Genital Tract Organs Research Articles

PP 2.15 – 00169 Macrophages are the primary source of virus in semen and male genital tract organs in acutely and chronically infected rhesus macaques

PP 2.15 – 00169 Macrophages are the primary source of virus in semen and male genital tract organs in acutely and chronically infected rhesus macaques

HIV Compartmentalization in Male Genital Tract: Relevance for Viral Eradication

Abstract Human immunodeficiency virus (HIV) has been shown to evolve independently in different anatomical compartments. Characterizing HIV genetic evolution in different tissues and cells provides insights into the mechanisms that maintain the viral reservoir. HIV compartmentalization has been well documented in the semen but rarely in male genital tract (MGT) organs. The precise mechanisms that result in the development of HIV compartmentalization in multiple genitourinary sites have been poorly explored due to the difficulty in accessing these tissues. Based on evidence from lymph nodes and gut tissues, mechanisms that may influence compartmentalization include immune pressures, local concentrations of antiviral drugs, clonal expansion of different cell types and inflammation that alters the cellular microenvironment. We reviewed phylogenetic evidences supporting viral compartmentalization between the blood and multiple genitourinary sites in HIV-infected people. Characterizing distinct viral sub-populations enhances our overall understanding of the HIV reservoir in MGT and could ultimately lead to the development of novel therapies to eradicate the virus in tissues.

Manejo clínico de DIP / DIPA doença inflamatória pélvica e de repetição: uma revisão narrativa

Objetivo: Revisar sobre o manejo clínico de doença inflamatória pélvica e de repetição (DIP/DIPA). Revisão Bibliográfica: A DIP é uma infecção que se origina no trato genital inferior e que em muitos momentos pode atingir os órgãos do trato genital superior feminino, como o endométrio, tubas uterinas ou ovários. A maior prevalência de faixa etária é em mulheres que se encontram sexualmente ativas entre 15-24 anos de idade. É uma doença que se tratada no início consegue minimizar os prejuízos para a saúde da mulher. Se não tratada, a doença pode causar afetar o transporte dos óvulos e dos espermatozoides, acarretando dificuldades para a mulher engravidar ou contribui para chances de uma gestação ectópica. O tratamento da doença inicialmente é feito com o uso de antibióticos orais e intramusculares, caso a paciente apresente quadro de infecção, faz-se necessário a internação para uso de antibióticos endovenosos, e em alguns casos procedimento cirúrgico sendo preciso estabelecer repouso físico e sexual durante o tratamento. Considerações finais: Por se tratar de uma doença de clínica com variações, e em algumas situações assintomática, preconiza a dificuldade de se diagnosticar no início, para que tenha um tratamento adequado e eficiente a natureza da doença.

Secondary Tumors of the Gynecologic Tract: A Clinicopathologic Analysis.

Although the spread of extragenital tumors to individual female genital tract organs, particularly the ovary, has been much studied, histologic data with regard to secondary tumors involving the whole gynecologic tract are largely lacking. Thus, the aim of the study was to investigate the pathologic and clinical features of these tumors in order to better understand their features. This is a retrospective study of 196 secondary lesions involving the gynecologic tract. The parameters studied were the primary site, its histologic type and grade, the presence of mucous production, the type of secondary involvement, defined as distant metastasis, direct extension or locoregional recurrence, and the time to metastasis. Organs involved were the ovary (50%), the vagina (22%), the myometrium (10.7%), the cervix (10.2%), the endometrium (3.6%), the vulva (2%), and the Fallopian tube (1.5%). Most often, primary tumors were colorectal (39.8%), endometrial (15.3%), breast (12.7%), ovarian (10.7%), and gastric (5.6%). Secondary tumors were metachronous in 43.9% of the cases with a mean time to recurrence of 55.5 mo. Distant metastases were the most common type of secondary involvement (64.8%), followed by direct extension (19.9%) and local recurrence (15.3%). Gastrointestinal tumors involved mostly the ovaries, endometrial tumors the vagina, ovarian tumors the myometrium, and urothelial tumors the cervix/vagina (P<0.0001). Vaginal lesions endometrial origin presented with only superficial invasion (P=0.0002). The primary tumor's features dictate a different pattern of secondary involvement of the gynecologic tract. Endometrial tumors produce mostly superficial vaginal recurrences, mucus-producing gastrointestinal tumors present with ovarian metastases, whereas breast tumors affect the entire gynecologic tract and present the tumors with the most late recurrences.

Screening for Mollicutes microorganisms in perinatal calf mortality cases in Polish dairy herds.

Perinatal calf mortality in dairy herds has been reported worldwide. The etiology of stillbirth is multifactorial, and can be caused by various species of bacteria and environmental factors. Among them some potential pathogens from the Mollicutes class such as Mycoplasma (M.) spp. and Ureaplasma (U.) diversum can be isolated from the bovine genital tract and other organs of the suspected cattle. The aim of this study was to evaluate if the bacteria belonging to the Molli- cutes class i.e. M. bovis, M. bovigenitalium, M. canadense, M. canis, M. arginini, M. bovirhinis, M. dispar, M. alkalescens and U. diversum could have an impact on perinatal calf mortality in selected Polish dairy farms. The material was: 121 stillborn calves (SB), 21 live born calves (C) and 131 cows (dams) from 30 Polish Holstein-Friesian herds. Samples were examined from all the SB calves' and six control euthanized calves' abomasal contents and lung samples collected during necropsy, and from the dams' serum and placenta. In dams the serological ELISA, and in calves and placenta samples molecular PCR/denaturing gradient gel electrophoresis, methods were used. Screening of dams' sera for antibodies to M. bovis (ELISA) showed seven dams positive for M. bovis, whereas none of the nine examined Mollicutes microorganisms were detected in the placenta and calves.

Genital and reproductive organ complications of Crohn disease: technical considerations as it relates to perianal disease, imaging features, and implications on management.

A relatively large proportion of patients with Crohn disease (CD) develop complications including abscess formation, stricture, and penetrating disease. A subset of patients will have genital and reproductive organ involvement of CD, resulting in significant morbidity. These special circumstances create unique management challenges that must be tailored to the activity, location, and extent of disease. Familiarity with the epidemiology, pathogenesis, imaging features, and treatment strategies for patients with genital CD can aid imaging diagnoses and guide appropriate patient management. The purpose of this study is to illustrate the spectrum of CD in the genital tract and reproductive organs and discuss the complex management strategies in these patients as it relates to imaging. Given the impact on patient outcome and treatment planning, familiarity with the epidemiology, pathogenesis, imaging features, and treatment of patients with genital Crohn disease can aid radiologic diagnoses and guide appropriate patient management.

Preclinical In‐vivo Safety Evaluation of Concanavalin A‐based Nanomicrobicide in Female Mouse Reproductive Tract

ObjectiveTenofovir (TFV) loaded Concanavalin A nanoparticles (ConA‐NPs) was recently synthesized as mannose sensitive nanomicrobicide template for the prevention of HIV/AIDS transmission. To advance into clinical trials, such nanomicrobicide must be evaluated in preclinical safety and efficacy models. This study aims at examining the mucosal safety of these specific ConA‐NPs in the female mouse reproductive tract.MethodTFV loaded ConA‐NPs (~ 670 ± 234 nm, −15 ± 0.55 mV) were prepared via the “layer‐by‐layer” technology by coating a core template, calcium carbonate (CaCO3) crystal, with Con A crosslinked with glycogen. Pre‐clinical safety studies of intravaginally administered TFV loaded ConA‐NPs (100 mg/kg) were performed using a female mouse model C57Bl6. Mouse cervicovaginal lavage (CVL) and tissues (CVT) were collected 24h after a single application. Changes in the levels of inflammatory cytokines (IL‐1l, IL‐1β, IL‐6, IL‐7, IP‐10, MKC, and TNF‐l) were quantitated by a high‐sensitivity multiplexed bead‐based immunoassay. The histopathology of the genital tract (vagina, cervix, uterus, and ovary), rectum and other major organs (spleen, lung, liver, kidney, heart, brain) was studied using Hematoxylin &amp; Eosin staining. The vaginal tissues were evaluated for localized immune cells (lymphocytes) infiltration by immunohistochemical staining for CD45.ResultsAfter 24h exposure to these NPs, the basal levels of proinflammatory cytokines (IL‐1l, IL‐1β, IL‐6, IL‐7, IP‐10, MKC, and TNF‐l) in mouse CVL and CVT increased 3 – 56 fold and 1.2 – 5.2 fold, respectively when compared to phosphate buffered saline (PBS) used as a negative control. The induced inflammation was associated with the infiltration of immune cells to the vaginal epithelium. The histological analysis of the reproductive tract revealed signs of epithelial disruption in the vagina. However, all other tissues were histologically similar to control tissue at 24 h post application.ConclusionThese experiments showed that the present ConA‐NPs are cytotoxic to the genital tract epithelial cells at 100 mg/kg. These data suggest the need for further preclinical studies to determine the maximum tolerable dose of the nano formulation for vaginal application.Support or Funding InformationThe project was supported by Award Number RO1 AI087304 from the National Institutes of Allergy and Infectious Diseases (Bethesda, MD, USA). The content is the sole responsibility of the authors and does not necessarily represent the official views of the National Institutes of Allergy and Infectious Diseases or the National Institutes of Health.

Clinical Efficacy of Placentrex Injection in Pelvic Inflammatory Disease

Pelvic inflammatory disease (PID) is one of the most frequent infections seen in reproductive age group and is associated with major clinical and pelvic health problem. It is Infection & inflammation of upper genital tract organs typically involving fallopian tubes, ovaries & surrounding structures. PID is polymicrobial in nature and is associated with different etiological agents. Clinical presentations may vary from mild to severe. No specific signs and symptoms are pathognomic of PID. Laboratory tests are also poor predictors of PID. There may be subclinical symptoms and patient later may present with infertility. CDC recommends treatment for even mild cases of PID. Therapeutic goal in management of PID is to prevent chronic residual disease. Failure of antibiotic therapy to prevent sequelae of salpingitis reflects the emphasis of additional therapy along with antibiotics. Placentrex is a drug containing Peptides (FNP-III, CRF), Nucleotides (PDRN) & Glutamate and is derived from an extract of fresh term, healthy, human placenta. It has significant anti inflammatory effect involving chemical mediators of immunological response. Effect of placentrex is well documented in wound healing1 and in treatment of burns and radiation effects 2. It has been recommended for prescription for PID but there is not much data in literature regarding the efficacy in PID. So we conducted a trial to find efficacy of placentrex in comparision with azithromycin for the treatment of PID.

Site of infections associated with human papillomavirus.

Human papillomavirus (HPV) is the most clinically common sexually transmitted infection due to its carcinogenic power and the high number of lesions that it causes at different sites of the human body. Genital tract organs are the most common sites where the virus can be found, but by increasing the sensitivity of diagnostic technique, it is possible to identify viral presence in different regions of the body such as the stomach, the lung, and the urinary tract. These findings break with the traditional HPV skin/genital tropic profile and demonstrate that the virus is capable of infecting a wide variety of cells, tissues, and organs or can, at least, survive in these areas. The widespread presence of the HPV in the human body, often in latent form, led us to consider the hypothesis that HPV latency may be associated with no disease. This observation raises further questions about the possibility of the virus not causing disease in specific sites of the human body, but rather, behaving like a commensal/opportunistic microorganism.

Spectrum of histopathological lesions in the fallopian tubes

Background: Fallopian tubes are common surgical specimen in the pathology laboratory; still there is a lack of data to describe the frequency of various histological fi ndings. The aim and objectives of this study was to describe the various histopathological fi ndings of fallopian tubes. Materials and Methods: Two thousand fi ve hundred and seventy fi ve cases where fallopian tubes were removed either separately or along with other female genital tract organs were studied retrospectively and their histopathological fi ndings documented. Results: Ectopic pregnancy comprised maximum number of cases closely followed by salpingitis. Primary neoplastic lesions were rare as compared to secondary malignancies. Serial sections of fallopian tube and sections from representative areas are essential for a pathologist so that the diagnosis of these pathological entities is not missed. Conclusion: Though the fallopian tubes remain unremarkable in majority of the surgical pathological specimens, it must be subjected for histopathological examination to demonstrate the pathological lesions. Journal of Pathology of Nepal (2013) Vol. 3, No.1, Issue 5, 356-360 DOI: http://dx.doi.org/10.3126/jpn.v3i5.7858

Impact of Short-Term HAART Initiated during the Chronic Stage or Shortly Post-Exposure on SIV Infection of Male Genital Organs

BackgroundThe male genital tract is suspected to constitute a viral sanctuary as persistent HIV shedding is found in the semen of a subset of HIV-infected men receiving effective antiretroviral therapy (HAART). The origin of this persistent shedding is currently unknown. Phylogenetic studies indicated that HIV in semen from untreated men arises from local sources and/or passive diffusion from the blood. We previously demonstrated in human and macaque low levels and localized infection of several semen-producing organs by HIV/SIV. Using a macaque model, this study investigates the impact of short term HAART (2–4 weeks) initiated either during the asymptomatic chronic stage or 4 h post-intravenous inoculation of SIVmac251 on the infection of male genital organs.Methodology/Principal FindingsShort term HAART during the chronic stage decreased blood viral load. No major impact of HAART was observed on SIV DNA levels in male genital organs using a sensitive nested PCR assay. Using in situ hybridization, SIV RNA+ cells were detected in all male genital tract organs from untreated and treated animals with undetectable blood viral load following HAART. Infected CD68+ myeloid cells and CD3+ T lymphocytes were detected pre- and post-HAART. In contrast, short term HAART initiated 4 h post-SIV exposure led to a drastic decrease of the male genital tissues infection, although it failed to prevent systemic infection. In both cases, HAART tended to decrease the number of CD3+ T cells in the male organs.ConclusionsOur results indicate that the established infection of male genital organs is not greatly impacted by short term HAART, whereas the same treatment during pre-acute phase of the infection efficiently impairs viral dissemination to the male genital tract. Further investigations are now needed to determine whether infection of male genital organs is responsible for long term persistent HIV shedding in semen despite HAART.

Male Rat Genital Tract Infection With Chlamydia Muridarum has No Significant Consequence on Male Fertility

Chlamydia trachomatis infection of the male genital tract was proposed to alter male fertility. We studied the putative consequences of chlamydial male genital tract infection on semen quality and male fertility in an experimental rat model of infection. We used 36 male and 40 female Wistar rats. Male genital infection was created by inoculating Chlamydia muridarum in the meatal urethra. The presence of C. muridarum was evaluated by polymerase chain reaction in semen and male genital tract organs early (15 days) and late (80 days) after infection. Sperm quality parameters were assayed in seminal and epididymal sperm from sham infected and infected rats. Mating studies with sexually mature females were performed and fertility parameters were assayed, including potency, fecundity and fertility indexes, fetal size, and pre-implantation and post-implantation embryo loss. Male rats showed ascending, disseminated infection 15 days after infection. Bacteria persisted in the prostate and seminal vesicles 80 days after infection. C. muridarum was detected in semen in most rats regardless of acute or chronic infection. Seminal or epididymal sperm quality did not differ in infected and sham infected rats 15 or 80 days after infection. Sperm apoptosis was also minimal in infected rats. No differences were observed in fertility parameters between infected and sham infected rats. C. muridarum infects the rat male genital tract and persists mainly in the prostate. Although C. muridarum was detected in semen during acute and chronic infection, no alterations in sperm quality were observed. C. muridarum infection does not impair male fertility.

Le tractus génital masculin

Despite semen being the main vector of human immunodeficiency virus (HIV) dissemination worldwide, the origin of the virus in this bodily fluid remains unknown. Of particular significance is the persistence of virus release in the semen of a subset of HIV-infected men under antiretroviral therapy, who otherwise show an undetectable blood viral load. It is therefore considered critical to identify the sources of virus shedding in semen for the more efficient control of HIV transmission. Our recent findings indicate HIV infection of several semen-producing organs, including the testis (which represents a pharmacological sanctuary for several antiretroviral drugs). This reinforces phylogenetic observations suggesting that the free viral particles and infected cells contaminating semen are produced within the male genital tract. The fact that HIV replicates within the male genital organs raises several questions: Is one or several of the male genital tract organs responsible for the persistence of HIV in semen despite efficient antiviral therapies? What is the nature of HIV interactions with spermatozoa and testicular germ cells? Recent results established that semen from HIV negative men modifies HIV infectivity: does the seminal fluid from HIV+ men enhance or inhibit the efficiency of HIV sexual transmission?

Precursors of endometrial and ovarian carcinoma

This review discusses precursor lesions of endometrial and ovarian carcinoma with an emphasis on the unique molecular alterations that have led to the development of binary classification schemes for tumors of both the endometrium and ovary. While such a system is well established for endometrial carcinoma, only recently has a binary classification scheme been proposed for ovarian carcinoma. For both, the morphologic and molecular genetic-defining characteristics of their respective precursor lesions are described in detail. Furthermore, similarities and differences of the precursor lesions of specific tumors of these two genital tract organs are also addressed with a brief discussion of the clinical implications of their diagnosis.

Mixoid leiomyoma of the vagina: Case report with emphasis to diagnostic challenges

Leiomyoma is the most common benign mesenchymal tumour of the vagina in adult women,1 but no case of myxoid variant has been reported at this site. A 27-year-old nulliparous woman was admitted to hospital for dyspareunia, pressure symptoms on the urinary tract, vaginal pain and prolonged vaginal discharge. By vaginal exploration, a soft mass was palpated in the anterior wall vaginal measuring 7 × 6 cm. The magnetic resonance images revealed a vaginal tumour arising from the anterior vaginal wall (Fig. 1a,b). Enucleation of the vaginal tumour using a transvaginal approach was performed. (a) Sagittal T2-weighted magnetic resonance images show an inhomogeneous voluminous mass that displaced anteriorly the bladder (arrow). (b) Sagittal T2-weighted magnetic resonance images show an inhomogeneous voluminous mass that displaced cranially the uterus (head arrow). The vagina is dilated and show high signal intensity (*). (c–d) Histological pattern of mixoid leiomyoma: abundant amorphous mixoid material was present between the smooth muscle cells. (c) Haematoxylin and eosin (H&E) σταινινγ, ×200; (d) H&E staining, ×100. The mass was a well-encapsulated solid tumour measuring 8.5 × 7.5 × 6.5 cm with a smooth, pink surface. The cut surface was yellow and soft with a whorled or slightly nodular pattern and focal grey gelatinous areas. On microscopic examination, the majority of the tumour was hypocellular with delicate spindle cells dispersed in an amorphous, pale blue matrix (Fig. 1c). The matrix was positive for Alcian blue and colloidal iron stainings and was faintly positive for mucicarmine staining. Focal areas resembling typical leiomyoma were present. Nuclear atypia was absent, and the highest mitotic count was 1MF/10 HPF. The tumour cells showed strong positivity for muscle specific actin and focally for desmin. Fourteen months after the surgical removal, she was asymptomatic. Vaginal leiomyomas vary in size up to 5 cm, and sometimes may simulate malignancies (large size, unusual subtype, degenerative changes). Microscopically vaginal leiomyomas resemble those of the genital tract organs and may display bizarre,2 epithelioid and clear cell patterns.3 Since the first report by Denys de Leyden in 1773, approximately 300 cases have been reported.4 The criteria used for smooth-muscle tumours of the uterine corpus appear to be organ-specific and cannot be applied to counterpart arising elsewhere in the female genital tract. In evaluating vaginal smooth muscle tumours, we apply the criteria of malignancy used by Tavassoli and Norris3: presence of moderate to marked atypia and five or more mitotic figures per 10 high-power fields. Myxoid change may be seen in both benign and malignant smooth muscle tumours. This change has achieved notoriety in the uterus because some myxoid leiomyosarcomas have little nuclear atypia and a low mitotic rate making evaluation of borders crucial for placement in either a benign or a malignant category. In our case the tumour was well circumscribed, with no cytological atypia and a low mitotic rate. The diagnosis of benignancy is confirmed by follow up. After 14 months of surgical removal, the patient is free of disease. In the diagnosis of myxoid leiomyoma another diagnostic challenge is found when the myxoid degeneration is extensive. In this instance it may be difficult to identify the smooth nature of the tumour. A desmin or actins staining may be helpful in this situation. In our case the positivity of actin was diffusely found, although extensive mixoid areas were present. After a review of the literature, we shall consider that this is the probably first case report of myxoid leiomyoma of the vagina.

Susceptibility of Human Testis to Human Immunodeficiency Virus-1 Infection in Situ and in Vitro

Semen represents the main vector for human immunodeficiency virus (HIV) dissemination worldwide and has been shown to harbor replication-competent virus despite otherwise effective highly active anti-retroviral therapy, which achieves undetectable viral load in plasma. Despite this, the origin of seminal HIV particles remains unclear, as does the question of whether the male genital tract organs contribute virus to semen. Here we investigated the presence of HIV receptors within the human testis using immunohistochemistry and quantitative real-time polymerase chain reaction. We also analyzed the infectivity of a dual tropic HIV-1 strain in an organotypic culture, as well as the impact of viral exposure on testosterone production. Our study establishes that CXCR4+, CCR5+, CD4+, and DC-SIGN+ cells are present within the interstitial tissue of human testis and that these molecules persist throughout our organotypic culture. Our data also reveal that the human testis is permissive to HIV-1 and supports productive infection, leaving testosterone production apparently unaffected. Infected cells appeared to be testicular macrophages located within the interstitial tissue. That the testis itself represents a potential source of virus in semen could play a role in preventing viral eradication from semen because this organ constitutes a pharmacological sanctuary for many current antiretrovirals.

Surfactant protein A and D in the reproductive tract of stallion

The presence of surface-active material in the lung alveolus has been known for several decades as being essential for normal lung function. The host defense and controlling inflammatory processes of the lung are the major functions of SP-A and SP-D. SP-A and SP-D were originally demonstrated in alveolar type II cells, but recent studies have shown extrapulmonary expression of SP-A and SP-D indicating systemic roles of these proteins. Present study describes the presence of SP-A and SP-D in the stallion genital tract, prepuce, prostate, testis, and seminal vesicle using Western blotting and immunohistochemistry. This paper presents the first evidence for the existence of SP-A and SP-D glycoproteins in the stallion genital tract. We examined genital system organs and tissues from stallion and were able to show that surfactant protein A and D reactive with surfactant-specific antibodies were present in the stallion genital tract tissues and organs. On the basis of results, it can be postulated that surfactant proteins in the stallion reproductive tract contribute to the immune surveillance and to active barrier defense mechanism.

Metastatic extragenital neoplasms to the uterus: a clinicopathologic study of four cases

The aim of this study was to elucidate the clinicopathologic features, the differential diagnostic problems, and the prognostic consequences of patients with metastatic extragenital malignancies to uterus. The patients with metastatic extragenital malignancies to the uterus were evaluated. We considered the metastases in non-genital tract organs at diagnosis of primary neoplasm, the distribution of the metastases in the uterus, and the presence of concomitant metastases in other genital and non-genital tract organs. There were four cases of metastatic extragenital malignancies to the uterus. The breast was the most frequent primary site (two cases: 50%). The other two primary tumors were adenocarcinoma of the cecum and malignant melanoma of the skin. The diagnosis was facilitated by clinical history, revealing the previous primary neoplasm, and by specific immunohistochemical study. Almost all the patients died from disseminated disease. Thus, the prognosis of metastatic extragenital malignancies to the uterus alone or simultaneously to the uterus and other organs of the genital tract is poor. Thus, the metastases to the uterus and to other organs of the genital tract can be considered a preterminal event.

Metastatic extragenital neoplasms to the uterus: a clinicopathologic study of four cases

The aim of this study was to elucidate the clinicopathologic features, the differential diagnostic problems, and the prognostic consequences of patients with metastatic extragenital malignancies to uterus. The patients with metastatic extragenital malignancies to the uterus were evaluated. We considered the metastases in non–genital tract organs at diagnosis of primary neoplasm, the distribution of the metastases in the uterus, and the presence of concomitant metastases in other genital and non–genital tract organs. There were four cases of metastatic extragenital malignancies to the uterus. The breast was the most frequent primary site (two cases: 50%). The other two primary tumors were adenocarcinoma of the cecum and malignant melanoma of the skin. The diagnosis was facilitated by clinical history, revealing the previous primary neoplasm, and by specific immunohistochemical study. Almost all the patients died from disseminated disease. Thus, the prognosis of metastatic extragenital malignancies to the uterus alone or simultaneously to the uterus and other organs of the genital tract is poor. Thus, the metastases to the uterus and to other organs of the genital tract can be considered a preterminal event.

Epithelial cells in the oviduct and vagina and steroid-synthesizing cells in the rabbit ovary express AhR and ARNT.

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor. Beside exogenous ligands, an increasing list of endogenous ligands has recently been described. The AhR and its dimerization partner AhR nuclear translocator (ARNT) were found in embryos, fetuses and in genital tract tissue. Its role in reproduction and fertility is not known. In the current study, AhR and ARNT expression and co-localization were studied immunohistochemicaly during the pre-implantation period in various genital tract organs (ovary, oviduct, vagina) of the rabbit. In the ovary, the AhR was expressed in the steroid-secreting interstitial cells, in follicular and granulosa cells, and in lutein cells. The receptor was localized in the cytoplasm. A cytoplasmic localization was also found in the oviduct epithelium with a diffuse cytoplasmic staining in the ampulla and a localized cytoplasmic localization in the isthmus. In the vagina, AhR localization changed from cytoplasmic in the non-pregnant animal to nuclear staining in the basal layer of the vaginal epithelium on day 6 of pregnancy. The ARNT protein was found in all AhR expressing cells except for oocytes within primordial follicles. Its localization was in the cytoplasm and/or nuclei. Therefore, the full complement for AhR/ARNT transcriptional activity was found in the studied organs. AhR expression showed stage-specific changes in both the uterus (Hasan and Fischer 2001) and the vagina during the pre-implantation period, while the ARNT protein exhibited no change in expression during this period. In summary, these findings indicate a functional AhR/ARNT complex in the rabbit genital tract epithelia. Its precise role and activation mechanism in reproductive tissue is not clear. It is supposed, however, that this complex may be involved in both hormone production and hormone-induced cellular changes during early pregnancy of the rabbit.