Showing papers on "Sperm published in 1976"
TL;DR: 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.
Abstract: 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.
871 citations
TL;DR: In double mating experiments with Drosophila melanogaster in which one male had been irradiated, it was confirmed that sperm displacement is extensive, i.e. the second male to mate displaces most of the previously‐stored sperm.
Abstract: 1
In double mating experiments with Drosophila melanogaster in which one male had been irradiated, it was confirmed that sperm displacement is extensive, i.e. the second male to mate displaces most of the previously-stored sperm.
2
The predominance of the second ejaculate over the first increases with the interval between the two matings, from about P2= 0.83 (second mating on the first day after the first mating) to about P2= 0.99 (interval between mating = 14 days) where P2 is the proportion of offspring fathered by the second male.
3
A more accurate method for calculating P2 values is developed for experiments in which sperm are ‘labelled’ by irradiation treatment (equation 1).
4
Observations of the reducing egg production of the female throughout life were also obtained. A model is examined which incorporates both the sperm competition and egg production data to predict the reproductive value to a male of a mating with a given type of female, varying in age and mating status. The relative value (in terms of probable numbers of progeny gained) of a mating with a virgin or 4 day post-mating female is about twice that of a 14 day post-mating female, mainly because of the fecundity difference.
5
Some evolutionary aspects of sperm competition and multiple mating in insects are reviewed and discussed.
363 citations
TL;DR: The results show that sperm nuclei are stable organelles and that the factors in egg cytoplasm which control the transformation of spermuclei into male pronuclei are not restricted to a particular species.
Abstract: Hamster eggs were injected with either isolated nuclei of hamster sp ermatozoa or fresh frozen-thawed and freeze-dried human spermatozoa to determine whether they could develop into male pronuclei. Each of the specimens were capable of devloping into male pronuclei when injected. The results show that sperm nuclei are stable organelles and that the factors in egg cytoplasm which control the transformation of sperm nuclei into male pronuclei are not restricted to a particular species.
360 citations
TL;DR: The results indicate that canine ovarian oocytes can be matured in vitro, the spermatozoa require capacitation which takes approximately seven hours in vitro and maturation of the oocytes is not required for sperm passage through the zona pellucida or entry into the vitellus nor for sperm nuclear decondensation.
Abstract: Canine ovarian oocytes were cultured in a medium consisting of TC medium 199, fetal calf serum and antibiotics. Ninety-nine percent of the apparently healthy oocytes were in the germinal vesicle (dictyate) stage when recovered from the ovaries; 25% of them reached metaphase I or II by 72 hours of culture. Washed ejaculated spermatozoa were added to BWW medium containing oocytes which had either been removed directly from the follicles or which had been cultured for 24--72 hours. The earliest acrosome reaction and zona penetration by spermatozoa were seen at seven hours after insemination. Seventy-four percent of the oocytes examined between 11 and 24 hours after insemination showed evidence of zona penetration by spermatozoa. Neither the condition of the oocyte vitellus nor the stage of nuclear maturation influenced the incidence of zona penetration. Decondensing sperm nuclei were found in the vitellus of 27% of the oocytes which had not been cultured and in the vitellus of 20% of those which had been cultured for 24--72 hours and were in various stages of maturation. These results indicate that (1) canine ovarian oocytes can be matured in vitro, (2) the spermatozoa require capacitation which takes approximately seven hours in vitro and (3) maturation of the oocytes is not required for sperm passage through the zona pellucida or entry into the vitellus nor for sperm nuclear decondensation.
221 citations
TL;DR: The results indicate that sperm matures within the epididymis of this species within 5 days, even though a 265-fold difference in epidodymal reserves was found.
Abstract: Experiments were performed to establish the daily level of testicular production of spermatozoa the distribution of spermatozoa within the epididymis and the time required for transport of spermatozoa through the epididymis in 8 sexually rested rhesus monkeys (Macaca mulatta) of at least 6 years of age. The daily production of spermatozoa was similar among all animals averaging a production rate of 23 times 10 (6) sperm/gm of testicular parenchyma per day. However the weight of testicular parenchyma ranged from 15 to 32 gm. Per testis the average daily spermatozoal production was found to be 547 plus or minus 69 tomes 10(6). Consequently the normal average production of spermatozda for the rhesus monkey per day during the breeding seasson is about 1.1 times 10(9). The number of sperm in the caput corpus and cauda epididymis was found to be .6 plus or minus .1 2.1 plus or minus .3 and 2.9 plus or minus .3 times 10(9) respectively. 1 plus or minus .1 times 10(9) sperm were found in the proximal 49-70 mm of the ductus deferens. The mean transport times of sperm through the caput corpus and cauda epididymis were approximately 1.1 3.8 and 5.6 days respectively. The rate of transport of sperm through the epididymis was virtually the same between 2-5.5 days even though a 265-fold difference in epididymal reserves was found. The results indicate that sperm matures within the epididymis of this species within 5 days.
217 citations
TL;DR: The diluent proved to be a favourable medium for significantly delaying the deterioration of sperm progression over a 24-hour period and yielded sperm suspensions free of seminal plasma and populations of spermatozoa that had increased motility ratings compared with the original semen.
211 citations
TL;DR: Golden hamster eggs at various stages of maturation, fertilization, and early development were freed from the zona pellucida and inseminated in vitro with capacitated, acrosome-reacted spermatozoa.
210 citations
TL;DR: Ionophore A23187 should prove an experimentally useful drug for further study of the acrosome reaction since its effect on cells is understood, it induces synchronous reactions in a high percentage of sperm, and it conveniently reduces the capacitation interval in mammalian sperm.
Abstract: The role of Ca+2 in the acrosome reaction of echinoid and mammalian sperm was investigated using the Ca+2 transporting ionophore A23187. The ionophore induced morphologically normal acrosome reactions in both types of sperm (as assessed by electron microscopic observation of echinoid sperm and phase contrast microscopic observation of mammalian sperm). In echinoids, these reactions were immediate. In the guinea pig and hamster, ionophore significantly decreased the capacitation interval; early reactions were accompanied by activation of motility. Ionophore induced reactions were affected by sperm, ionophore and Ca+2 concentrations. Since both ionophore induced and natural reactions require extracellular Ca+2, it is suggested that an influx of Ca+2 represents the initial step of the acrosome reaction. Under natural conditions, the permeability change which results in Ca+2 influx may be induced in echinoid sperm by egg jelly and may occur in mammalian sperm during capacitation. Ionophore A23187 should prove an experimentally useful drug for further study of the acrosome reaction since its effect on cells is understood, it induces synchronous reactions in a high percentage of sperm, and it conveniently reduces the capacitation interval in mammalian sperm.
191 citations
TL;DR: The hypothesis is introduced that the shaking phenomenon is due to an interaction between sensitized spermatozoa and the glycoprotein micelles in cervical mucus and not after contact with the aqueous fraction.
173 citations
TL;DR: In an in vitro assay human spermatozoa penetrated the zona pellucida of 38.8% of 773 human oocytes recovered from the ovaries of cadavers as mentioned in this paper.
149 citations
TL;DR: An account of gonadogenesis in the normal male and in a mutant that is a temperature-sensitive sex transformer is provided, which transforms an XX hermaphrodite into a phenotypic male, complete with a normal male gonad and vestigial external genitalia.
TL;DR: Sperm output was reduced in stressed boars during weeks two through six of treatment and sperm volume and gel weigh per ejaculum were not altered during elevated ambient temperature, however, sperm motility and percent normal cells with non-aged acros'omes decreased and the percentage of abnormal cells and cells with aged acrosomes increased by the second week of treatment.
Abstract: SUMMARY Twelve Yorkshire boars were randomly as- signed to one of two temperature controlled chambers to determine the influence of ele- vated ambient temperature on reproductive performance. Heat stressed boars were exposed to 34.5 -+ 1.0 C for 8 hr and 31.0 + 1.0 C for 16 hr daily for 90 days. Control boars were maintained at 23.0 -+ 1.0 C throughout the experimental period. Semen was collected twice weekly to determine sperm output and quality. Semen volume and gel weigh per ejaculum were not altered during elevated ambient tempera- ture. However, sperm motility and percent normal cells with non-aged acros'omes decreased and the percentage of abnormal cells and cells with aged acrosomes increased by the second week of treatment. Sperm output was reduced in stressed boars during weeks two through six of treatment. Only 28.6% of 77 gilts bred with semen from stressed boars conceived compared to 41.2% of 88 gilts bred with control semen. At day 30 + 3 of pregnancy, embryonic survival was 71.2 + 3.7% in gilts bred with semen from control boars and 48.5 + 5.2% for gilts bred with semen from stressed boars. (Key Words: Boar, Heat Stress, Semen, Sperm Morphology, Swine Reproduction.) 2Journal Article No. 3009 of the Agricultural Experiment Station, Oklahoma State University, Still- water, Oklahoma. This research was conducted in cooperation with the U.S.D.A., Agricultural Research Service, Southern Region. UAppreciation is expressed to Dr. R. K. Johnson and L. D. Young for assistance with the statistical analyses. 3Department of Animal Sciences and Industry, Oklahoma State University, StiUwater 74074. *Present address: Department of Animal Science,
TL;DR: The mouse spermatid nucleus becomes resistant to sonication at step 12, resistant to digestion by trypsin-DNase at step 15 and resistant to lysis by SDS between the testis and the caput epididymis, correlated with changes in the basic nuclear proteins.
TL;DR: It is concluded that during epididymal passage sperm develop from a cell physically unresponsive to changes in cAMP concentration to a form which initiates progressive motility upon changes incAMP concentration.
TL;DR: Results suggest that a trypsin-like enzyme (possibly acrosin) plays a role in the acrosome reaction in hamster sperm capacitated by bovine follicular fluid.
Abstract: Acrosome reactions occurring in vitro in hamster sperm capacitated by bovine follicular fluid were severely inhibited by four synthetic trypsin inhibitors and by Zn2 +. Three polypeptide trypsin inhibitors and a synthetic chymotrypsin inhibitor did not inhibit the acrosome reaction, and Ca2 + overcame the inhibition by Zn2. These results suggest that a trypsin-like enzyme (possibly acrosin) plays a role in the acrosome reaction.
TL;DR: Their amino acid compositions indicate that the protamines of eutherian mammals are coded by a C-rich genome which has been unusually susceptible to genetic drift, and an especially high rate of G leads to A transitions seems to have occurred in the human protamine genes.
TL;DR: Findings suggest that there are marked similarities between the acrosomal reaction in sea urchin sperm and membrane fusion dependent secretory processes in other cell types.
TL;DR: In vitro test system concluded that the fertilization envelope blocks sperm entry in Xenopus laevis, and isolated FE's proved impenetrable.
TL;DR: The DNA content of individual sperm from populations of acriflavine‐stained cells was investigated by analysis of fluorescence frequency distributions obtained with high‐resolution flow‐systems instruments, indicating that the lateral extension can be eliminated by controlling the sperm orientation with planar flow conditions or by accounting for sperm orientation by means of orientation sensing.
Abstract: The DNA content of individual sperm from populations of acriflavine-stained cells was investigated by analysis of fluorescence frequency distributions obtained with high-resolution flow-systems instruments. Sperm with spherical or cylindrical heads from three mollusk species produce narrow, symmetric fluorescence distributions. Flat sperm heads from six eutherian species produce asymmetric distributions consisting of a peak with a lateral extension to higher fluorescence values. The unexpected shape of these distributions was shown to be due to the flat geometry and high refractive index of the sperm heads in conjunction with the orthogonal axes of flow, excitation, and detection in the flow-systems instruments. The theoretical and experimeytal results indicate that the lateral extension can be eliminated either by controlling the sperm orientation with planar flow conditions or by accounting for sperm orientation by means of orientation sensing.
TL;DR: These studies revealed marked differences in steroid profiles of fluids entering and leaving the epididymis and of infertile testicular and fertile cauda epidIDymal sperm.
Abstract: Ten steroids which may have a role in the process of sperm maturation within the epididymis were quantified by competitive protein binding or radioimmunoassay. Rete testis fluid (RTF) carrying testicular sperm into the epididymis was rich in dehydroepiandrosterone and testosterone (21 ± 2 and 33 ± 3 ng/ml) while cauda epididymal plasma (CEP) around sperm which have completed maturation had high levels of progesterone, dihydrotestosterone, 3β-androstanediol, dehydroepiandrosterone and testosterone (7.4 ± 0.8, 20.3 ± 1.1, 6.5 ± 0.4, 8.0 ±0.7 and 11.5 ± 0.7 ng/ml). About 4 μg of steroids enter the epididymis daily in RTF, but <1% was found in CEP; the balance presumably was absorbed by the epithelium in the proximal caput epididymidis. Nevertheless, tissue levels of total 17β-OH androgens were lower in the proximal caput than in the distal caput or corpus epididymidis. In all zones of the epididymis, dihydrotestosterone accounted for about 70% of the total 17β-OH androgens found in the nuclear fraction. In t...
TL;DR: The eggs of Xenopus laevis are capable of initiating spindle formation and cleavage in response to microinjection of partially purified components of sea urchin sperm, suggesting the centriole and basal plate as the active materials.
TL;DR: An integrating microinterferometer was used to measure the dry mass of sperm heads, and the measurements suggest that many of the spermatozoa with two quinacrine-fluorescent spots are not YY-bearing, as previously thought, but might be incompletely condensed Y-bearing spermatoozoa.
Abstract: An integrating microinterferometer was used to measure the dry mass of sperm heads. The dry mass was found to be proportional to DNA content, and thus provides a useful method of estimating sperm DNA content. Using this technique we have confirmed that human spermatozoa which show none and one quinacrine-fluorescent spot are X- and Y-bearing respectively. However, the measurements suggest that many of the spermatozoa with two quinacrine-fluorescent spots are not YY-bearing, as previously thought, but might be incompletely condensed Y-bearing spermatozoa.
TL;DR: The substitution of fructose for glucose in Whittens medium resulted in very low fertilization rates similar to those found when glucose was omitted from the medium, indicating the possibility that the failure of fructose to support fertilization probably involves deficiencies in its transport or intracellular metabolism to provide adequate energy for sperm motility and capacitation.
Abstract: The requirements for glucose lactate and pyruvate which are present in Whittens medium for fertilization of mouse ova in vitro by epididymal sperm were examined to determine to what extent fertilization occurred when complete medium was used when all energy sources were omitted and when the only energy source was glucose (5.55 mM) or fructose (5.5 mM). The possibility that pyruvate was also requir ed for sperm capacitation was determined by examining the effect of preincubating the sperm in media with and without pyruvate upon their subsequent ability to fertilized ova. A possible effect of sodium lactate on sperm capacitation was examined by removing ova at various times after mixing with sperm to observe any differences in the proportion of ova fertilized in Whittens medium with or without sodium lactate and with pyruvate and glucose. Capacitation of sperm during a 3-hour preincubation period occurred equally well in complete medium and in medium from which lactate and pyruvate ahd been omitted. Glucose is thus the major source of energy for capacitation of epidiymal mouse sperm but the presence of cumulus cells or pyruvate is required to maintain ova viability during the incubation with sperm. The substitution of fructose for glucose in Whittens medium resulted in very low fertilization rates similar to those found when glucose was omitted from the medium. Measured rates of carbon dioxide production in this situation indicates the possibility that the failure of fructose to support fertilization probably involves deficiencies in its transport or intracellular metabolism to provide adequate energy for sperm motility and capacitation.
Journal Article•
TL;DR: The in utero effects of DES (Diethylstilbestrol) on the human male genital tract are reported in this follow-up study of male offspring of DES-treated mothers.
Abstract: At the Chicago Lying-In Hospital in the early 1950s gradually increasing doses of diethylstilbestrol (DES) were administered to 840 women beginning during the 10th-20th week of gestation with 5 mg/day and increasing by 5 mg every 2nd week to a maximum daily dose of 150 mg by the 34th week. Placebos were given to 806 women. There were 134 DES-esposed and 110 placebo-exposed male offspring who have been traced and evaluated. Of these now 21-23 year old men 89% were Causasians 10% Negro and 1% Oriental. The DES-exosed men had a significantly (p less than .05) higher incidence of epididymal and testicualr abnormalities than the unexposed controls. In 17 DES-exosed patients cystic masses in the area of the superior epididymis were aspirated. A straw-colored fluid without spermatozoa was found in 6 cases and a milky fluid containing sperm was found in 3. A cyst excised and studied histologically was lined with columnar epithelium without secretory cells or spermatozoa. Aspriation of similar masses in 2 control patients revealed spermatozoa in only 1. Cytologic examination of urine specimens and prostate fluids were similar in the 2 groups. Age of puberty and sexual functions were comparable. Circulating blood hormones assayed were the same. 1 DES-exposed patinet had bilateral hypotrophic testes azoospermia decreased plasma testosterone elevated plasma ICSH elevated follicle stimulating hormone and ennuchoid body habitus. Semen analyses showed a sperm density and fewer mobile spermatozoa in the DES-exposed cases. Sever pathologic blood changes were observed in 29% of 28 DES-exposed males and none in 18 control males. Genital abnormalities were found in 15 of 28 (53%) of the DES-ex posed group and 5 of 18 (25%) in the control group. Results show that transplacental effects of DES on the human male do occur. There may be considerable effect on spermatogensis and possibly on sperm maturation. Malignant cells were not found in any tissue or fluid.
TL;DR: Experiments on the process of ovum penetration by fresh and capacitated sperm lent weight to the hypothesis that capacitation and the acrosomal reaction are required for zona penetration and sperm-egg fusion.
Abstract: A mechanical technique for removal of zonae from mouse ova was devel oped to study its role in fertilization. The method involved the aspiration of oocytes in and out of small bore micropipettes. Exposure of oocytes to proteolytic enzymes resulted in reduced sperm penetrability compared intact zonae or mechanically denuded controls. However mechanically denuded ova demonstrated significantly (p less than .001) higher levels of penetration and polyspermy. Unfertilized me chanically denuded ova were morphologically similar to tubal oocytes. Within 1 hour after exposure to sperm cortical granules in unfertilized ova disappeared and denuded polyspermic zygotes showed formation of multiple pronuclei 4 hours after insemination. Experiments on the process of ovum penetration by fresh and capacitated sperm lent weight to the hypothesis that capacitation and the acrosomal reaction are required for zona penetration and sperm-egg fusion.
TL;DR: Female guinea-pigs were naturally or artificially inseminated before or after ovulation and the distribution of spermatozoa in the oviducts and the time of sperm penetration into the eggs were determined.
Abstract: Female guinea-pigs were naturally or artificially inseminated before or after ovulation and the distribution of spermatozoa in the oviducts and the time of sperm penetration into the eggs were determined. When animals were inseminated before ovulation, the spermatozoa stayed in the distal half of the oviduct until about the time of ovulation. Only a very few spermatozoa were present in the proximal half of the oviduct at the time of ovulation, but these were sufficient to effect fertilization. When animals were inseminated after ovulation, the spermatozoa ascended the oviduct faster than when animals were inseminated before ovulation, and fertilization commenced in 4 hr. Regardless of the time of insemination, the spermatozoa participating in fertilization appeared to undergo the acrosome reaction after they reached the proximal part of the oviduct or when they were very near the eggs.
TL;DR: The similarity in observed and expected distributions indicated that a functional zona reaction was absent in eggs inseminated in vitro, and sperm penetration of zonae and fertilization of mouse eggs in vitro as a function of sperm concentration over the range 10(3)-10(6) cells/ml.
Abstract: Sperm penetration of zonae and fertilization of mouse eggs in vitro was studied as a function of sperm concentration over the range 10(3)-10(6) cells/ml. Maximal fertilization was obtained at 10(5) sperm/ml with markedly reduced levels seen at lower concentrations. Eggs inseminated at low sperm concentrations were, however, characterized by the absence of multiple sperm penetrations of their zonae and by the retention of an intact cumulus oophorus during culture. Penetration levels were similar in eggs inseminated with and without an intact cumulus, although increases in supernumerary and supplemental sperm were observed with partly denuded ova. The distribution of sperm found within eggs inseminated in vitro was compared with a distribution predicted by chance alone. The similarity in observed and expected distributions indicated that a functional zona reaction was absent in eggs inseminated in vitro. Sperm binding to zonae of cumulus-free unfertilized mouse eggs was shown to be related to sperm concentration over the range 10(3)-10(6) cells/ml. Zonae sperm binding sites, while too numerous for accurate quantitation, exceeded 100 per zona. The interrelationships between sperm penetration of and sperm binding to the zonae of cumulus-free eggs were examined. At low sperm concentrations, the ratio of sperm/zonae with bound sperm to sperm/penetrated egg approached one, although the total number of bound sperm exceeded the total number of penetrating sperm. That proportion of cells in a preincubated epididymal sperm suspension, capable of binding to the zona was determined and employed in an estimation of the extent of sperm capacitation.
TL;DR: It does not seem that there is any species-specificity among three sea-urchins and one starfish used, and the role of the diffusate is discussed in relation to the penetration of spermatozoa through the jelly coat to the egg surface.
Abstract: Effects of pH and egg water on the respiration of sea-urchin spermatozoa were polarographically studied in three sea-urchins and one starfish species. Sea-urchin sperm respiration is extremely sensitive to change in the pH of the suspending medium over a wide range. In normal-sea water, the pH of the sperm suspension decreased from 8.02 to 7.62, after four to five minutes' incubation at 18 degrees C. The Respiratory Dilution Effect could be recognized in the same medium. However, when sea water was buffered with HEPES at pH 8.2, the Effect was no longer observed. The diffusate from egg water (jelly coat solution) brought about a striking increase in the respiration when added to moderately respiring spermatozoa in HEPES-sea water of pH values lower than 7.9. No inccrease in the respiration was observed when the diffusate was added to vigorously respiring spermatozoa in HEPES-sea water of pH values higher than 8.2. Sperm motility was also inhibited by acid pH, and this inhibition was reversed by the addition of the diffusate. It does not seem that there is any species-specificity among three sea-urchins and one starfish used. The role of the diffusate is discussed in relation to the penetration of spermatozoa through the jelly coat to the egg surface.
Journal Article•
TL;DR: Results provide evidence for the lack of immunologic tolerance in man toward many sperm antigens, and antibodies to acrosomal antigen Acl and equatorial antigen, which occurred most frequently, appeared to crossreact with ubiquitous microorganisms.
Abstract: Naturally occurring human antisperm antibodies (ASA) detectable by immunofluorescence, were found to have a peak indicence of 90% in both sexes before puberty. Thereafter, the incidence declined to about 60% and persisted through life. This age-related incidence resembled that for foreign and not self antigens. The natural incidence of the six antibodies under investigation varied: the most frequent were antibodies to acrosomal antigen Acl and equatorial antigen; the least frequent were antibodies to acrosomal antigen Ac2 and sperm nuclear protamine; and between these were antibodies to the mainpiece of tail and post-acrosomal region. Irrespective of their natural incidence, these antibodies increased at a comparable rate in men following vasectomy indicating these six sperm antigens have comparable immunogenicity. These results provide evidence for the lack of immunologic tolerance in man toward many sperm antigens. The variation in the natural incidence of individual ASA is explanable by differences in prevalence of crossreaction between each sperm antigen with exogenous antigens. Thus, antibodies to acrosomal antigen Acl and equatorial antigen, which occurred most frequently, appeared to crossreact with ubiquitous microorganisms.
TL;DR: Spin label probes were used in conjunction with measurements of metabolic rate and electron microscopy to characterize bovine sperm membranes to quantify changes in sperm membranes occurring during the epididymal maturation of sperm and subsequent events within the female tract leading to fertilization.
Abstract: Spin label probes were used in conjunction with measurements of metabolic rate and electron microscopy to characterize bovine sperm membranes. Aqueous compartments, membrane hydrocarbon zones and lipid : water interfaces were studied separately using appropriate spin labels. For sperm suspended in aqueous medium, the cold shock associated with rapid cooling from room temperature to 0/sup 0/ increased membrane permeability. This membrane damage was readily detected using spin labels but was not detected using thin section electron microscopy. This change was prevented by the addition of butylated hydroxy toluene (BHT). BHT provided partial protection against further damage caused by freezing sperm on solid CO/sub 2/. ESR techniques provide a rapid means to quantify the changes in sperm membranes occurring during the epididymal maturation of sperm and subsequent events within the female tract leading to fertilization. The technique also could be used to assess damage to sperm, ova or embryos during preparation for storage in cryoprotective diluents.