosomal dominant mutations causing SEMD have substituted an obligate glycine within the triple helix, in particular at codons 292, 304 and 709 in the three reported Strudwick-type patients. Additionally, a recurrent glycine substitution at codon 154 has been identified in two unrelated Finnish cases with radiological features consistent with the Strudwick subtype. Our sixth helical glycine substitution extends the mutational spectrum and genotype/phenotype correlations of Strudwick-type SEMD.

Aspartic Acid↗
PubMed2003

Modification of standard freezing media to limit capacitation and maximise motility of frozen-thawed equine spermatozoa.

OBJECTIVE: To investigate cryopreservation-induced capacitation-like changes in equine spermatozoa frozen in three different media using chlortetracycline (CTC) fluorescence staining analysis. PROCEDURE: Semen collected from three stallions was diluted in one of three centrifugation media and, after centrifugation and removal of supernatant, extended in corresponding freezing media containing additional egg yolk, glycerol, lactose and Equex paste. The semen was frozen in 5 mL straws and the spermatozoa assessed for motility and membrane quality after thawing. RESULTS: Following centrifugation, spermatozoa diluted with modified Kenney's Centrifugation Medium (MKCM) displayed a higher percentage of (normal) F pattern (94.3%) compared with spermatozoa in Kenney's Centrifugation Medium (KCM) (84.9%) and Glucose-EDTA Centrifugation Medium (GECM) (85.2%). Conversely, the percentage of spermatozoa displaying the (capacitated) B pattern was higher in the KCM (14.1%) and GECM (13.8%) than in the MKCM (5.0%). Following freezing-thawing, there were lower percentages of spermatozoa displaying the AR (acrosome reacted) pattern in modified Kenney's Freezing Medium (MKFM) (45.6%) compared with Kenney's Freezing Medium (KFM) (61.4%) and lactose-EDTA Freezing Medium (LEFM) (61.1%). There was a correspondingly higher percentage of spermatozoa displaying the B pattern in MKFM (52.3%) compared with KFM (37.9%) and LEFM (38.6%). There was no significant difference between the freezing media in the percentage of spermatozoa displaying the F pattern. The percentage of progressively motile spermatozoa was also influenced by the type of freezing medium (P < 0.001). Post-thaw percentages of progressively motile spermatozoa, frozen in MKFM, KFM, and LEFM, were 31.4, 25.8 and 23.3%, respectively. CONCLUSION: MKFM was the preferred medium for cryopreservation of equine spermatozoa due to its superior protection against changes in motility and membrane quality compared with the other freezing media studied.

Animals↗
PubMed2002

The spectrum of pathology in central core disease.

Central core disease is a congenital myopathy with muscle weakness defined pathologically by the presence of extensive areas in muscle fibres that are devoid of oxidative enzyme activity. The gene responsible has been shown to be the ryanodine receptor 1 on chromosome 19q13 and mutations have now been identified in several patients. Some cases with the morphological defect remain molecularly undefined, particularly those studied before molecular studies were available. We have studied three families with congenital onset, each with a dominantly inherited mutation in a C-terminal exon of the ryanodine receptor 1. They illustrate the spectrum of pathology that can be observed in patients with the myopathic features of central core disease. We show that extensive fibrosis and fat may be present, type 1 fibre uniformity may occur in the absence of cores; cores may be central or peripheral, single or multiple; and that an appearance of multiple focal minicores might cause a diagnostic pathological dilemma. In addition, we show the value of immunocytochemistry in identifying cores, in particular the use of antibodies to desmin and gamma-filamin.

Adult↗
PubMed2002

MonoFIX-VF, a new mono-component factor IX concentrate: a single-centre continuous-infusion study.

MonoFIX-VF, a monocomponent factor IX concentrate, has replaced the use of Prothrombinex-HT as the treatment of choice for patients with factor IX deficiency in Australia. The haemostatic effect of MonoFIX-VF, administered by continuous infusion, was assessed in four subjects being treated for 10 bleeding episodes including five surgical procedures. MonoFIX-VF was found to be a safe and effective treatment for patients with haemophilia B.

Drug Evaluation↗
PubMed2002

Retrojugular approach for carotid endarterectomy: a prospective cohort study.

The purpose of this study was the examination of the feasibility of the retrojugular approach for carotid endarterectomy and the investigation of its safety and effectiveness. A consecutive prospective cohort of 43 patients who underwent carotid endarterectomy with the retrojugular approach was compared with a retrospective cohort of 43 patients who underwent surgery with the standard antejugular technique. Age, sex, comorbidity, diagnostic investigations, and indications for surgery were comparable in both groups. In the retrojugular group, a carotid shunt was used in 18 patients (42%) and a patch closure in 15 patients (35%), and in the antejugular group, a carotid shunt was used in 43 patients (100%) and a patch closure in 20 patients (47%). There were no perioperative deaths, strokes, nerve injuries, or 30-day postoperative neurologic events. Wound hematomas were equally distributed in both groups (5%). Transient hoarseness was present in two patients in the antejugular group. The mean operative time was 72 +/- 15 minutes for the retrojugular technique and 100 +/- 27 for the antejugular technique (P <.0001). The hospital stay was 2 +/- 1 days in both groups. In conclusion, the retrojugular approach appears to be safe and the operative time may be shorter than with the antejugular approach.

Aged↗
PubMed2002

Capacitation-like changes in equine spermatozoa throughout the cryopreservation process.

Chlortetracycline (CTC) fluorescence staining analysis was used to investigate cryopreservation-induced capacitation-like changes in equine spermatozoa. Freshly ejaculated spermatozoa were found to display a high proportion of F pattern cells (uncapacitated; 93.6%) and a lower proportion of B pattern (capacitated; 5.4%) and AR pattern (acrosome-reacted; 1%) cells. Following cryopreservation in modified Kenney's medium, capacitation-like changes were observed. There was a significant increase in the proportion of spermatozoa displaying the B pattern (64.8%; P<0.001) and AR pattern (32.8%; P<0.001), with a corresponding decrease in the proportion of spermatozoa displaying the F staining pattern (2.5%; P<0.001). Further analysis of CTC fluorescence staining patterns showed that there was a major decrease in the proportion of F pattern spermatozoa corresponding to an increase in B pattern spermatozoa following removal of seminal plasma after centrifugation and resuspension in freezing medium. There was a further decline in the proportion of F pattern spermatozoa, corresponding to increases in B and AR pattern spermatozoa, after the freezing and thawing steps. Resuspension of centrifuged spermatozoa in homologous seminal plasma did not induce capacitation-like changes. These data indicate that the process of freezing and thawing stallion semen induces capacitation-like changes in spermatozoa and that most of the change is brought about by removal of seminal plasma, with further changes induced by the actual freezing and thawing step.

Acrosome Reaction↗
PubMed2002

Production of lambs of predetermined sex after the insemination of ewes with low numbers of frozen-thawed sorted X- or Y-chromosome-bearing spermatozoa.

The fertilizing ability of sex-sorted frozen-thawed ram spermatozoa was assessed after insemination of mature Merino ewes at a synchronized oestrus. Ewes were inseminated into the uterus or utero-tubal junction (UTJ) with a total of 140 x 10(6) unsorted (control) or 2-4 x 10(6) sorted (X or Y) frozen-thawed ram spermatozoa 54 to 57 hours after removal of progestagen-impregnated pessaries and an injection of 400 IU of pregnant mare serum gonadotrophin (Folligon, Intervet). The spermatozoa were separated into X- and Y-chromosome-bearing spermatozoa after analysis with a modified high-speed cell sorter (SX MoFlo). The number of ewes pregnant after insemination with unsorted frozen-thawed spermatozoa was significantly higher (26/48; 54.3%) than for ewes inseminated with either X- (12/48; 25.0%) or Y-sorted spermatozoa (7/48; 14.6%) (P<0.05). Seventeen of the eighteen lambs produced by ewes inseminated with X-sorted spermatozoa were female (94.4%) and 8/8 lambs from ewes inseminated with Y-sorted spermatozoa were male (100%). The sex ratio of the lambs born to ewes inseminated with sex-sorted spermatozoa was significantly skewed from the 51.3% male and 48.7% female ratio in the control group (P<0.05). This study showed, for the first time, that lambs of predicted sex can be produced after insemination with low numbers of sex-sorted cryopreserved ram spermatozoa.

Abortion, Veterinary↗