Hamster Ova Research Articles

Fertilization of hamster ova by human spermatozoa in relation to other semen parameters.

Different indices of the zona-free hamster ovum test system were interrelated. High correlations were found between the fertilization percentage and the average number of penetrated spermatozoa/ovum (r = 0.99) and between the fertilization percentage and the number of spermatozoa attached to the ova surfaces (r = 0.72). Fertilization percentages from 63 subfertile patients were correlated with different semen factors assessed by multiple exposure photography (MEP). Low correlations were found between sperm concentration and fertilization percentage (r = 0.29) and between fertilization percentage and motile sperm count (r = 0.33). Spermatozoa progressing with high average velocity had low fertilization rates compared to specimen with moderate average velocity. Effects of sperm washing on the in vitro fertilizing capacity were studied in a group of 40 subfertile men. The fertilization percentages of 8 specimens--with visual seminal plasma abnormalities--increased significantly when immediate dilution of semen was applied.

Zinc does not inhibit the capacitation of human spermatozoa in vitro

AbstractThe effects of zinc on human sperm motility, fertilizing capacity (as assessed by penetration of human spermatozoa into the zona pellucida‐free hamster oocyte), and nuclear chromatin decondensation were investigated using spermatozoa from four fertile donors. Both sperm motility and the penetration of sperm into zona‐free hamster ova were consistently impaired in media containing 1,000 μM zinc. Spermatozoa from one man were similarly affected at a concentration of 500 μM zinc, but no adverse effects were noted at this zinc concentration in experiments with other donors. Since decreased fertilizing capacity in response to zinc was always accompanied by a significant decline in both the percentage of motile cells and mean swimming speeds, it appears that all of these results reflect a general toxic effect on the cells. At lower concentrations (125–250 μM), zinc had no effect on human sperm motility nor their ability to undergo capacitation and penetrate zona‐free hamster ova in vitro. For some donors, zinc (125–500 μM) stimulated both the attachment of spermatozoa to the hamster vitellus and the incorporation of spermatozoa into the hamster ooplasm. The decondensation of human sperm nuclear chromatin in sodium dodecyl sulfate was largely inhibited when zinc was added to the medium, but no significant changes in nuclear stability were apparent after capacitation in zinc‐free medium. We conclude that zinc, when present in subtoxic concentrations, does not adversely affect the ability of human spermatozoa to undergo capacitation and penetrate zona‐free hamster ova in vitro.

Temperature dependence of capacitation in bat sperm monitored by zona‐free hamster ova

AbstractThe temperature dependence of capacitation in bat sperm (Myotis lucifugus lucifugus) was studied by monitoring fertilizations rates of zona‐free hamster ova at different temperatures. Spermatozoa were cultured in BWW medium at temperatures 4°C, 24°C, 32°C, 42°C, and 55°C from 0–24 hr. Activation of sperm could be determined visually due to the change in movement seen through light microscopy. Activation was later confirmed by higher rates of fertilization. Preincubation of the bat sperm was found to have a direct effect on the success of penetration of the zona‐free hamster ova. Holding bat spermatozoa at low temperature for long intervals allowed them to remain motile but unable to fertilize. Sperm are not irreversibly damaged, however, and activation, when the temperature is increased to 32°C, is faster than when sperm are intitially put at 32°C, resulting in good fertilization rates.

Penetration of zona-free hamster ova by bull sperm after frozen storage

Penetration of zona-free hamster ova by bull sperm after frozen storage

Fertilization of squirrel monkey and hamster ova in the rabbit oviduct (xenogenous fertilization).

Homologous sperm and ova of either squirrel monkeys or hamsters were placed in the oviducts of pseudopregnant rabbits. Xenogenous fertilization rates of 36 and 60 percent were obtained for squirrel monkey and hamster gametes, respectively.

A Dose-Response Relationship between Chromosome Aberrations and Hypoxic Insults in Overripened Hamster Ova

An attempt was made to analyze the quantitative occurrence of chromosome anomalies by the exposure of slightly overripened ova (delayed fertilization) to hypoxic insults in golden hamsters. Three groups were established: (1) a control group (PO2 = 152 mmHg); (2) a 4,500 m altitude group (PO2 = 87 m5 hr post-ovulatory aging revealed no striking effect on reproductive performance, as well as on the production of chromosome aberrations. Nervertheless, even in a slightly overripened condition ovum increased in susceptibility to the production of chromosome anomalies after hypoxic exposure equivalent to 4,500 m altitude. The dose-response relationship between hypoxia and the occurrence of triploidies was particularly distinguished. On the other hand, a similar relationship was not so evident in the production of aneuploidies, especially of trisomies. It can, therefore, be surmised that the change in the cytogenetic milieu at the time of the second polar body extrusion has some quantitative relation to the severity of environmental stressors.

The Use of Zona-Free Animal Ova as a Test-System for the Assessment of the Fertilizing Capacity of Human Spermatozoa

The zona-free hamster ovum was evaluated as a substitute for human o va in the assessment of the fertilizing capacity of human spermatozoa. Zona-intact ova completely resisted sperm penetration. Using nonpreincu bated spermatozoa sperm penetration of zona-free ova began 4-5 hours after insemination. However when spermatozoa were preincubated in a modified Krebs-Ringer solution for 4 hours sperm penetration began within 1 hour. There is some evidence that this is associated with the completion of sperm capacitation and the acrosome reaction. The results suggest that zona-free hamster ova can be substituted for human ova in the preliminary assessment of the fertilizing capacity of human spermatozoa.

FERTILIZATION IN SWINE AND CATTLE

Fertilization and its prerequisites, i.e. sperm transport, capacitation and oocyte maturation, were discussed with emphasis on the occurrence of these processes in the pig and cow. Attempts to fertilize porcine and bovine ova in a micro-droplet system which was used successfully to fertilize mouse and hamster ova were not successful. Many droplets contained highly motile spermatozoa which were effective in removing the follicular cells from around the zonae. Spermatozoa attached to the zonae but did not penetrate the ova in vitro. No motile bull or boar spermatozoa with an "acrosome reaction" were observed in the droplets. When droplets which contained boar spermatozoa and pig follicular oocytes for 4 h were transferred into the oviducts of estrous females, spermatozoa exhibited acrosome reactions and ova were penetrated. Reducing oocyte maturation time and injecting progesterone before ovulation increased (P < 0.05) the incidence of polyspermy in pigs. Bovine oocytes underwent maturation and were penetrated by bull spermatozoa in pig oviducts. Culture systems, other than the oviduct, did not provide satisfactory conditions for fertilization of bovine or porcine ova.

Spontaneous Activation of the Hamster Eggin vivo

Spontaneous activation of the hamster ovum is a normal occurence in oviducal eggs that are not inseminated. Many aspects comprising this process of parthenogenesis mimic events characteristic of fertilization and include for example, the formation of the second polar body and the development of one or two pronuclei. Occasionally the activated egg cleaves to form a two-cell stage. The similarity between the spontaneously activated hamster ovum and the inseminated egg has been previously documented at the light microscopic level of investigation; however, further investigation is warranted for the study of parthenogenesis in mammals provides an opportunity of elucidating developmental mechanisms of the fertilized egg. Accordingly, unfertilized eggs were flushed from the oviducts of hamsters at different intervals during the estrus cycle (6 to 70 hours postovulation), prepared for light and electron microscopy, and compared with fertilized eggs obtained at corresponding periods.

Time and process of sperm penetration into hamster ova in vivo and in vitro.

Time and process of sperm penetration into hamster ova in vivo and in vitro.