The influence of anti-zona and anti-sperm antibodies on sperm--egg interactions

Anti-zona antibodies are effective inhibitors of fertilization in vitro and, regardless of whether passive or active immunization techniques are used, in vivo. Antibodies raised against unfractionated zona pellucida antigens are chiefly directed against a group of carbohydrate-rich components localized on the outer surface of the zona. The interaction of anti-zona antibodies with these sites induces the formation of a surface precipitate which occludes the sperm binding sites by a process of steric hindrance, and stabilizes the zona structure against digestion by the proteolytic enzymes of the sperm head. Active immunization studies indicate that the long-term induction of infertility without adverse side effects is feasible in both laboratory rodents and primates when the zona pellucida is used as a target. Anti-sperm antibodies also exhibit a capacity for inhibiting fertilization in vivo and in vitro. To determine the most appropriate detection method to screen patients for anti-sperm antibodies several homologous and heterologous antisera were analysed by 5 different agglutination and immobilization techniques and then compared for their ability to inhibit the fertilizing capacity of human spermatozoa using the zona-free hamster egg penetration test. The results obtained with the Franklin--Dukes tube--slide test exhibited the closest correlation with the anti-fertility activity of a given antiserum; this activity could be amplified by the addition of complement to the medium. It is concluded that antibodies directed against the sperm head are responsible for limiting the fertilizing capacity of human spermatozoa in vitro and that it is these antibodies of which attention should be focused to unravel the role that immunological factors play in the aetiology of infertility in vivo.

Antisperm antibodies: their effect on the process of fertilization studied in vitro

The influence of antisperm antibodies on the fertilizing capacity of human sperm was investigated in a zone-free hamster egg system using heterologous and homologous antisera. The ability of these antisera to interfere with the fertilizing capacity of human spermatozoa correlated well with the antibody titers obtained using the Franklin-Dukes tube slide test. However, there was little correlation between the antifertility effects of these antisera and their activities in the gelatin and tray agglutination tests. The addition of complement to the incubation medium amplified the inhibitory activity exhibited by these antisera, although the extent of this inhibitory influence bore no relationship to the antibody titers obtained using the complement-dependent sperm-immobilization technique. The study demonstrates the importance of the hamster egg penetration test in evaluating the antifertility effect of antisperm antibodies.

Active immunization of rats with cumulus-free mouse ova: induction of infertility and antibody titers

Active immunization of rats with cross-reacting zona pellucida antigens derived from cumulus-free mouse ova resulted in the induction in fertility without adverse side effects. Half of the immunized animals never regained their fertility despite repeated matings with fertile males. Two of the remaining animals conceived when antibody titers fell to basal levels and gave birth to litters of normal healthy young. Post mortem examination of immunized animals 24 hours after finding sperm in the vaginal smears resulted in the recovery of tubal ova exhibiting the presence of a precipitate on the outer surface of the zona pellucida. Some of these ova appeared to have been fertilized, suggesting that anti-zona antibodies may also inhibit fertility through a post-fertilization mechanism of action.

Failure to detect altered rosette inhibition titres in human pregnancy serum

Six anti-lymphocyte antisera and 6 anti-lymphocyte globulin preparations were tested on serum from women in the first and second trimester of pregnancy and on appropriate sera from non-pregnant controls. There were no differences and the results do not confirm the claim that the serum of pregnant women contains a factor that will prevent human lymphocytes forming spontaneous rosettes with sheep red blood cells, and that this serum factor makes its appearance early in pregnancy.

Protein patterns of human uterine flushings collected at various stages of the menstrual cycle

Uterine flushings and plasma collected from normal, parous women at various stages of the menstrual cycle were subjected to gel electrophoresis. The protein profiles of the flushings differed in many instances from the plasma pattern by the presence of between one and eleven non-plasma proteins. The distribution of the major non-plasma proteins during the menstrual cycle was not statistically significant but that of a pretransferrin, observed in uterine flushings and in peritoneal fluid, was significant. However, the appearance of this protein band could not be related to a particular phase of the cycle, and hence to a specific hormonal condition.

Effect of human uterine flushings collected at various stages of the menstrual cycle on mouse blastocysts in vitro

Mouse blastocysts were cultured in vitro in a defined medium supplemented with uterine flushings (containing 500 microgram protein/ml) obtained from normal women at various stages of the menstrual cycle. With one exception (uterine flushing collected on the last day of a menstrual period) blastocyst hatching and attachment were not impaired by flushings collected before or after ovulation.

Cyclic variation in concentrations of protein and hexose in human uterine flushings collected by an improved technique

Uterine flushings were obtained from fertile women at various stages of the menstrual cycle. A technique was used which excluded contamination with cervical mucus and significantly lowered contamination with blood in comparison with an established technique. Contamination of the uterine flushings with seminal plasma and tubal fluid was also prevented. The concentrations of protein and hexose in the uterine flushings, corrected for contamination with plasma, were significantly lower in the secretory stages than in the proliferative stages of the cycle. It is concluded that proteins and carbohydrates are present within the uterine lumen not only after ovulation but also during the preovulatory period.

The culture of mouse blastocysts in the presence of uterine flushings collected during normal pregnancy, delayed implantation and pro-oestrus

When day-3 mouse embryos were cultured in a simple medium supplemented with uterine fluids of mice autopsied on day 4 of pregnancy, 48 h after administration of oestradiol, or during pro-oestrus, the percentage of blastocysts hatching from the zona pellucida was significantly greater than in unsupplemented medium. In the presence of uterine fluids recovered during delayed implantation this stimulation of blastocyst hatching was not observed. When the culture medium was supplemented with dialysed uterine flushings containing 20 or 30 microgram protein/ml, both 'day 4' and 'delay' uterine proteins were equally effective in enhancing hatching frequency (P less than 0.05). The results suggested that 'delay' uterine fluids may contain a dialysable inhibitor of blastocyst activity. The putative inhibitor was not effective in the presence of serum, since uterine fluids recovered both on day 4 of pregnancy and during delayed implantation significantly increased the size attained by blastocyst outgrowths in the presence of foetal calf serum (P less than 0.01). The percentage of blastocysts exhibitng giant cell transformation and outgrowth was also increased (P less than 0.02) by these uterine fluids when the concentration of FCS in the medium was minimal (0.25%).

Changes in the protein content of mouse uterine flushings during normal pregnancy and delayed implantation, and after ovariectomy and oestradiol administration

The protein content of the mouse uterine lumen increased significantly (P less than 0-001) on Day 4 of pregnancy, the day of implantation. This increase was associated with the presence of 14 serum and 22 non-serum proteins in the lumen; the major serum proteins were classed as high molecular weight slow alpha-globulins, while the dominant non-serum components consisted of slow and fast alpha-globulins, 6 prealbumins and a large quantity of proteinaceous material migrating near the origin of the gels. During experimental and lactational delayed implantation the protein levels were constantly low, transferrin, haemoglobin and albumin dominating the protein pattern. After administration of oestradiol-17beta, however, a biphasic uterine response was detected, significant increases in luminal protein concentration being observed within 12 h and again at 40-48 h after injection. The first phase of this response involved an influx of serum and non-serum proteins into the uterine lumen, most proteins migrating as high molecular weight slow alpha-globulins. The second phase involved an increase in the intensity of many non-serum components, the major proteins having Ra values of 0-06, 0-10 and 0-32. The qualitative, but not the quantitative, aspects of this response to oestradiol were identical in the absence of blastocysts.

Ultrastructure of the blastocyst and endometrium of the roe deer (Capreolus capreolus) during delayed implantation

Transmission electron microscopy of the trophoblast cells during diapause revealed an abundance of electron-dense, membrane-bound granular inclusions and a marked lack of cytoplasmic organelles. The cells also possessed a well-developed covering of branched microvilli, numerous caveolae, micropinocytotic vesicles and a lamina of fine fibrillae. The progressive enlargement of the blastocyst during diapause was correlated with a decline in the height of the trophoblast cells and a reduction in the density of microvilli and caveolae associated with the outer membrane. The granular inclusions also declined in number and electron density during the delay phase, suggesting the progressive utilisation of energy reserves. Embryonic elongation was associated with the disappearance of the granular inclusions, a reduction in the amount of fibrillar material and a dramatic increase in the development of cytoplasmic organelles. During diapause, clear vesicles, apparently derived from the Golgi apparatus, gradually accumulated in the supranuclear region of each gland and non-ciliated duct cell. Embryonic elongation was associated with the sudden release of these vesicles into the glandular lumen and thence into the uterine lumen. Numerous apical protrusions were also observed projecting from the luminal and ductal epithelia at this time, suggesting the formation of an apocrine secretion. Another type of secretion was produced during the early stages of placental attachment by the hypertrophied granular endoplasmic reticulum of the ductal epithelium.