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At least 19 recordsLinked to original sources
PubMed1989

[Studies on the method of sterilization with ethylene oxide gas. 1. Sterilization procedure and sterilizing effect].

Undertaken to ensure perfection of sterilization with ethylene oxide gas (EO gas) in routine clinical laboratory practice, an investigation was made of the relationship between sterilization procedure and sterilizing effect using the film bag delivery system and chamber system. Using a biological indicator as a monitor of sterilizing effect, the efficiency of sterilization was studied under various likely conditions and compared. The results led to the following conclusions: 1. Sterilization with EO gas by the film bag delivery system, because of this procedure being unable to be performed at a constant temperature, was shown to prove inadequate due to insufficient exposure to gas especially in winter season (when room temperature fell below 10 degrees C). 2. With the EO gas sterilization method using the film bag delivery system, which is believed to be effective within the ordinary range of humidity of the atmosphere, sterilizing effect was recognized to be affected by excess wetting of an object of sterilization that was caused by inadvertent manipulation or due to a predisposing attribute of the object, such as shape or outline. 3. All materials are sterilized upon being packaged. It is necessary therefore to make best choice of package material with respect of texture and size. Reuse influence to sterilizing effect. 4. The method of sterilization with EO gas using the chamber system has the advantage in that operating conditions are all automatically controlled. For this reason, there was not a single instance of failure to sterilize due to inappropriateness of temperature and humidity. From these results it is concluded that sterilising effect was affected by sterilization procedure and condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Ethylene Oxide↗
PubMed2003

Sterilization failure, sterilization reversal, and pregnancy after sterilization reversal in Quebec.

OBJECTIVE: 1). To determine the likelihood of sterilization reversal and of subsequent sterilization after sterilization reversal among men and women and 2). to examine the likelihood of pregnancy after sterilization (contraceptive failure) and of pregnancy after sterilization reversal. METHODS: Payment data from the Quebec provincial health insurance system were obtained for each person undergoing vasectomy or female sterilization from January 1, 1980 to December 31, 1999 and linked through a unique identifying number for each person. Using standard techniques of survival analysis, we computed the cumulative probability of experiencing each of six events. RESULTS: Among women, 0.9% (of 311960) experienced a pregnancy after sterilization, 1.8% (of 321929) obtained a reversal after sterilization, 61% (of 4369) achieved a pregnancy after sterilization reversal and 48% achieved a delivery; 23% (of 4677) obtained a subsequent sterilization after reversal. Among men, 2.4% (of 310827) obtained a reversal after vasectomy and 18% (of 6694) obtained a subsequent vasectomy after reversal. All of these risks were much higher among those in the youngest age groups. CONCLUSION: Sterilization reversal and pregnancy after sterilization are not rare. Relatively high rates of reversal among the youngest age groups suggest a need for better counseling about alternative contraceptive strategies.

Adolescent↗
PubMed1997

Tubal sterilization and long-term risk of hysterectomy: findings from the United States collaborative review of sterilization. The U.S. Collaborative Review of Sterilization Working Group.

OBJECTIVE: To estimate the long-term probability of hysterectomy after sterilization according to demographic and clinical characteristics before the procedure. METHODS: We used a prospective, multi-center cohort study of 10,698 women undergoing tubal sterilization to examine the cumulative probability of hysterectomy up to 14 years after sterilization. Independent risk factors for subsequent hysterectomy were examined using the life-table approach and the Cox proportional hazards model. RESULTS: The cumulative probability of undergoing hysterectomy 14 years after sterilization was 17%. The highest long-term cumulative probabilities of hysterectomy occurred among women who, at the time of sterilization, reported a history of endometriosis (35%) or were older than 30 years and reported prolonged bleeding during menses (46%). Multivariate modeling demonstrated an independently increased risk of hysterectomy among women who, at the time of tubal sterilization, reported a history of heavy menstrual flow (relative risk [RR] 1.4; 95% confidence interval [CI] 1.1, 1.7), severe menstrual pain (RR 1.3; 95% CI 1.1, 1.6), bleeding of more than 7 days during menstrual cycles (RR 1.8; 95% CI 1.1, 2.8), pelvic inflammatory disease (RR 1.3; 95% CI 1.04, 1.7), ovarian cysts (RR 1.6; 95% CI 1.2, 2.0), endometriosis (RR 2.5; 95% CI 1.7, 3.9), or uterine leiomyomata (RR 2.7; 95% CI 2.0, 3.7). CONCLUSIONS: Although women with gynecologic disorders before tubal sterilization were at greater risk of hysterectomy during the 14 years after sterilization than were women without these disorders, the majority of sterilized women in both categories did not undergo subsequent hysterectomy.

Adolescent↗
PubMed1998

Higher hysterectomy risk for sterilized than nonsterilized women: findings from the U.S. Collaborative Review of Sterilization. The U.S. Collaborative Review of Sterilization Working Group.

OBJECTIVE: To compare the risk of hysterectomy among previously sterilized women and women whose husbands had undergone vasectomy, and to evaluate whether this risk differed by age at surgical procedure or by method of tubal occlusion. METHODS: Our study population comprised 7718 women enrolled in a prospective, multicenter cohort study between 1978 and 1986. After stratifying by the woman's age at surgical procedure, we used the life-table approach and adjusted hazards ratios to examine whether the relative risk of hysterectomy during the 5 years after enrollment differed between the 7174 women who had been sterilized and the 544 women whose husbands had undergone vasectomy. RESULTS: The 5-year cumulative probability of hysterectomy was 8% among the previously sterilized women and 2% among the women whose husbands had undergone vasectomy. Among women 34 years of age and younger at enrollment, sterilized women were 4.4 times as likely to have a hysterectomy as women whose husbands had undergone vasectomy (95% confidence interval [CI] 1.9, 10.0). Findings were similar for women 35 years of age and older (rate ratio = 4.6; 95% CI 1.4, 14.5). Each of the six most commonly used methods of tubal occlusion was associated with an increased risk of hysterectomy. CONCLUSION: Women undergoing tubal sterilization were more likely than women whose husbands underwent vasectomy to undergo hysterectomy within 5 years after sterilization, regardless of age at sterilization. An increased risk of hysterectomy was observed for each method of tubal occlusion.

Adult↗
PubMed1987

Sterilization. Steam sterilizers and steam sterilizer standards--Australia.

The objectives that I have adopted for my contribution are: To describe the "environment" surrounding steam sterilization in Australian Hospitals; To describe the origin and features of current Australian steam sterilizer Standards; and To discuss some directions for future changes to hospital steam sterilization in Australia.

Australia↗
PubMed1998

Costs of low-temperature plasma sterilization compared with other sterilization methods.

Plasma sterilization is a new technique for decontaminating thermolabile products without the severe drawbacks associated with gas sterilization methods (residues, environment compatibility). The actual costs, per sterilization unit, of three sterilization techniques--plasma, ethylene oxide and formaldehyde--were compared. As plasma sterilization is an alternative to steam sterilization for sterilizing thermostable but easily corroding products or electronic instruments, costs for steam sterilization were calculated and compared as well. If one considers only the cost of the sterilization procedure itself, without taking into account the time-saving element of plasma sterilization, then ethylene oxide sterilization proves to be the most expensive procedure, followed by plasma sterilization; sterilization with formaldehyde was the least expensive. Inclusion of the time required to sterilize an instruments, however, altered the relative costs of the three methods. Because plasma sterilization takes less time to perform than either ethylene oxide or formaldehyde sterilization, fewer instruments need be procured. In order to measure and compare the time-saving advantage that plasma sterilization affords, five groups of instruments were assembled and the total cost of sterilizing an instrument of each group was calculated. The five groups included (1) disposable, (2) electronic, (3) endoscopic, (4) sharp and (5) standard instruments. In all cases, ethylene oxide sterilization was the most expensive method. Formaldehyde sterilization was, in four out of five cases, more expensive than plasma sterilization. Steam sterilization proved to be the cheapest method of sterilizing a laparoscopic set, even when costs due to damage inflicted on the optical instruments were calculated. In the case of a vitrectome, however, plasma sterilization costs were nearly the same as steam sterilization when the lower rate of damage by plasma sterilization was taken into account.

Costs and Cost Analysis↗
PubMed1996

Comparison of ion plasma, vaporized hydrogen peroxide, and 100% ethylene oxide sterilizers to the 12/88 ethylene oxide gas sterilizer.

OBJECTIVE: The performance of a standard gas sterilizer, which uses a mixture of 12% ethylene oxide (EtO) and 88% chlorofluorocarbon as the sterilizing gas (12/88), was compared to selected gas, ion plasma, and vaporized hydrogen peroxide (H2O2) sterilizers that do not use chlorofluorocarbons. The effect of serum and salt on sterilizer performance was evaluated. DESIGN: Test carriers (porcelain and stainless steel penicylinders, or 125-cm lengths of plastic tubing [internal diameter of 3.2 mm]) were inoculated with Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa, Mycobacterium chelonei, Bacillus stearothermophilus spores, Bacillus subtilis spores, and Bacillus circulans spores and then subjected to sterilization using 12/88, 100% EtO, ion plasma, or vaporized H2O2. The bacterial inoculum was prepared with and without 10% serum and 0.65% salt, and the residual bacterial load after sterilization as determined using viable counts. RESULTS: All of the sterilizers tested effected a six-log10 reduction of the bacterial inoculum on penicylinders, unless 10% serum and 0.65% salt were present, in which case the 100% EtO, vaporized H2O2, and ion plasma sterilizers were not as effective as the 12/88 sterilizer. None of the sterilizers could eradicate 10(6) CFU of all of the bacteria in 10% serum and 0.65% salt when inoculated inside a narrow lumen. CONCLUSIONS: The margin of safety for the 100% EtO, vaporized H2O2, and ion plasma sterilizers is less than that of the 12/88 sterilizer. The inability of all sterilizers, including the 12/88, to kill organisms in narrow lumens reliably when serum and salt were present raises concern about the current practice of gas sterilization of flexible endoscopes.

Analysis of Variance↗
PubMed1998

Comparison of liquid chemical sterilization with peracetic acid and ethylene oxide sterilization for long narrow lumens.

The aim of this study was to determine how well peracetic acid liquid chemical sterilization (LCPAS) killed test organisms in the presence of 10% fetal bovine serum and 0.65% salt challenge (RPMI-S) compared with a 100% ethylene oxide (ETO) sterilizer and an ETO hydrochlorofluorocarbon (ETO-HCFC) sterilization method with long (125 cm), narrow (3-mm internal diameter) flexible lumens as the test carrier. The inoculated lumens were dried overnight before processing. The test organisms included Mycobacterium chelonei, Enterococcus faecalis, and Bacillus subtilis. For all 3 organisms tested, the LCPAS process resulted in a 6 log10 reduction in bacterial load compared with a 2.5 log10 to 6 log10 reduction for the 100% ETO and ETO-HCFC sterilizers. Sterilization was achieved for 100%, 61%, and 67% of the lumen test carriers for the LCPAS, 100% ETO, and ETO-HCFC sterilizers, respectively. The data indicate that of the sterilization methods evaluated, LCPAS was the most effective for sterilizing narrow flexible lumens in the presence of residual inorganic and organic soil. This effectiveness was achieved through a combination of organism wash-off and peracetic acid sterilant killing of organisms. Salt was the major compounding factor for effective ETO gas sterilization, because carriers inoculated with organisms in 10% fetal bovine serum alone all were sterilized by both 100% ETO and ETO-HCFC sterilization methods. Our data support the critical need to ensure adequate precleaning of narrow flexible lumen endoscopes before any sterilization method.

Bacillus subtilis↗
PubMedDate not supplied

Genetics and cytology of a genic male-sterile, female-sterile mutant from a transposon-containing soybean population.

A male-sterile, female-sterile soybean mutant (w4-m sterile) was identified among progeny of germinal revertants of a gene-tagging study. Our objectives were to determine the genetics (inheritance, allelism, and linkage) and the cytology (microsporogenesis and microgametogenesis) of the w4-m sterile. The mutant was inherited as a single recessive nuclear gene and was nonallelic to known male-sterile, female-sterile mutants st2 st2, st3 st3, st4 st4, st5 st5, and st6 st6 st7 st7. No linkage was detected between the w4-m sterile and the w4w4, y10 y10, y11 y11, y20 y20, fr1 fr1, and fr2 fr2 mutants. Homologous chromosome pairing was complete in fertile plants. Chromosome pairing, as observed in squash preparation, was almost completely absent in sterile plants. Developmentally microsporogenesis proceeded normally in both the fertile and the w4-m sterile through the early microspore stage. Then the tapetal cells of the w4-m sterile surrounding the young microspores developed different-size vacuoles. These tapetal cells became smaller in size and separated from each other. Some of the microspores of the w4-m sterile also became more vacuolate prematurely and sometimes they collapsed, usually by the late microspore stage. In the w4-m sterile the microspore walls remained thinner and structurally different from the microspore walls of fertile plants. No pollen was formed in the mutant plants, even though some of the male cells reached the pollen stage, although without normal filling. The w4-m sterile was designated st8st8 and assigned Soybean Genetic Type Collection number T352.

Chlorophyll↗
PubMed1997

The risk of ectopic pregnancy after tubal sterilization. U.S. Collaborative Review of Sterilization Working Group.

BACKGROUND: Tubal sterilization is an increasingly common method of contraception in the United States. Although pregnancy after sterilization is uncommon, it can occur and may be ectopic. We used data from the U.S. Collaborative Review of Sterilization to estimate the risk of ectopic pregnancy in women who had undergone the common types of tubal sterilization. METHODS: A total of 10,685 women undergoing tubal sterilization were followed in a multicenter, prospective cohort study. We intended to follow all the women for 5 years by means of annual telephone interviews; for women enrolled early in the study, we attempted an additional follow-up telephone interview 8 to 14 years after sterilization. To assess the risk of ectopic pregnancy in these women, we used cumulative life-table probabilities and proportional-hazards analysis. RESULTS: There were 47 ectopic pregnancies in the 10,685 women; the 10-year cumulative probability of ectopic pregnancy for all methods of tubal sterilization combined was 7.3 per 1000 procedures. The cumulative probability varied substantially according to the method of sterilization and the woman's age at the time of sterilization. Women sterilized by bipolar tubal coagulation before the age of 30 years had a probability of ectopic pregnancy that was 27 times as high as that among women of similar age who underwent postpartum partial salpingectomy (31.9 vs. 1.2 ectopic pregnancies per 1000 procedures). The annual rate of ectopic pregnancy for all methods combined in the 4th through 10th years after sterilization was no lower than that in the first 3 years. CONCLUSIONS: A history of tubal sterilization does not rule out the possibility of ectopic pregnancy, even many years after the procedure.

Adolescent↗
PubMed1999

Biological monitoring of sterilizers and sterilization failures in Norwegian dental offices in 1985 and 1996.

It is essential that dental office sterilizers be regularly challenged with biological indicators (BIs) in order to prove that the test spores are being killed during sterilization. The aims of the study were to biologically monitor Norwegian dental office sterilizers and to identify factors contributing to sterilization failure. In 1985, participants received a packet containing: (i) 4 BI units; (ii) a set of instructions; (iii) a questionnaire concerning operation (including biological monitoring) of the office sterilizer(s), and (iv) a return-address envelope. In 1996, offices were sent (i) a survey which included demographic questions and inquiries concerning instrument sterilization processes; (ii) 2 sets of 3 BI units with instructions for their use on 2 different days; (iii) 1 control BI unit that was not to be processed, and (iv) a return-address envelope. Both private and public offices participated. Response rate to the 1996 study was 60%, which was 9.1% of all dental offices in Norway. Testing results indicated a 6.3% overall sterilization failure rate. Three out of 163 steam autoclaves (SAs) (1.8% of total) and 14 out of 109 dry heat (DH) ovens (12.8% of total) failed. DH ovens were over 7 times more likely to fail BI testing than were SAs (chi2, P < 0.01). Demographic or hygiene procedural factors could not be correlated to sterilization performance (chi2, P > 0.05). The failure rate for SAs (n = 216) in 1985 was almost 5 times greater than in 1996 (8.8% vs 1.8%). Improvement in sterilizer performance during the decade may be related to issuance in 1986 of Norway's 1st infection control guidelines for dentistry and greater awareness of infection control practices and/or to increases over the previous 10 years in the number of postgraduate courses offered in infection control. The current Norwegian guidelines on infection control practices in public health services, including dentistry, recommend regular biological monitoring of sterilizers without specifying how often. There is a lack of information among Norwegian dentists as to how frequently dental office sterilizers should be regularly monitored by BI.

Chi-Square Distribution↗
PubMed1984

Tubal sterilization. A prospective long term investigation of 218 sterilized women.

The present study is a long-term investigation of 218 consecutively sterilized women in Akershus County, Norway. The operations were performed in 1973-74, when the access to sterilization was regulated by a legislation from 1934. The women were interviewed personally, and a clinical examination was performed before sterilization, at discharge from hospital, three months, one and six years later. At each occasion the participation was about 95%, and only one woman was lost to follow-up. The women in this series lived in stable social conditions, their average age was 33.7, their parity 2.8. They were not socially distinguishable from women of the same age in the county at large, but there were important socially and age related differences within the series. Their contraceptive usage was widespread, but inconsistent. Family planning was the all-dominant motive. Forty per cent of the women had been suggested the sterilization by a doctor, 30% at abortion application. The operations were performed as laparoscopic electrocoagulation of the tubes or as a Pomeroy resection. Five pregnancies were recognized in the study period, four of these in the laparoscopy group. There were few serious complications, but 20% had a diversity of complaints at the three month interview. At six years seven women had complaints attributed to the operation. The large majority of the series was satisfied with the sterilization. Almost half the women would have preferred an even earlier operation, and six years after the sterilization 85% of the women had told friends about it, and 71% of these had directly recommended sterilization to someone. Six years after the sterilization 74% said the operation should be more widespread, 69% believed postoperative regret was uncommon, and the impact on postoperative marital life was mainly positive. However, during the study period, 18% of the women had experienced regret, ambivalence or periodic depression because of their sterilization. The rate of, and reasons for regret varied with time. The rate increased; at six years 6% of the women would have preferred the sterilization undone, and in 10% of the couples at least one of the partners held that view. At one year, the primary reason for regret was a feeling of having been persuaded by the doctor at abortion application. Six years after the sterilization the desire for a child with a new spouse was the principle reason. There was no association between regret and age or parity at operation.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1999

A review: taking the sterile out of sterility.

Users of in-dwelling medical devices, prostheses and surgical dressings rely implicitly on their sterility. Rarely do consumers give any thought to what sterility really means. The general assumption is that manufacturers have adopted the most efficient and cost-effective methods of achieving sterility. Currently, terminal sterilization processes appropriate for the manufacture of medical devices are those that are deemed to give less than one chance in a million of a single, finished product item containing a viable organism. Such a definition of sterility is embodied in the European standard EN556 as a Sterility Assurance Level of 10(-6), based on the properties of heat-resistant endospores. However, is this level of sterility assurance appropriate for all categories of medical device? Moreover, do all medical devices which are labelled as sterile require the same level of treatment? This paper will demonstrate that in some instances, the high standards set for sterilization processing are unreasonable, not cost-effective and exclude new sterilization technologies from being accepted by the regulatory authorities.

Equipment and Supplies↗
PubMed1984

The rationale and a computer evaluation of a gamma irradiation sterilization dose determination method for medical devices using a substerilization incremental dose sterility test protocol.

The experimental procedure described is designed to allow calculation of the radiation sterilization dose for medical devices to any desired standard of sterility assurance. The procedure makes use of the results of a series of sterility tests on device samples exposed to doses of radiation from 0.2 to 1.8 Mrad in 0.2 Mrad increments. From the sterility test data a 10(-2) sterility level dose is determined. A formula is described that allows a value called DS Mrad to be calculated. This is an estimate of the effective radiation resistance of the heterogeneous microbial population remaining in the tail portion of the inactivation curve at the 10(-2) dose and above. DS Mrad is used as a D10 value and is applied, in conjunction with the 10(-2) sterility level dose, to an extrapolation factor to estimate a sufficient radiation sterilization dose. A computer simulation of the substerilization process has been carried out. This has allowed an extensive evaluation of the procedure, and the sterilization dose obtained from calculation to be compared with the actual dose required. Good agreement was obtained with most microbial populations examined, but examples of both overdosing and underdosing were found with microbial populations containing a proportion of organisms displaying pronounced shoulder inactivation kinetics. The method allows the radiation sterilization dose to be derived from the natural resistance of the microbial population to gamma sterilization.

Computers↗
PubMed1983

[Dependency of a microbiological test of a formaldehyde gas sterilization procedure on the shape of objects to be sterilized].

During the last decade, a number of procedures have been developed by different firms for the sterilization of heat-sensitive instruments using a mixture of formaldehyde and water vapor at a temperature of approximately 60 degrees C as means of sterilization. Instruments to be sterilized by this technique as e.g. sounds and catheters normally have long narrow cavities. Therefore, the formaldehyde gas sterilization procedures have to be tested primarily for their capability of achieving a sufficient microbicidal effect within those cavities. For this purpose, the bioindicators are placed into special test pieces. The test pieces commonly in use differ widely in their construction, shape, and size. They mostly consist of some hollow cylinder with an attached capillary or a tube (see Table 1). The authors demonstrated by means of models that the variety of test pieces in use meant that the sterilization procedures had to meet quite different requirements. The models consisted of flexible tubes differing in diameter and length and were connected to short glass tubes. These glass tubes having identical or wider inner diameters than the flexible tubes served as receptacles containing the bioindicators. Spores of Bacillus stearothermophilus served as test organisms. The spores were suspended in defibrinated sheep blood and dried on filter paper. The efficiency of the sterilization technique was measured in terms of the relative number of indicator strips with surviving germs (i.e. non-sterilized indicators) after treatment of the test pieces with the formaldehyde gas. At first, the test results were examined as to their dependency on the length of the flexible tubes. These tubes were 3 mm wide and 5 to 100 cm long, each being sealed at one end and with the bioindicators placed near the sealed end. The percentage of indicators with surviving germs increased with the length of the tubes. After the sterilization process, nearly all indicators (92%) contained in the 1 m tubes proved to be non-sterile (see Table 2). The same results were obtained with tubes open at both ends, with the bioindicators located in the middle section of the tubes (see Table 3). Using tubes of 1 m length, the dependency of the test results on the inner diameter of the test pieces was demonstrated. While all indicators placed into tubes of 3 mm inner diameter still contained surviving germs, those in the tubes of 9 mm inner diameter were all sterile (see Table 4).(ABSTRACT TRUNCATED AT 400 WORDS)

Bacteriological Techniques↗
PubMed1993

The efficacy of low temperature plasma (LTP) sterilization, a new sterilization technique.

The efficacy of low temperature plasma (LTP) sterilization, a newly developed sterilization procedure was tested. Following experiments were carried out: Determination of the most resistant test organism, influence of 10% and 20% defibrinated sheep blood or varying salt concentrations on the efficacy of the sterilization process, influence of the carrier position in the sterilization chamber and in the sterilization pouches, influence of a loaded sterilization chamber, comparative efficacy of EO and LTP, steel carriers with a blood burden of 0%, 5% and 10%, comparative efficacy of EO and LTP, strip carriers in endoscopes, blood burden 0% and 10%, with and without adaptors, evaluation of two bioindicator models. B. pumilus was the test spore that overall seemed to be most resistant to the sterilization procedure. Supplementation of the test suspension with blood or saline crystals resulted in significantly reduced efficacy and has to be avoided in practical operation. The fully loaded sterilization chamber or the position of germ carriers on the shelves had no negative influence on the effectivity of the sterilization process. There were no significant differences between EO and LTP, the blood burden not exceeding 5%. 10% blood burden resulted in a significantly weaker action of LTP. For sterilization of long lumens adaptors containing hydrogen peroxide are necessary. An appropriate bioindicator tube model is introduced.

Aspergillus niger↗
PubMed2002

Re-examination of sibling cross-sterility in the ascidian, Ciona intestinalis: genetic background of the self-sterility.

Self-sterility of solitary ascidians is a typical example of the allogeneic recognition, though its molecular mechanism remains an open question. In this paper we analyze the fertility between siblings from selfed and crossed eggs to understand the genetic basis of self-sterility in the ascidian, Ciona intestinalis. First, we show that the self-sterility is strict and stable, and the individuality expressed in gametes is highly diversified in the wild population that we used. Secondly, we show one-way cross-sterility and reciprocal cross-sterility within the siblings that are self-sterile but fertile with non-siblings. Thirdly, we show self-sterility and cross-sterility share some natures and both are closely related to the sperm capacity not to bind to the vitelline coat of the autologous eggs or the eggs sterile to the sperm concerned. In all, this paper shows that the self-sterility is genetically governed by a multiple-locus system, and that most probably individual-specific determinants are haploid expression in sperm and diploid expression in eggs, given they recognize self but not non-self.

Acids↗