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M Magistrini

Publications and source records attributed to M Magistrini.

30 records · Page 2Linked to original sources
PubMed1996

Effect of indole-3-acetic acid (plant auxin) on the preservation at 15 degrees C of boar semen for artificial insemination.

In order to extend the duration of boar sperm survival at 15 degrees C for artificial insemination, we tested the effect of indole-3-acetic acid (IAA), which appeared to be the main sperm protective substance present in the Coco nucifera endosperm (coconut water). Two IAA concentrations (10 and 100 ng/mL) in Beltsville extender (BTS) were studied for their in vitro effects. The motility, the percentage of motile spermatozoa and the acrosome morphology of sperm were recorded each day over 13 days of storage at 15 degrees C, after 5 min and 3 h of incubation at 39 degrees C. The IAA effect on sperm preservation was also studied in vivo at a concentration of 10 ng/mL in BTS by inseminating groups of females twice at 24 h intervals either at D0 (day of sperm collection) and D1 (D0/1) or at D5 and D6 (D5/6). At D0/1, the two groups of females (control and IAA) were inseminated with a total of 6.3 x 10(9) spermatozoa (3.15 x 10(9) at D0 and the same dose at D1) whereas at D5/6, on IAA group was inseminated with a total of 6.3 x 10(9) spermatozoa and another one with 12.6 x 10(9) spermatozoa. The animals in the D5/6 control group were inseminated each with a total of 12.6 x 10(9) spermatozoa. For each group of females (n = 106-140), fertility rate (% farrowing) and prolificacy rate (litter size) were recorded. No effect of IAA in vitro on the motility rate and on the percentage of motile spermatozoa was observed over a 13 day storage. However, IAA (10 ng/mL) had a significant positive effect on the percentage of living spermatozoa with intact acrosomes after 13 days (66 vs 54%, P < 0.05). The fertility and prolificacy rates after 5-6 days of sperm preservation in BTS extender alone did not differ significantly between D5/6 and D0/1 but the total number of inseminated spermatozoa was 12.6 x 10(9) at D5/6 instead of 6.3 x 10(9) at D0/1. When the spermatozoa were stored in the presence of 10 ng/mL IAA for 5-6 days at 15 degrees C, the fertility and prolificacy of the females inseminated with only 6.3 x 10(9) spermatozoa were identical to those of the females inseminated with an equal number of spermatozoa at D0/1 in the presence or absence of IAA.

Acrosome↗
PubMed1995

[Autoimmune asthenospermia induced by an epididymal protein, ovine prealbumin (oPES)].

The motility of ejaculated spermatozoa (% of progressive spermatozoa) has been evaluated visually on 26 adult rams. Half the animals were immunized with a secretory epididymal protein (prealbumin epididymal-specific (PES) ovine) injected according to immunizing protocols (Freund or Hunter adjuvant) intraperitoneally or intradermally (Freund or Hunter adjuvant) or intramuscularly (Hunter adjuvant or PES only). The other animals received the same product without the protein (controls). The product resulted in a strong asthenospermia which parallels the transient presence of anti-PES antibodies in the seminal plasma. A study with 64 ewes showed that the fertility of 10 immunized rams that had recovered sufficient forward motility to ensure fertilization, did not differ from that of control rams.

Animals↗
PubMed1991

Use of concanavalin A for coating the membranes of stallion spermatozoa.

Semen from three ejaculates from each of 4 stallions was frozen in liquid nitrogen. Morphology was evaluated by coating the spermatozoa with fluorescein-labelled Concanavalin A (FITC-ConA2) and motility was measured by computer-assisted image analysis. Coating was performed at each step of the freezing procedure (dilution, cooling, addition of glycerol and freeze-thawing) and observations were made after each step, to evaluate changes, or after subsequent steps, to determine protection provided by the coating method. All the parameters showed progressive changes during the freezing procedure. Mean track speed of the spermatozoa, the proportions of normal and motile spermatozoa and lateral head displacement all decreased, whereas the proportions of spermatozoa exhibiting non-fluorescence in the equatorial segment and wrinkled acrosome membranes increased. The results demonstrated that coating stallion spermatozoa with ConA2 provides some degree of protection for acrosome membranes and it helps to preserve motility after freezing and subsequent thawing.

Animals↗
PubMed1991

In vitro fertilization in the horse. A retrospective study.

Since the first successful collection of oocytes by non-surgical puncture, there have been numerous attempts to fertilize them but few segmented embryos have resulted. The latest attempts at follicular puncture (Palmer et al., 1987) provided 159 oocytes. Oocytes found broken (18%) were probably already broken, or at least fragile, before puncture. The 41 oocytes were fertilized only with semen treated with Ionophore A23187. Following ionophore treatment of semen, 16 ova segmented (of 113 inseminated oocytes) indicating fertilization, and another 7 showed signs of fertilization but not segmentation. Our basic protocol, when applied to 60 oocytes, yielded 11 (18%) embryos and 5 (8%) that were fertilized without segmentation. Modifications to the protocol produced no improvement in the results. Eight embryos fertilized in vitro were transferred into the ampulla of 8 recipient mares. One pregnancy resulted and foaling occurred June 14, 1990. This is the first equine pregnancy to continue to full term following in vitro fertilization.

Animals↗
PubMed1991

Maturation of oocytes from normal and atretic equine ovarian follicles as affected by steroid concentrations.

The ovaries of 23 mares were collected at slaughter during April-June and follicles (4-40 mm in diameter) were dissected and punctured to obtain oocytes for culture. The follicles were grouped according to histology: (a) normal, (b) showing primary and (c) secondary atresia. Antral fluid was analyzed for steroid content; oestradiol and testosterone (but not progesterone or androstenediol) were closely correlated with follicle size and histological state. Oocytes were cultured early after slaughter in Medium 199 (Difco OSI, France) or Medium B2, the highest percentage of oocytes reaching Metaphase 2 (53%) occurred after 36-38 h in culture. Among the 52 oocytes cultured and inseminated 1 case was confirmed with a 4-blastomere-like structure, 10 cases had structures resembling pronuclei, 9 oocytes were in Metaphase 1, 14 were in Metaphase 2 and 18 were degenerated.

Androstenedione↗
PubMed1987

Influence of season and frequency of ejaculation on production of stallion semen for freezing.

In an attempt to define optimal season and ejaculation frequency for frozen semen, semen was collected from 6 stallions (3 horses and 3 ponies) 3 times per week or every day, alternating every week, for 1 year. The semen was evaluated and frozen. All the samples were thawed at the end of the experiment. At collection, fresh semen evaluations showed that winter (as opposed to spring and summer) was associated with low sexual behaviour, small volumes of spermatozoa and gel, high sperm concentration and lower motility. The high ejaculation frequency yielded a decreased volume, concentration of spermatozoa in the ejaculate and slightly improved motility. The quality of thawed semen was analysed by video and microscope estimations for motility and by two staining methods for vitality. No variation was observed according to the ejaculation frequency; the best freezability was obtained in winter but the difference was small compared to between-stallion variability and optimization of frequency and season did not change a 'bad freezer' into a good one.

Animals↗
PubMed1987

Assessment of fertility and semen evaluations of stallions.

(1) Various estimations of motility (subjective appreciation, count on video record, Doppler laser apparatus and optic-microcomputer analyser) or percentage of live spermatozoa (eosin-nigrosin staining) showed a higher repeatability for measurements of a same sample than for straws of a same ejaculate: the values were high (respectively greater than 0.78 and greater than 0.69) except for the optical analyser and staining. (2) Semen samples were collected from 80 stallions 5 times at 24-h intervals. The repeatability varied from 0.37 to 0.69 for gel-free volume, concentration, total sperm number, % of motile spermatozoa in raw and extended semen at collection or after storage. Therefore, to assess a stallion, 2-7 ejaculates, according to the characteristic being measured, are needed to get a repeatability of 0.80 for the mean value. (3) A study on 79 stallions serving mares over 4-152 oestrous cycles per year showed that 17 seasons are necessary to measure fertility based on the pregnancy rate per oestrous cycle with the same accuracy. If they served more than 25 cycles every year, 6 seasons only were required. In both cases, it was less than for % of live foals per season.

Animals↗
PubMed1980

Effects of cold and of isopropyl-N-phenylcarbamate on the second meiotic spindle of mouse oocytes.

The meiotic spindle of ovulated mouse oocytes are cold sensitive similar to the mitotic spindles of somatic cells and unicellular organisms. On crushed ice, the spindle microtubules were disorganized between 15 and 60 min of treatment: continuous microtubules depolymerized at first, then kinetochore fibers followed. MTOCs also dispersed during the cold treatment while kinetochores remained intact. The effects of isopropyl-N-phenylcarbamate (IPC) on the reorganization of the meiotic spindle of mouse oocytes were studied after cold disorganization. This drug is an antimitotic agent which appears to act on cells lacking centrioles (higher plants, amoeba, alga) as oocytes do. In ovulated mouse oocytes, IPC disturbed microtubule orientation and the relative distance between MTOCs and chromosomes. However this herbicide did not seem to act on polymerized microtubules and its action was apparently reversible. The disturbances in microtubule orientation are probably due to the displacement of chromosomes and MTOCs, which are loci of microtubule polymerization.

Animals↗
PubMedDate not supplied

Preliminary observations in in vitro development of equine embryo after ICSI.

The objective of this study was to perform intracytoplasmic sperm injection (ICSI) on in vitro matured equine oocytes and to improve in vitro embryonic development on Vero cells after activation of the microinjected oocytes with calcium ionophore. After maturation (23 or 40 h, 38.5 degrees C, 5% CO2), the cumulus-oocyte complexes were denuded, centrifuged and all oocytes exhibiting the first polar body were microinjected. ICSI was performed using fresh semen from three fertile stallions. Microinjected oocytes were activated with calcium ionophore A23187 (10 min, 10 microM) and cultured individually for 7 days on Vero cells in microdrops. In seven trials, 353 cumulus-oocyte complexes were matured and 103 oocytes were microinjected. Eight oocytes were sham microinjected. After ICSI, 85 oocytes (82.5%) survived the sperm injection procedure. Among the 76 successfully microinjected oocytes, 52 (68%) were fertilized (two pronuclei, syngamy stage and cleaved ova). Sham microinjected oocytes were not activated. After in vitro culture, 35 ova (46%) were cleaved 2 days after ICSI and early embryonic development was obtained (three embryos of 23 cells, 50 cells and more than 80 cells) 5 to 7 days after ICSI.

Animals↗
PubMedDate not supplied

Secular sperm trends in stallions between 1981 and 1996.

Several reports have suggested that human semen quality has declined throughout the world over the last few decades. Chemicals in the environment acting as endocrine disrupters have been implicated as a possible cause. If this is indeed the case, then similar effects may be observed in animals. We analyzed 1489 ejaculates collected from 390 Breton draught stallions between 1981 and 1996. Semen was collected from all the stallions at a single center, according to standardized semen collection protocols and laboratory methods. Semen volume decreased slightly but significantly and there was an increase in sperm concentration over the study period. However, total sperm production was unchanged. Seminal fluid volume is controlled by accessory sex glands, which are regulated by androgens. Chemicals with antiandrogenic properties have been detected in the environment. By affecting the development or function of accessory sex glands, these chemicals may be at least partly responsible for the observed decrease in semen volume.

Animals↗