Hypoosmotic swelling test of sperm

For the diagnosis and evaluation of the therapy for male infertility and for predicting the outcome of AIH and IVF-ET, technically simple, replicable tests that can be performed virtually anywhere and that have definite reliability are required. The results of the HOS test correlate well with the functions of the sperm cell membrane, indicating such aspects as motility, and it is thought to be a particularly effective test of human sperm fertility. Because the HOS test reflects the functions and integrity of the sperm cell membrane, it should be possible to use it to predict the potential for fertilization of frozen sperm.

[Pathologic oocytes within the scope of in vitro fertilization]

Data of 67 patients, in whom 114 inseminated oocytes with morphological abnormalities were registered by means of light microscopy, were compared with those of a control group consisting of 69 patients where in vitro fertilization (IVF) proved successful. Significant correlations were found between certain parameters of the IVF attempt and the appearance of the described pathological changes in the oocytes. A significantly higher incidence of oocyte pathology was found with elevated progesterone and also LH values during the follicular phase. With a great number of follicles and in the case of small-sized follicles there were significantly more pathological ova--both degenerated and pathologically fertilized. A good oestrogen increase after ovulation induction with human chorionic gonadotrophin (HCG) was associated with fewer morphological abnormalities of the inseminated oocytes. When spermatozoa with lower total motility (less than or equal to 40%) or an increased percentage of pathological forms (greater than 60%) were used for IVF, significantly more pathological oocytes appeared. A pathological spermiogram was noticeably correlated with an increased occurrence of a solitary decayed nuclear structure of the mature ovum. The significance of these connections and a hypothesis of the development of the described nuclear structure are discussed.

Normal fertilization in men with high antibody sperm binding by the addition of sufficient unbound sperm in vitro

A high incidence of fertilization failure has been reported in men with over 70% of their sperm bound with isoantibodies. In three men with greater than 80% antisperm antibody binding with IgG and IgA immunoglobulins, a normal rate of fertilization (29/46 oocytes; 63%) was achieved by adding a sufficient number of motile sperm to provide at least 50,000 unbound sperm per oocyte. This method appears to be simpler and more effective than attempting to separate unbound sperm in vitro.

Human in vitro fertilization in couples with unexplained infertility and a poor postcoital test

The results of in vitro fertilization (IVF) with the husband's semen were compared in 3 groups of fully investigated infertile couples. In those with tubal infertility (n = 43) 194 out of 273 (71.1%) oocytes were fertilized, at least 1 oocyte being fertilized in 42 of the 43 couples (97%). In couples with unexplained infertility and a 'good' postcoital test (PCT) (n = 9), 39 out of 64 (61.5%) oocytes were fertilized in 8 of the 9 (88%) couples. In couples with unexplained infertility and a 'poor positive' PCT despite normal semen analysis, 16 out of 44 (36.3%) oocytes were fertilized in 5 of the 6 (83%) couples. These results show a good correlation between in vivo sperm penetration of cervical mucus and human IVF in couples with unexplained infertility.

Microtubules and specification of the dorsoventral axis in frog embryos

The body plan of the frog is set-up by a rearrangement of the egg cytoplasm shortly after fertilization. Microtubules play several roles in this critical developmental event.

Induction of bovine sperm capacitation by TEST-yolk semen extender

Ejaculated bull semen was diluted 1:10 in the TEST-yolk buffer, cooled slowly to 4 degrees C, and stored for up to 48 h. Aliquots were taken at 0, 4, 8, 16, 24, and 48 h and washed once or three times in bovine serum albumin-saline and the sperm pellets resuspended in this saline. Fertilization of zona-free hamster oocytes was used to assess sperm capacitation. Motility differed between samples washed once or three times (53.7 vs. 21.7%). Motility was highest at 4 h storage but did not differ between 16, 24, or 48 h of storage. More sperm without intact acrosomes were found at 4 h than at 0 h, but the percentage did not change further until after 24 h. Penetration of oocytes was not different between sperm washed once or three times (28.5 vs. 26.9%). No penetration occurred at 0 h, and highest penetration rates occurred at 4 and 8 h of storage (32.1 and 33.4%). Penetration rates at 16, 24, and 48 h were not different (25.3, 25.2, 22.5%). In conclusion, storage of bull sperm in TEST-yolk buffer for 4 to 48 h resulted in capacitation. Even though capacitation was induced by 4 h, at least 71% of the sperm population had not undergone an acrosome reaction by 48 h of storage. This may explain why penetrability was maintained over this period.

Human sperm--egg interactions and their disorders: implications in the management of infertility

The present era of infertility management is characterized by an increasing interest in defects of sperm--egg interactions. When the spermatozoon meets the egg, it must first react with the enveloping coat which controls sperm access to the cell surface of the oocyte. Adequate sperm motility is a major condition for penetration through the egg investments. The ability of spermatozoa to respond to physiological stimuli by a timely acrosome reaction is another necessary prerequisite for this event, as well as for sperm fusion with the oocyte. The clinical significance of current laboratory tests evaluating different aspects of gamete function is discussed and a practical guide is given for their indication and interpretation and for the use of their results in choosing rational therapy.

Hypoosmotic swelling test in the prediction of male fertility

The hypoosmotic swelling test (HOS) is a simple test to measure the functional competence of human sperm membranes. The question is, does a relationship exist between this competence and the fertilization potential of human spermatozoa? In this study the strongest correlation (r = 0.76) was obtained between sperm swelling and sperm viability (supravital staining). Only a moderate correlation (r = 0.50) was obtained with normal sperm morphology; weaker correlations were also obtained with the sperm penetration assay (r = 0.42) and human IVF (r = 0.24). The results, therefore, indicate that the HOS test has a limited predictive value. Notwithstanding this low concordance between sperm swelling and fertilizing potential, a less than 50% HOS test threshold was seen to be a definite indicator of a male factor.

Usefulness of sperm penetration assay in fertility predictions

The competence of the sperm penetration assay (SPA) to predict male fertility, as determined by normal sperm morphology and the fertilizing potential, as shown by human in vitro fertilization (IVF), was investigated. A significant correlation was obtained between normal sperm morphology and the SPA (phi = 0.623). A weaker correlation was however obtained with human IVF (phi = 0.397). Notwithstanding this weak association, a positive SPA (greater than 10%) was highly predictive (95%) of human IVF success. In contrast, a negative SPA (less than or equal to 10%) was associated with a high rate of false-negatives (65%). The SPA does however warn that a male factor may be present, as the mean fertilization rate of this group of patients was markedly reduced. The preincubation period for the spermatozoa did not play a major role in the predictive ability of a SPA outcome.

Interpretation and misinterpretation of semen parameters

Semen analysis, which is traditionally used to evaluate male fertility, may be misleading if sample is lost or inadequately mixed. A short or excessive abstinence period may cause a low count or a high count with low motility. Damage from low temperature or delay in evaluation may decrease the reported motility. Computer-assisted semen analysis has eliminated some of the variability and has allowed the evaluation of other sperm motion variables such as sperm velocity, linearity, maximum and mean amplitude lateral head displacement, and beat-cross frequency. These measurements may also occasionally be misleading. Other tests may give a better indication of the function of sperm. The hamster egg penetration test has been used but is technically difficult, and perhaps that is why there is controversy as to the clinical value of the test in predicting subfertile sperm despite normal conventional semen analysis. Some recent data suggest that the hypo-osmotic swelling test, which determines the functional integrity of the sperm membrane, may be the appropriate prognosticator. There is a need for further studies to define the best method to determine whether a male factor is responsible for a couple's infertility.

A free calcium wave traverses the activating egg of the medaka, Oryzias latipes

Aequorin-injected eggs of the medaka (a fresh water fish) show an explosive rise in free calcium during fertilization, which is followed by a slow return to the resting level. Image intensification techniques now show a spreading wave of high free calcium during fertilization. The wave starts at the animal pole (where the sperm enters) and then traverses the egg as a shallow, roughly 20 degrees-wide band which vanishes at the antipode some minutes later. The peak free calcium concentration within this moving band is estimated to be about 30 microM (perhaps 100-1,000 times the resting level). Eggs activated by ionophore A23187 may show multiple initiation sites. The resulting multiple waves never spread through each other; rather, they fuse upon meeting so as to form spreading waves of compound origin. The fertilization wave is nearly independent of extracellular calcium because it is only slightly slowed (by perhaps 15%) in a medium containing 5 mM ethylene glycol-bis[beta-aminoethyl ether]N,N'-tetraacetic acid (EGTA) and no deliberately added calcium. It is also independent of the large cortical vesicles, which may be centrifugally displaced. Normally, however, it distinctly precedes the well-known wave of cortical vesicle exocytosis. We conclude that the fertilization wave in the medaka egg is propagated by calcium-stimulated calcium release, primarily from some internal sources other than the large cortical vesicles. A comparison of the characteristics of the exocytotic wave in the medaka with that in other eggs, particularly in echinoderm eggs, suggests that such a propagated calcium wave is a general feature of egg activation.