Normal and abnormal appearance of fetal ganglionic eminence on second-trimester three-dimensional ultrasound.

OBJECTIVES: To describe the appearance and size of the ganglionic eminence (GE) in normal fetuses on midtrimester three-dimensional (3D) neurosonography and to report on the association between GE alterations (cavitation or enlargement) and malformation of cortical development (MCD). METHODS: This was a prospective multicenter cohort study of normal fetuses and a retrospective analysis of pathological cases with MCD. From January 2022 to June 2022, patients attending our tertiary centers for an expert fetal brain scan were recruited for the purpose of the study. A 3D volume of the fetal head, starting from the sagittal plane, was acquired in apparently normal fetuses using a transabdominal or transvaginal approach. Stored volume datasets were then evaluated independently by two expert operators. Two measurements (longitudinal diameter and transverse diameter) of the GE in the coronal view were obtained twice by each operator. Intra- and interobserver measurement variation was calculated. Reference ranges for GE measurements were calculated in the normal population. A previously stored volume dataset of 60 cases with MCD was also analyzed independently by the two operators using the same method in order to assess if GE abnormalities (cavitation or enlargement) were present. Postnatal follow-up was obtained in all cases. RESULTS: In the study period, 160 normal fetuses between 19 and 22 weeks of gestation were included in the study. The GE was visible in the coronal plane on 3D neurosonography in 144 (90%) cases and was not clearly visible in the remaining 16 (10%) cases. The intra- and interobserver agreement was almost perfect for the longitudinal diameter, with an intraclass correlation coefficient (ICC) of 0.90 (95% CI, 0.83-0.93) and 0.90 (95% CI, 0.86-0.92), respectively, and substantial for the transverse diameter, with an ICC of 0.80 (95% CI, 0.70-0.87) and 0.64 (95% CI, 0.53-0.72), respectively. A retrospective analysis of 50 cases with MCD in the second trimester showed that GE enlargement was present in 12 cases and GE cavitation was present in four cases. CONCLUSIONS: Systematic assessment of the GE in fetuses at 19-22 weeks of gestation is feasible on 3D neurosonography, with good reproducibility in normal cases. Cavitation or enlargement of the GE can be demonstrated in fetuses with MCD. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Adenosine A1 and A2a receptors modulate the nitrergic system in cell culture from dorsomedial medulla oblongata.

Adenosine and nitric oxide act on the fine-tuning regulation of neural cardiovascular control in the nucleus tractus solitarius (NTS). Although the interaction between adenosine and NO is well known in the periphery, the mechanisms by which adenosine interferes in the dynamics of nitrergic neurotransmission, related to neural control of circulation, are not completely understood and might be relevant for individuals predisposed to hypertension. In this study we evaluate the interaction between adenosinergic and nitrergic systems in cell culture from the dorsomedial medulla oblongata of Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR). Using quantification of nitrite levels, RT-PCR analysis and RNA interference we demonstrate that adenosine A1 (A1R) and A2a receptor (A2aR) agonists induce a concentration-dependent decrease and increase of nitrite and nNOS mRNA levels in cultured cells from WKY and SHR, respectively. These effects in nitrite levels are attenuated by the administration of A1R and A2aR selective antagonists, CPT and ZM 241385. Furthermore, knockdown of A1R and A2aR show an increase and decrease of nNOS mRNA levels, respectively. Pretreatment with the nonselective inhibitor of NOS, L-NAME, abolishes nitrite-increased levels triggered by CGS 21680 in WKY and SHR cells. Finally, it is shown that the cAMP-PKA pathway is involved in A1R and A2aR-mediated decrease and increase in nitrite levels in SHR and WKY cells. Our results highlight the influence of adenosine on nitric oxide levels in cultured cells from dorsal medulla oblongata of neonate WKY and SHR rats. In part, the modulatory profile is different in the SHR strain.

Effects of frutalin and doxorubicin on growth, ultrastructure and gene expression in goat secondary follicles cultured in vitro.

This study evaluated the effects of frutalin (0.6, 6.0 or 60.0 µg/mL) and doxorubicin (0.3 µg/mL) on survival, growth and ultrastructure of in-vitro cultured goat secondary follicles. The effects of these substances on the levels of mRNA for Casp3, Casp6, Bax, and Bcl2 were also investigated. Results showed that, after 6 days of culture, frutalin or doxorubicin reduced the percentage of normal follicles (P < 0.05), but doxorubicin had higher toxicity than frutalin. Except for follicles cultured with 0.6 µg/mL frutalin, follicular growth rate was reduced after culture with doxorubicin or frutalin (P < 0.05). The presence doxorubicin or 60.0 µg/mL frutalin increased the levels of mRNA for Casp3, Casp6, Bax, and Bcl2 (P < 0.05). Higher mRNA levels for Casp3, Casp6 and Bax were found in follicles cultured with doxorubicin, but higher levels of Bcl2 mRNA were found in follicles cultured with frutalin (P < 0.05). In conclusion, frutalin has lower toxic effects than doxorubicin on secondary follicles cultured in vitro.

A case of late orthostatic headache secondary to lumbar hidden dural fistula 20 months after epidural anesthesia.

The clinical recognition of CSF fistula is a clinical challenge. We report the case of a young woman, who presented with a late orthostatic headache 20 months after epidural anesthesia. She developed a lumbar dural fistula of CSF confirmed in myelography CT scanning and treated successfully with epidural blood patch.

Ethanol addition enhances acid treatment to eliminate Lactobacillus fermentum from the fermentation process for fuel ethanol production.

Fermentation is one of the most critical steps of the fuel ethanol production and it is directly influenced by the fermentation system, selected yeast, and bacterial contamination, especially from the genus Lactobacillus. To control the contamination, the industry applies antibiotics and biocides; however, these substances can result in an increased cost and environmental problems. The use of the acid treatment of cells (water-diluted sulphuric acid, adjusted to pH 2·0-2·5) between the fermentation cycles is not always effective to combat the bacterial contamination. In this context, this study aimed to evaluate the effect of ethanol addition to the acid treatment to control the bacterial growth in a fed-batch system with cell recycling, using the industrial yeast strain Saccharomyces cerevisiae PE-2. When only the acid treatment was used, the population of Lactobacillus fermentum had a 3-log reduction at the end of the sixth fermentation cycle; however, when 5% of ethanol was added to the acid solution, the viability of the bacterium was completely lost even after the first round of cell treatment. The acid treatment +5% ethanol was able to kill L. fermentum cells without affecting the ethanol yield and with a low residual sugar concentration in the fermented must. SIGNIFICANCE AND IMPACT OF THE STUDY: In Brazilian ethanol-producing industry, water-diluted sulphuric acid is used to treat the cell mass at low pH (2·0) between the fermentative cycles. This procedure reduces the number of Lactobacillus fermentum from 107 to 104  CFU per ml. However, the addition of 5% ethanol to the acid treatment causes the complete loss of bacterial cell viability in fed-batch fermentation with six cell recycles. The ethanol yield and yeast cell viability are not affected. These data indicate the feasibility of adding ethanol to the acid solution replacing the antibiotic use, offering a low cost and a low amount of residue in the biomass.

Bioactive compounds from extra virgin olive oils: Correlation between phenolic content and oxidative stress cell protection.

When compared with other edible vegetable oils, the extra virgin olive oil (EVOO) exhibits excellent nutritional properties due to the presence of biophenolic compounds. Although they constitute only a very small amount of the unsaponifiable fraction of EVOO, biophenols strongly contribute to the sensorial properties of this precious food conferring it, for example, the bitter or pungent taste. Furthermore, it has been found that biophenols possess beneficial effects against many human pathologies such as oxidative stress, inflammation, cardiovascular diseases, cancer and aging-related illness. In the present work, the biophenolic content of 51 Italian and Spanish EVOOs was qualitatively and quantitatively identified and their antioxidant ability analyzed by oxygen radical absorbance capacity (ORAC) assay. Results indicated that the maximum relationship can be found if the ORAC value is correlated with the concentration of the large family composed by ligstroside and oleuropein derivatives together with their degradation products, hydroxytyrosol and tyrosol. Then, selected biophenolic extracts were tested in NIH-3T3 cell line to verify their ability in the recovery of the oxidative stress revealed by DCFH-DA assay. Results were linearly correlated with the concentration of ligstroside aglycone (aldehyde and hydroxyl form).

Integrated Analyses of Cuticular Hydrocarbons, Chromosome and mtDNA in the Neotropical Social Wasp Mischocyttarus consimilis Zikán (Hymenoptera, Vespidae).

In the present work, we explored multiple data from different biological levels such as cuticular hydrocarbons, chromosomal features, and mtDNA sequences in the Neotropical social wasp Mischocyttarus consimilis (J.F. Zikán). Particularly, we explored the genetic and chemical differentiation level within and between populations of this insect. Our dataset revealed shallow intraspecific differentiation in M. consimilis. The similarity among the analyzed samples can probably be due to the geographical proximity where the colonies were sampled, and we argue that Paraná River did not contribute effectively as a historical barrier to this wasp.

The endocannabinoid system: A novel player in human placentation.

Cannabis sativa is the most consumed illegal drug around the world. Its consumption during pregnancy is associated with gestational complications, particularly with fetal growth restriction. Endocannabinoids (eCBs) are lipid molecules that act by activating the G-protein coupled cannabinoid receptors, which are also target of the phytocannabinoid Δ(9)-tetrahydrocannabinol (THC). The endocannabinoid system (ECS) participates in distinct biological processes, including pain, inflammation, neuroprotection, and several reproductive events. In addition, an abnormal expression of ECS is associated with infertility and miscarriages. This manuscript will review and discuss the expression of ECS in normal and pathological human placentas, and the role of eCBs and THC in trophoblast proliferation, apoptosis, differentiation, and function. The current evidence points towards a role of ECS in human placentation, shedding light on the contribution of the eCBs in the coordination of human placentation, and in the cellular mechanisms underlying the deleterious effects of cannabis consumption during pregnancy.

The endocannabinoid 2-arachidonoylglycerol dysregulates the synthesis of proteins by the human syncytiotrophoblast.

In recent years, endocannabinoids emerged as new players in various reproductive events. Recently, we demonstrated the involvement of 2-arachidonoylglycerol (2-AG) in human cytotrophoblast apoptosis and syncytialization. However, 2-AG impact in hormone production by the syncytiotrophoblast (hST) was never studied. In this work, we demonstrate that 2-AG activates cannabinoid (CB) receptors, exerting an inhibitory action on cyclic AMP/protein kinase A (cAMP/PKA) and mitogen-activated protein kinase (MAPK) p38 pathways, and enhancing ERK 1/2 phosphorylation. Furthermore, 2-AG affects the synthesis of human chorionic gonadotropin (hCG), leptin, aromatase, 3-ß-hydroxysteroid dehydrogenase (3-ß-HSD), and placental protein 13 (PP13). These 2-AG effects are mediated by the activation of CB receptors, in a mechanism that may involve p38, ERK 1/2 and cAMP/PKA pathways, which participate in the regulation of placental proteins expression. To our knowledge, this is the first study that associates the endocannabinoid signalling and endocrine placental function, shedding light on a role for 2-AG in the complex network of molecules that orchestrate the production of placental proteins essential for the gestational success.

Scrutinising the regulators of syncytialization and their expression in pregnancy-related conditions.

The placenta is important for the success of gestation and foetal development. In fact, this specialized pregnancy organ is essential for foetal nourishment, support, and protection. In the placenta, there are different cell populations, including four subtypes of trophoblasts. Cytotrophoblasts fuse and differentiate into the multinucleated syncytiotrophoblast (syncytialization). Syncytialization is a hallmark of placentation and is highly regulated by numerous molecules with distinct roles. Placentas from pregnancies complicated by preeclampsia, intrauterine growth restriction or trisomy 21 have been associated with a defective syncytialization and an altered expression of its modulators. This work proposes to review the molecules that promote or inhibit both fusion and biochemical differentiation of cytotrophoblasts. Moreover, it will also analyse the syncytialization modulators abnormally expressed in pathological placentas, highlighting the molecules that may contribute to the aetiology of these diseases.

Neotropical Polistinae (Vespidae) and the Progression Rule Principle: the Round-Trip Hypothesis.

The progression rule principle is based on the relation between centers of origin and basal forms, and the prediction that recently colonized areas are where novelties commonly occur. Using this concept as the null hypothesis, the aim of the present study was to test whether intuitive predictions of this model are confirmed in the Neotropical paper wasps, a group fairly studied through phylogenetic frameworks. The analyses consisted of a careful review of the distribution of different wasps of the subfamily Polistinae with available phylogenies and the association of this information with colonization routes. This procedure allowed the determination of a two-step colonization process in the Neotropical region based on the progression rule principle, for which the round-trip hypothesis is proposed. The first route (east to west) is seen in a small group of Polistes. This route is rare but strengthens the arising of paper wasps in the Americas in a Gondwanan scenario. The second route (west to east) is remarkably repeated in several other lineages. Thus, the northwestern Neotropics, mainly Amazon Forest, is proposed as the major center of origins for living Neotropical Polistinae and the round-trip hypothesis may explain both earlier and later colonization routes of the paper wasps analyzed.

The endocannabinoid anandamide affects the synthesis of human syncytiotrophoblast-related proteins.

The human syncytiotrophoblast (hST) has a major role in the production of important placental hormones. Several molecules regulate hST endocrine function but the role of endocannabinoids in this process is still unknown. Here, we report that the endocannabinoid anandamide (AEA) decreased cAMP levels, impaired human chorionic gonadotropin secretion, placental alkaline phosphatase activity and decreased aromatase mRNA levels and protein expression, through cannabinoid (CB) receptor activation. AEA also downregulated leptin and placental protein 13 transcription, though via a CB receptor-independent mechanism. All this evidence suggests AEA is a novel modulator of hormone synthesis by the syncytiotrophoblast, supporting the importance of the endocannabinoid signalling in placental function.

The psychoactive compound of Cannabis sativa, Δ(9)-tetrahydrocannabinol (THC) inhibits the human trophoblast cell turnover.

The noxious effects of cannabis consumption for fertility and pregnancy outcome are recognized for years. Its consumption during gestation is associated with alterations in foetal growth, low birth weight and preterm labor. The main psychoactive molecule of cannabis, Δ(9)-tetrahydrocannabinol (THC) impairs the production of reproductive hormones and is also able to cross the placenta barrier. However, its effect on the main placental cells, the trophoblasts, are unknown. Actually, the role of THC in cell survival/death of primary human cytotrophoblasts (CTs) and syncytiotrophoblasts (STs) and in the syncytialization process remains to be explored. Here, we show that THC has a dual effect, enhancing MTT metabolism at low concentrations, whereas higher doses decreased cell viability, on both trophoblast phenotypes, though the effects on STs were more evident. THC also diminished the generation of oxidative and nitrative stress and the oxidized form of glutathione, whereas the reduced form of this tripeptide was increased, suggesting that THC prevents ST cell death due to an antioxidant effect. Moreover, this compound enhanced the mitochondrial function of STs, as observed by the increased MTT metabolism and intracellular ATP levels. These effects were independent of cannabinoid receptors activation. Besides, THC impaired CT differentiation into STs, since it decreased the expression of biochemical and morphological biomarkers of syncytialization, through a cannabinoid receptor-dependent mechanism. Together, these results suggest that THC interferes with trophoblast turnover, preventing trophoblast cell death and differentiation, and contribute to disclose the cellular mechanisms that lead to pregnancy complications in women that consume cannabis-derived drugs during gestation.

2-Arachidonoylglycerol impairs human cytotrophoblast cells syncytialization: influence of endocannabinoid signalling in placental development.

A balanced cytotrophoblast cell turnover is crucial for placental development and anomalies in this process associated with gestational diseases. The endocannabinoid system (ECS) has emerged as a new player in several biological processes. However, its influence during placental development is still unknown. We report here the expression of the endocannabinoid 2-arachidonoylglycerol (2-AG) main metabolic enzymes in human cytotrophoblasts and syncytiotrophoblast. We also showed that 2-AG induced a decrease in placental alkaline phosphatase activity, human chorionic gonadotropin secretion and Leptin mRNA levels. Moreover, 2-AG reduced glial cell missing 1 and syncytin-2 transcription and the number of nuclei in syncytium. These effects were mediated by cannabinoid receptors and may result from 2-AG inhibition of the cAMP/PKA signalling pathway. Our data suggest that 2-AG may interfere with the biochemical and morphological differentiation of human cytotrophoblasts, through a CB receptor-dependent mechanism, shedding light on a role for the ECS in placental development.

The endocannabinoid anandamide induces apoptosis in cytotrophoblast cells: involvement of both mitochondrial and death receptor pathways.

INTRODUCTION: A balanced proliferation, apoptosis and differentiation in trophoblast cells of the human placenta is crucial for a proper placental development. Alteration in trophoblast apoptosis and differentiation are associated with gestational-related complications, such as preeclampsia, intrauterine growth restriction or miscarriages. The endocannabinoids (eCBs) have been recognized as new interveners in pregnancy events such as implantation and decidualization. However, their importance in placentation is poorly understood. We hypothesise that these novel lipid mediators may intervene in cytotrophoblast apoptosis and, concomitantly, have a role during placental development. METHODS: primary human cytotrophoblasts (hCTs) and the human trophoblast-like choriocarcinoma cell line BeWo cells were exposed to Anandamide (AEA). It was investigated the cellular pathways involved in cell death, by the assessment of cell morphology, caspases activity, mitochondrial membrane potential (Δψm), reactive oxygen/nitrogen species (ROS/RNS) and western blot of cleaved Poly (ADP-ribose) polymerase 1 (PARP-1), truncated Bid (t-Bid) and IκB-α. RESULTS: AEA decreased hCTs viability and induced morphological features of apoptosis (chromatin condensation and fragmentation), caspase-3/7 activation and PARP-1 cleavage. In BeWo, AEA also increased the activities of caspase-3/7 and 9, induced loss in Δψm and production of ROS/RNS. These effects were reversed by either CB1 or CB2 antagonists, whereas the increase in caspase-3/7 activity was only reversed with CB2 blockage. AEA-treated cells showed increased caspase-8 activation and formation of t-Bid, suggesting the interplay between intrinsic and extrinsic apoptotic pathways. AEA also increased IκB-α expression, a NF-κB regulatory protein. CONCLUSION: Our results highlight the importance of eCBs in cytotrophoblast cell apoptosis and indicate that a crosstalk between intrinsic and extrinsic apoptotic pathways is involved in AEA-induced effects.

Transient receptor potential vanilloid 1 is expressed in human cytotrophoblasts: induction of cell apoptosis and impairment of syncytialization.

The normal development of placenta relies essentially on a balanced proliferation, differentiation and apoptosis of cytotrophoblasts. These processes are tightly regulated by several hormones, cytokines, lipids and other molecules and anomalies in these events are associated with gestational complications. The cation channel transient receptor potential vanilloid 1 (TRPV1) is expressed in several organs and tissues and it participates in cellular events like nociception, inflammation and cell death. However, the expression and importance of this receptor in human placenta still remains unknown. In this work, we found that TRPV1 is expressed in human cytotrophoblasts and syncytiotrophoblasts. Furthermore, the TRPV1 agonists capsaicin and anandamide decreased cytotrophoblast viability and induced morphological alterations, such as chromatin condensation and fragmentation, which suggest the occurrence of apoptosis. Also, both TRPV1 agonists induced a loss of mitochondrial membrane potential and an increase of caspase 3/7 activity and production of reactive species of oxygen and nitrogen. Furthermore, capsaicin (10 µM) impaired the spontaneous in vitro differentiation of cytotrophoblasts into syncytiotrophoblasts by triggering TRPV1, as observed by the decrease in placental alkaline phosphatase activity and in human chorionic gonadotropin secretion. On the other hand, anandamide decreased placental alkaline phosphatase activity via a TRPV1-independent mechanism but did not influence the secretion of human chorionic gonadotropin. In conclusion, we showed that TRPV1 is expressed in human cytotrophoblasts and syncytiotrophoblasts and also reported the involvement of this receptor in cytotrophoblast apoptosis and differentiation.

Specialist nurse in Europe: education, regulation and role.

BACKGROUND: The concept of a 'specialist nurse' has existed for many years and related education programmes are proliferating. However, while literature clearly outlines the roles and practice of registered nurses and advanced practice nurses, those of specialist nurses remain unclear and nursing specializations across Europe need clarifying. AIM: This pilot study aimed to explore the competencies, education requirements and regulation of specialist nurses in Europe. DESIGN: A descriptive cross-sectional survey. METHODS: An online questionnaire named 'Specialist nurse and specialization in Europe' was sent to 550 members of the European Federation of Nurse Educators and ten members of the European Specialist Nurses Organizations. Snowball sampling was then used to build a convenience sample of nurse educators, clinical nurses and specialist nurses, national nursing association members, and chief nursing officers from all European countries. Besides quantitative aspects, responses to open-ended questions were analysed using a qualitative content analysis process. RESULTS: A total of 77 experts from 29 European countries responded to the questionnaire. Findings highlighted variations in titles, levels and length of education, certification, regulation and scope of practice for specialized nurses in Europe. Analysis of the promoted competencies revealed dominant clinical and technical aspects of the role with a high level of knowledge. CONCLUSIONS: The study emphasized the need to improve standards for education, certification and regulation for specialist nurses. Interpretation of the role and competencies is diverse with a weak presence of health policy that would enhance and develop the specialities. IMPLICATIONS FOR NURSING AND HEALTH POLICY: To address the current lack of provisions for automatic recognition of specialist nurses, common training frameworks corresponding to the relevant level of the European Qualifications Framework should promote lifelong learning and mobility, and enhance levels of health care and patient safety.

Caracterização do insumo ibuprofeno e a correlação com propriedades de dissolução e de fluxo / Characterization of ibuprofen raw material and correlation with dissolution and flow properties

Ibuprofen is a moderately active non-steroidal anti-inflammatorydrug, derived from β-phenylpropionic acid. Its analgesic action, which is related to its anti-inflammatoryproperties, is due to a decrease in the production of enzymes cyclo-oxygenase-1 (COX-1) and cyclo-oxygenase-2 (COX-2). Ibuprofen exhibits distinct morphologies when crystallized under different conditions. In this study, the characteristics of the ibuprofen raw material and their impact on drug dissolution and processing properties were analyzed. Samples of raw ibuprofen from 3 different manufacturers were characterized by a variety of techniques. The analysis confirmed that all 3 samples exhibited the same crystalline form; thus, polymorphism could be discarded as one of the causes of any variation in performance of the drug. The results showed that the physical characteristics of each sample influenced its flow and dissolution properties. In fact, there was a detectable variation in the physical characteristics of the drug among the 3 different manufacturers. This demonstrates the importance of testing the characteristics of the drug raw material in order to correlate them with its performance in processing and eventual use, enabling pharmacotechnical improvement and development...

O ibuprofeno é um agente anti-inflamatório não esteróide, derivado do ácido fenilpropiônico que possui atividade anti-inflamatória de ação moderada. Sua ação analgésica está relacionada às propriedades anti-inflamatórias devido à redução da produção da ciclooxigenase-1 (COX-1) e da ciclooxigenase-2 (COX-2). O ibuprofeno exibe diferentes morfologias quando cristalizado em diferentes solventes. Neste estudo, se avaliaram as características de matérias-primas do ibuprofeno e o impacto destas nas propriedades de dissolução e processamento. Foram avaliadas três matérias-primas do ibuprofeno de três diferentes fabricantes, utilizando variadas técnicas de caracterização. As análises confirmaram que todas apresentavam a mesma forma cristalina do ibuprofeno; assim, o polimorfismo foi descartado como uma das causas de influência na dissolução e no fluxo do fármaco. Os resultados mostraram que características físicas da matéria-prima ibuprofeno tiveram impacto nas propriedades de fluxo e dissolução e que existe uma variabilidade das características físicas do fármaco entre diferentes fabricantes. Isto mostra a importância da avaliação de características da matéria-prima para correlacioná-las com propriedades de desempenho, possibilitando o desenvolvimento e melhoramento farmacotécnico...

Rat spontaneous foetal resorption: altered α2-macroglobulin levels and uNK cell number.

During rat pregnancy, some of the foetoplacental units undergo complete spontaneous resorption while the adjacent units remain unaffected. In an attempt to clarify the mechanisms implicated in this spontaneous resorption, implantation units from days 14 and 16 of pregnancy were examined. The number of implantation sites and resorption units was recorded, and uterine paraffin sections were stained with haematoxylin and eosin for the evaluation of tissue morphology. The incidence of resorption was about 9.2 % on day 14 and 8.2 % on day 16. Perforin and active caspase-3 immunostaining were performed for localization and characterization of uterine natural killer (uNK) and apoptotic cells, respectively. The α2-macroglobulin (α2-MG) expression was examined by in situ hybridization, immunohistochemistry and its levels quantified by enzyme-linked immunosorbent assay. A reduction in α2-MG decidual levels in resorpted units was observed when compared to normal implantation units in both days. This potent protease inhibitor is the major product secreted by the mesometrial decidual tissue and may constitute an indicator of maternal tissues remodelling abnormalities. Besides the decreased α2-MG levels, an increase in uNK cell number was found in resorption units. The decreased α2-MG levels may be related to the aberrant control of trophoblast invasion that may activate uNK cells. The elucidation of the mechanisms underlying natural pregnancy loss in rat may contribute for the clarification of the "vanishing twin" phenomenon that occurs in human pregnancy.