Assessment of the effect of testosterone on the acrosome reaction of human spermatozoa.

In the acrosome reaction, the spermatozoon plasma membrane fuses with the outer acrosomal membrane, resulting in the release of the acrosomal content. Several compounds, such as sex steroids, are known to modulate the acrosomal exocytosis. Testosterone regulates various functions in male reproductive physiology; however, little is known about the relationship between testosterone and the acrosome reaction. Thus, our objective was to study the effect of testosterone on the acrosome reaction of human spermatozoa. To evaluate the acrosomal exocytosis, spermatozoa were incubated with testosterone (0.2, 2.0 and 20 nmol l(-1)), progesterone and control medium for 60, 120, 240 and 1440 min. The acrosome reaction was assessed by staining with Hoechst 33258 and fluorescein isothiocyanate-conjugated P. sativum agglutinin lectin. In general, spermatozoa incubated with progesterone had the highest percentage of acrosomal exocytosis. The percentage of acrosome reaction obtained in the three treatments with testosterone differed from that observed for progesterone at 120, 240 and 1440 min (24 h). Additionally, significant differences were found between testosterone (2.0 and 20 nmol l(-1)) and progesterone after 60 min. Differences between control and the three testosterone treatments studied were obtained only at 1440 min. In general terms, these results show that testosterone exerts no inductor effects on the acrosome reaction of human spermatozoa.

Physiological action of oestradiol on the acrosome reaction in human spermatozoa.

The acrosome is a secretory vesicle located in the sperm head. The acrosome reaction consists in the fusion of the sperm plasma membrane with the external acrosomal membrane. It has been observed that this reaction does not take place in spermatozoa incubated in cervical mucus, hydrogel that contains high concentrations of oestradiol in the peri-ovulatory period. The objective of the present study was to analyse the influence of oestradiol on the acrosome reaction in human spermatozoa to evaluate the possible inhibitory effect of this hormone. Spermatozoa were incubated in progesterone (10.1 nmol l(-1)); oestradiol plus progesterone (oestradiol at 840 pmol l(-1) and progesterone at 10.1 nmol l(-1)), oestradiol (840 pmol l(-1)) and control (without steroidal hormones) for 30 min, 60 min, 240 min and 24 h. The acrosome reaction was evaluated by stain with Hoechst 33258 and fluorescein isothiocyanate-conjugated Pisum sativum agglutinin lectin. Progesterone-incubated spermatozoa showed the highest percentage of acrosome reaction (P < 0.05). Spermatozoa incubated with oestradiol and oestradiol plus progesterone showed the lowest percentage of acrosome reaction. The present study demonstrates the inhibitory role of oestradiol on the acrosome reaction, stimulated by progesterone in human spermatozoa under physiological conditions.

Tres versiones del "Ogtt Squeezer", un programa para evaluar de un vistazo la información metabólica de la curva de tolerancia a la glucosa / Three versions of the "Ogtt Squeezer", a program to evaluate ataglance the metabolic information of the oral glucose tolerance test

El diagnóstico clínico de resistencia insulínica (RI) es difícil, ya que el Clamp no es aplicable a la clínica. El así llamado "síndrome metabólico", un predictor clínico de la RI, no identifica alrededor de la mitad de los sujetos afectados. Previamente, definimos adecuadamente (Análisis ROC) los niveles de corte diagnóstico de los siguientes predictores bioquímicos: HOMA1, HOMA2, QUICKI e ISI-Composite, a través de analizar datos de 90 sujetos (53 no resistentes y 37 resistentes) que tenían una medición directa de su resistencia insulínica (Test de supresión pancreática, TSP, Test de Reaven) y también, una curva de tolerancia a la glucosa oral (CTG). Los puntos de corte obtenidos exhibieron un mucho mejor desempeño diagnóstico comparados con los puntos de corte convencionales. También encontramos un predictor nuevo, simple, económico y eficiente, el I0*G60. Definimos la "normalidad metabólica" de la CTG usando las medianas de los valores de varios parámetros en 312 sujetos con un G120 dentro de los 2 primeros terciles del grupo de normo-tolerantes a la glucosa (NGT, n=468; G120: 51-110 mg/dL, los con mejor función beta insular). A las medianas de la función beta insular y de la sensibilidad insulínica se les asignó un valor de un 100%. Se calculó el % relativo de función beta insular (%RFBI) y el % relativo de sensibilidad insulínica (%RSI) del resto de la cohorte (n=573) contra estos valores de referencia. El "OGTT Squeezer" se escribió en Excel. Las glicemias y las insulinemias de la CTG fueron las entradas del programa. Las salidas fueron: I0*G60, ISI-OL, QUICKI, and HOMA1 (predictores) y el índice insulinogénico, el índice de disposición, %RFBI y %RSI (parámetros). El programa también caracterizó la tolerancia glucídica de acuerdo a los criterios de la ADA 2003. El formato final del programa, HTML 5, facilita su uso. Desarrollamos tres versiones del programa: completa, abreviada y mínima.

Clinically, diagnosing insulin resistance (IR) is difficult since the Clamp is not applicable to clinical work. The so-called "Metabolic Syndrome", a clinical surrogate of IR, fails to identify around 50% of affected subjects. Previously, we properly defined (ROC Analysis) the diagnostic cut-offs of the following biochemical predictors: HOMA1, HOMA2, QUICKI, and ISI-Composite by analyzing data from 90 subjects (53 non-insulin-resistant and 37 insulin-resistant subjects) who had a direct measurement of insulin resistance (Pancreatic Suppression Test, PST, Reaven's Test), and also, an Oral Glucose Tolerance Test (OGTT). The resulting cut-offs exhibited much better performances compared with the conventional cut-offs. We also found a new, simple, inexpensive and efficient predictor, the I0*G60. We chose to define the "metabolic normalcy" of the OGTT by using the median values of several parameters in 312 NGT subjects with a G120 in the first 2 tertiles of the NGT group (n=468; G120: 51-110 mg/dL, those with the best beta-cell function). The median values of both Beta-Cell Function and Insulin Sensitivity of these subjects were assigned a 100% value. Both % Relative Beta-Cell Function (%RBCF) and % Relative Insulin Sensitivity (%RIS) of everyone else in the cohort (n=573) was calculated against these reference values. The "OGTT Squeezer" was written in Excel. The OGTT's glucose and insulin values served as the inputs of the program. The outputs were: I0*G60, ISI-OL, QUICKI, and HOMA1 (predictors), and Insulinogenic Index, Disposition Index, %RBCF, and %RIS (parameters). Moreover, the program characterized the OGTT according to the ADA 2003 criteria. The HTML 5 format of the program facilitates its use. We developed 3 versions of the program: complete, abbreviated, and minimal versions.

Primary association of a TNF gene polymorphism with susceptibility to multiple sclerosis.

The associations of three promoter polymorphisms in the tumor necrosis factor (TNFA) gene have been studied in 238 patients and 324 control subjects. A significant correlation was found between MS susceptibility and the TNFA-376 polymorphism. This association was independent of the human leukocyte antigen (HLA) class II association and the combined inheritance of HLA-DRB1*1501 and the TNFA-376A allele more than additively increased susceptibility to MS.

Celiac disease and TNF promoter polymorphisms.

The possibility that genetic susceptibility to celiac disease (CD) might be influenced by tumor necrosis factor (TNF) genes polymorphism has repeatedly been put forward. To date, this has only been investigated in case-control studies and results have been contradictory. In order to avoid any possible ethnic mismatching between patients and controls, we have approached this problem studying 71 celiac families, establishing the parental haplotypes and comparing CD versus control haplotypes (the so-called AFBAC or affected family-based controls). We used DNA-based methods to screen for HLA-DRB1, -DQA1, and -DQB1 alleles, TNFalpha promoter polymorphims and TNFa and b microsatellites. The guanine-to-adenine polymorphism at position -308 of the TNFalpha gene promoter region was found associated with CD as the TNF-308A allele appeared significantly increased in frequency in CD haplotypes, and this was shown to be independent of the association between CD and the DRB1*0301,DQA1*0501,DQB1*0201 alleles. Our results indicate that at least another gene, in addition to the known association of CD with HLA class II, has a susceptibility role in this disease. This should be either TNFalpha or another polymorphic gene in the telomeric end of the HLA class III region.

Susceptibility to multiple sclerosis mediated by HLA-DRB1 is influenced by a second gene telomeric of the TNF cluster.

Susceptibility to multiple sclerosis (MS) is clearly associated with human leukocyte antigen (HLA)-DRB1*1501, but some studies show associations with HLA-B7 and -B18. These are often co-expressed with DRB1*1501 in the ancestral haplotypes (AH) denoted 7.1 (HLA-A3, B7, tumor necrosis factor [TNF]a11b4, DRB1*1501) and 18.1 (HLA-A25, B18, TNFa10b4, DRB 1*1501). Here we present a systematic study of 218 patients and 274 controls typed at all standard class II and TNF microsatellite loci, and a novel non-synonymous polymorphism in the central major histocompatibility complex gene, inhibitor of kappa B-like protein (IKBL). The C allele at IKBL+738 is only found on the 7.1 haplotype. HLA-DRB1*1501 was associated with disease, as expected. When subjects expressing DRB 1*501 were analyzed separately, TNFa11b4 and IKBL+738C were less common in the patients and, hence, mark an allele that mediates resistance which lies telomeric of IKBL. TNFa10b4 and TNFa1b5 were more common in DRB1*1501 patients than in controls. These alleles have been associated with the 18.1 and 18.2 AH, respectively. Since no component of these haplotypes was an independent risk factor in this study, it appears likely that a gene linked to TNFa10b4 and TNFa1b5 modifies the effect of the susceptibility locus marked by HLA-DRB1*1501. Potential candidate genes telomeric of the TNF cluster are discussed.

Pancolitis and genetic markers in the Spanish population.

BACKGROUND: although the etiology of ulcerative colitis disease remains an enigma, the importance of the major histocompatibility complex genes has been described, as in many other autoimmune diseases. AIM: we investigated the contribution of HLA-DRB1, DQA1 and DQB1 genes (HLA region) in patients with pancolitis. METHODS: we studied a total of 89 patients diagnosed as having ulcerative colitis (34 pancolitis and 55 left colitis) and 275 healthy control subjects. Complete information on sex, age, family history, age of onset, localization, complications, surgery and treatment was obtained from all patients. DNA was extracted from peripheral blood leukocytes and all individuals were HLA-DRB1 genotyped. RESULTS AND CONCLUSIONS: there was an association between pancolitis and the presence of DR4-Val86 (p = 0.009; OR = 3.3) and DRB1*0103 (p = 0.02; OR = 5.1) alleles. In patients with left colitis an association with DRB1*1501 (p = 0.03; OR = 1.9) and DRB1*0103 alleles (p = 0.03; OR = 3.8) was observed. We conclude that a strong association between DR4-Val86 and pancolitis exists.

[Unknown primary cancer: revision of our experience. Preliminary study]. / Cáncer de origen desconocido: revisión de nuestra experiencia. Estudio preliminar.

The unknown primary cancer is a hazardous diagnostic and limited therapeutic medical problem with too much variability. It is possible to design a standard procedure using the world-wide scientific literature, which could be able to decrease patient suffering and to avoid unnecessary sanitary costs, without diminishing survival. First of all we have conducted a retrospective descriptive study including all the patients with unknown primary neoplasms detected in our Internal Medicine service during 1994. We have met 18 cases, most of them adenocarcinoma and undifferentiated carcinoma, and hepatomegaly as clinical presentation. In 8 cases (44%) was the primary tumour site identified, mainly with CT. Only 3 (16%) patients were alive at the end of the study, with a mean survival of 5 months. The mean stay and time until diagnosis were 16.5 and 21.5 days respectively. Further studies will let us to asses the effectiveness of a theoretic diagnostic protocol.

Highly symmetriaal crystallization in six rectiinear and well-defined axes fouund in bovine cervical mucus obtained at oestrus: a finding / Cristaización alltamene simétrica con seis ejes rectilíneos y bien deefinidos hallada en moco cervical bovino obtenido en estro

Bovine cervical mucus (BCM) is important for selection and transport of spermatozoa. When air-dried, BCM obtained at oestrus exhibits arborescent crystallizations, among other arrangements. Considering the relevant endocrine and reproductive information indirectly obtained from BCM crystallization, a morphological investigation was carried out to study its crystalline patterns. BCM samples were collected from healthy Holstein Friesian heifers at oestrus, their crystalline patterns photographed and its morphology analyzed. The majority of the crystallizations obtained showed the typical tree-like patterns reported for BCM. However, a highly symmetrical arrangement was found, characterized by a star-like morphology with six straight, highly defined axes that protrude from the same central point, forming 60º angles. In terms of current knowledge, this short report is the first to show this crystallization geometry in BCM, which, additionally, is remarkably similar to P6B mucus reported for periovulatory human cervical mucus. Even though the role of mucus presenting this type of crystallization is as yet unknown for bovines, its possible functions are also briefly discussed here.

El moco cervical bovino es importante para la selección y el transporte espermático. El moco, obtenido durante el estro y secado al aire, exhibe cristalizaciones con formas principalmente arborescentes. Considerando la importante información endocrina y reproductiva que es posible obtener a partir de la cristalización del moco cervical, se efectuó una investigación morfológica con el propósito de estudiar sus patrones cristalinos. Las muestras de moco se obtuvieron de novillas Holstein Friesian en estro; posteriormente, los patrones de cristalización del moco fueron fotografiados para finalmente analizar su morfología. Las cristalizaciones obtenidas correspondieron a típicos patrones arboriformes previamente reportados. Sin embargo, lo que llamó la atención fue el hallazgo de un arreglo altamente simétrico en una novilla, caracterizado por una morfología similar a estrella con seis ejes rectos, bien definidos, que surgen desde el mismo punto central y forman ángulos de 60º. Según nuestro conocimiento, esta comunicación breve reporta por primera vez la presencia de dicha geometría de cristalización en vaquillas, la cual es muy semejante al patrón cristalino subtipo P6 reportado para el moco cervical perioBvulatorio humano. Si bien el rol ejercido por este tipo de cristalización de moco aún se desconoce en bovinos, se discuten aquí sus posibles funciones.

Gamete membrane fusion in hamster spermatozoa with reacted equatorial segment.

Mammalian spermatozoa must undergo many changes to be able to fertilize the oocyte. One of these changes, the acrosome reaction, has been established as a requisite for gamete membrane fusion to occur; it consists of the fusion and vesiculation of the sperm plasma membrane with the outer acrosomal membrane of the principal segment of the acrosome. Reaction of the equatorial segment has occasionally been observed. The objective of the present work was to determine whether the presence of the sperm plasma membrane over the equatorial segment is necessary for gamete membrane fusion to occur. Golden hamster spermatozoa were capacitated in vitro in TAPL 10K, and the maximum possible percentage of acrosome reaction was determined at 82.79% + 1.69% SD (P = 0.27; r = 0.21). Ultrastructural studies showed that 93.6% of the reacted spermatozoa in this population had their principal and equatorial segments reacted. The fertilizing ability of these spermatozoa was assayed using zona-free hamster oocytes. The percentage of fertilized ova obtained was 98.8% (308/312). Ultrastructural studies showed the presence of spermatozoa with reacted equatorial segment inside the cytoplasm of immature oocytes. The evidence presented in this work demonstrates that the plasma membrane of spermatozoa with reacted equatorial segment retains its ability to fuse with the oocyte.

The gamete membrane fusion test to assay the fertilizing ability of human spermatozoa.

The value of the gamete fusion test for the assessment of human spermatozoa is assessed. The factors influencing the test are discussed, including the conditions of heterologous fertilization using zona-free oocytes such as the nature of sperm preparation, sperm concentration and capacitation time, and the importance of albumin in the medium. The oocytes can be examined before or after fixation, and the spermatozoa around the eggs assessed for acrosome changes, while the number of sperm tails on the oocyte can be related to the number of chromatin decondensations. The test provides information on the fertilizing ability of spermatozoa of given individuals, and may prove of value in testing contraceptives.

Alkylating agents and mouse spermatogenesis: effects of a single dose of cyclophosphamide.

Cyclophosphamide (CFA) is one of the alkylating agents which has now been used with some success in the treatment of human neoplasias and renal disease. To evaluate how this drug could affect the seminiferous epithelium, a single dose of CFA (200 mg/kg/weight) was given to twenty adult mice (strain A/SW). The effect of the drug was compared with a control group to which physiological saline solution was injected. Mice were sacrificed by cervical dislocation at four different time intervals after the drug administration in order to evaluate the action of the drug in different stages of spermatogenesis. The effect of the drug was appreciated as soon as four days after its administration. The initial damage to the epithelium was characterized by vacuolization of the Sertoli cells. Of all germ cells, primary spermatocytes showed the highest sensitivity to the drug. A high percent of teratozoospermia in the experimental group, when compared to the control group, was observed at all time intervals. The way CFA affects the morphology of mammalian spermatozoa and the usefulness of the animal model presented are discussed.

Sperm binding to the human zona pellucida after migration through human cervical mucus.

During lactational amenorrhea a special type of cervical mucus, similar to that found during the luteal phase, is produced. This mucus, however, is able to support sperm migration. In the study described, the ability of spermatozoa to bind to the human zona pellucida (hZP) after migration through periovulatory and post-partum mucus was studied. Mucus was obtained from exclusively breastfeeding women in amenorrhea at 30, 60, 120 and 180 days post-partum. Periovulatory mucus samples from normally cycling women were used as a control. Flat capillary tubes were filled with BWW culture medium at the top and cervical mucus at the bottom. The tubes were immersed in a semen reservoir and the spermatozoa allowed to migrate through the mucus for 3 h into the culture media. Then the spermatozoa were coincubated with 3-4 hZP for 30 min and the number of bound spermatozoa per zona was counted. Periovulatory cervical mucus had an average Insler score of 14 +/- 0.5 as compared to 4.6 +/- 0.4 for post-partum mucus. Spermatozoa recovered from periovulatory mucus were always able to bind to the hZP in only 68 +/- 7% of the cases. Moreover, spermatozoa recovered from post-partum mucus bound to the ZP in lower numbers than did spermatozoa recovered fro periovulatory mucus (p < 0.03). These results suggest a greater ability of sperm-hZP binding after migration through periovulatory mucus and they also indicate that sperm binding to the ZP is possible even after sperm migration through a low quality mucus.

Human cervical mucus: relationship between biochemical characteristics and ability to allow migration of spermatozoa.

Cervical mucus is produced throughout the menstrual cycle. Sperm migration, however, is possible only during the periovulatory period of the cycle. Cervical mucus is also produced during the amenorrhoeic post-partum period. Post-partum mucus is very similar to luteal phase mucus except that it can allow sperm migration. In this study, mucus samples obtained from all these periods were classified according to their capacity to allow sperm migration. The biochemical characteristics of mucus samples that did (peri-ovulatory and 40% of post-partum samples) and did not (luteal and 60% of post-partum samples) allow sperm migration were then compared. Mucus samples with positive sperm migration showed the highest percentage of water and lowest protein and glycoprotein concentration (per ml of mucus). In addition, post-partum mucus samples with positive sperm migration showed lower concentrations of proteins and glycoproteins than post-partum mucus samples that did not allow sperm migration. However, the amount of glycoproteins per mg of protein was similar between post-partum samples that were positive and negative for sperm migration. These data suggest that the carbohydrate composition of the glycoproteins is playing a key role in the ability of cervical mucus to accept spermatozoa.

Human spermatozoa selected by Percoll gradient or swim-up are equally capable of binding to the human zona pellucida and undergoing the acrosome reaction.

Several techniques have been used for selecting motile spermatozoa including Percoll and albumin gradients, swim-up, and glass wool filtration. A high yield of motile spermatozoa as well as an enhancement of motility are the most desirable features of a practical method. An equally important consideration is whether or not these techniques select functionally normal spermatozoa. In this study we have compared two methods for separation of motile cells, swim-up and Percoll gradient. Normal semen samples from 12 different men were used in this study. Each sample was simultaneously processed by swim-up and Percoll gradient using modified Tyrode's medium. After the sperm concentration was adjusted to 1 x 10(7) spermatozoa/ml, the suspensions were incubated at 37 degrees C, 5% CO2 in air. In each suspension the percentage of sperm recovery, percentage of motile spermatozoa, percentage of acrosome reacted spermatozoa (either spontaneously or stimulated with human follicular fluid), percentage of zona-free hamster oocytes penetrated, and number of spermatozoa bound to the human zona pellucida were determined. The results obtained indicated that the percentage of sperm recovery was higher with the Percoll gradient than with the swim-up procedure (P less than 0.001). However, no significant differences were found between these two sperm populations in the percentage of motile cells, in the percentage of acrosome reacted spermatozoa, and in the percentage of zona-free hamster oocytes penetrated. In addition, the number of spermatozoa bound per zona pellucida was similar for spermatozoa selected by Percoll or swim-up. We conclude that there were no functional differences between the spermatozoa selected by either method.

Post-partum cervical mucus: biological and rheological properties.

In this study we have evaluated the score, sperm migration and ultrastructural characteristics of cervical mucus present in amenorrhoeic women under exclusive breastfeeding at 30, 60, 90, 120, 150 and 180 days post-partum. Periovulatory mucus samples from seven normally cycling women were used as a control. The average scores of post-partum and periovulatory mucus were 4.6 +/- 0.4 and 14.1 +/- 0.5 respectively. Twenty-one (39%) of the 54 post-partum cervical mucus samples and all (100%) periovulatory mucus samples allowed sperm migration. Positive sperm migration into post-partum mucus was observed at all time intervals studied. The only parameter that correlated with sperm migration into post-partum mucus was ferning formation. Sperm migration was obtained in all post-partum mucus samples with a score greater than 8, but samples with scores between 2 and 7 also showed sperm penetration. Scanning electron microscopic studies showed the characteristic spongy appearance of periovulatory mucus. Post-partum mucus was formed by a dense mesh (rocky appearance), when samples were generally unable to sustain sperm migration, but samples where sperm migration occurred showed small areas of spongy mucus mixed with areas in which a dense mesh and high cellularity was observed.

Inhibition of the acrosome reaction by trypsin inhibitors and prevention of penetration of spermatozoa through the human zona pellucida.

In this study we evaluated the effect of several trypsin inhibitors (p-aminobenzamidine: pAB; N-alpha-p-tosyl-L-lysine-chloromethyl-ketone: TLCK and p-nitrophenyl-p'-guanidino-benzoate: NPGM) on sperm binding and penetration of the human zona pellucida. Motile spermatozoa, selected by a two-step Percoll gradient, were incubated at 1 x 10(7) cells ml-1 at 37 degrees C and in 5% CO2 for 4.5 h. This was followed by the addition of 1 mmol pAB l-1 or phosphate-buffered saline (control) for 30 min. Three to four non-viable human oocytes were then added to each sperm suspension and incubated for 3 h. The numbers of spermatozoa bound to the human zona pellucida and in the perivitelline space were determined by phase contrast microscopy. The results showed that pAB significantly inhibited zona penetration by spermatozoa (56 +/- 8% oocytes penetrated, control versus 0 +/- 0% oocytes penetrated, pAB, mean +/- SEM), without modifying spermatozoa-zona pellucida binding. The inhibition of zona penetration was due to a block of the acrosome reaction normally induced by the human zona pellucida. In separate experiments, sperm suspensions pretreated with 1 mmol pAB l-1 or 10 mumol NPGB l-1 exhibited a marked decrease in the percentage of acrosome reactions on the zona surface (85 +/- 4% and 76 +/- 3% inhibition, respectively). In addition, the inhibitors prevented the acrosome reaction induced by human follicular fluid (percentage of acrosome-reacted spermatozoa: control 8 +/- 2; follicular fluid 25 +/- 3; pAB 6 +/- 2; NPGB 8 +/- 1; TLCK 12 +/- 2).(ABSTRACT TRUNCATED AT 250 WORDS)

First-trimester pregnancy loss and active Chlamydia trachomatis infection: correlation and ultrastructural evidence.

The incidence of Chlamydia trachomatis (Ct) infection and the possible correlation between couples presenting with first-trimester spontaneous abortions and active Ct infection was assessed. Additionally, the ability of Ct to infect zona-free hamster oocytes was explored by incubating the oocytes with spermatozoa from infected patients. A total of 961 women and 750 men consulting our reproductive medicine centre were screened for Ct using direct immunofluorescence. The general incidence of Ct infection was 9.4% in females (90 of 961) and 13.9% in males (104 of 750). In women with spontaneous abortions the incidence of Ct was 21.0% (14 of 66) compared with 8.9% (23 of 59) for women without spontaneous abortions and term pregnancies (chi-square, P < 0.05). When both partners of the couples were considered (one or both partners infected), the incidence rose to 68.8% (22 of 32) (chi-square, P < 0.001). In vitro studies using electron microscopy demonstrated the presence of Ct on the surface of and inside the oocyte. These results indicate a correlation between an active Ct infection and spontaneous abortion. Electron microscopy studies suggested the possibility of direct oocyte infection by Ct. Two models are proposed for the pathogenesis of Ct-related early abortions: (i) direct zygote infection, and (ii) immune response to heat shock proteins expressed by the zygote and triggered by previous Ct infections.

Selection of morphologically abnormal sperm by human cervical mucus.

The important role of cervical mucus from a reproduction standpoint is the transport and selection of spermatozoa. The study of the fertilizing ability of human spermatozoa by the use of zona-free hamster oocytes has shown that morphologically abnormal sperm can fuse with the zona-free hamster oocyte. The high proportion of morphologically abnormal spermatozoa present in human semen is significantly reduced after sperm migration through cervical mucus. The mucus, while a favorable environment for sperm survival, does not seem to contribute to the occurrence of sperm capacitation and acrosome reaction.