Nature of "basal" and "reserve" cells in oviductal and cervical epithelium in man

Terminological discrepancies and novelties in the histological description of the female genital system: proposed amendments for clinical-translational anatomy

Histological terminology of the female genital organs is currently a part of the internationally accepted nomenclature Terminologia Histologica (TH), the latest edition of which dates back to 2008. Many new discoveries have been documented within 16 years since then, and many discrepancies have been found. This paper aims to revise the terminology from clinical and educational perspectives comprehensively. The authors thoroughly searched the current edition of "Terminologia Histologica: International Terms for Human Cytology and Histology," focusing on missing and controversial terms in the chapter Female genital system. The authors identified six controversial and ambiguous terms and four missing important histological terms. The authors also discussed the addition of less used eponymic terms in the histological description of female genital organs like Hamperl cells, Popescu cells, Kroemer lacunae, Balbiani bodies, Call-Exner bodies, membrane of Slavianski, nabothian cysts, or anogenital sweat glands of van der Putte. We expect the second and revised edition of the TH to be published soon and hope that the Federative International Program on Anatomical Terminology will approve and incorporate all these propositions and suggestions. We also strongly recommend using the official internationally accepted Latin and English histological nomenclature-the TH, either in oral or written form, both in theoretical and clinical medicine.

Cellular heterogeneity of human fallopian tubes in normal and hydrosalpinx disease states identified using scRNA-seq

Fallopian tube (FT) homeostasis requires dynamic regulation of heterogeneous cell populations and is disrupted in infertility and ovarian cancer. Here, we applied single-cell RNA-seq to profile 59,738 FT cells from four healthy, pre-menopausal subjects. The resulting cell atlas contains 12 major cell types representing epithelial, stromal, and immune compartments. Re-clustering of epithelial cells identified four ciliated and six non-ciliated secretory epithelial subtypes, two of which represent potential progenitor pools: one leading to mature secretory cells and the other contributing to either ciliated cells or one of the stromal cell types. To understand how FT cell numbers and states change in a disease state, we analyzed 17,798 cells from two hydrosalpinx samples and observed shifts in epithelial and stromal populations and cell-type-specific changes in extracellular matrix and TGF-β signaling; this underscores fibrosis pathophysiology. This resource is expected to facilitate future studies aimed at expanding understanding of fallopian tube homeostasis in normal development and disease.

Organoids of the female reproductive tract

Healthy functioning of the female reproductive tract (FRT) depends on balanced and dynamic regulation by hormones during the menstrual cycle, pregnancy and childbirth. The mucosal epithelial lining of different regions of the FRT-ovaries, fallopian tubes, uterus, cervix and vagina-facilitates the selective transport of gametes and successful transfer of the zygote to the uterus where it implants and pregnancy takes place. It also prevents pathogen entry. Recent developments in three-dimensional (3D) organoid systems from the FRT now provide crucial experimental models that recapitulate the cellular heterogeneity and physiological, anatomical and functional properties of the organ in vitro. In this review, we summarise the state of the art on organoids generated from different regions of the FRT. We discuss the potential applications of these powerful in vitro models to study normal physiology, fertility, infections, diseases, drug discovery and personalised medicine.

The Repertoire of Serous Ovarian Cancer Non-genetic Heterogeneity Revealed by Single-Cell Sequencing of Normal Fallopian Tube Epithelial Cells

The inter-differentiation between cell states promotes cancer cell survival under stress and fosters non-genetic heterogeneity (NGH). NGH is, therefore, a surrogate of tumor resilience but its quantification is confounded by genetic heterogeneity. Here we show that NGH in serous ovarian cancer (SOC) can be accurately measured when informed by the molecular signatures of the normal fallopian tube epithelium (FTE) cells, the cells of origin of SOC. Surveying the transcriptomes of ∼6,000 FTE cells, predominantly from non-ovarian cancer patients, identified 6 FTE subtypes. We used subtype signatures to deconvolute SOC expression data and found substantial intra-tumor NGH. Importantly, NGH-based stratification of ∼1,700 tumors robustly correlated with survival. Our findings lay the foundation for accurate prognostic and therapeutic stratification of SOC.

Aberrantly elevated Bmi1 promotes cervical cancer tumorigenicity and tumor sphere formation via enhanced transcriptional regulation of Sox2 genes

The exact molecular mechanisms underlying cervical tumorigenesis are poorly understood. Polycomb complex protein Bmi1 (Bmi1) is involved in the malignant transformation and biological aggressiveness of several human carcinomas. Therefore, the present study assessed the expression of Bmi1 protein in human cervical cancer tissues and examined the mechanisms involved in cervical carcinogenesis. The expression of Bmi1 protein was examined by immunohistochemistry in cervical carcinoma tissues (n=71), high-grade squamous intraepithelial lesions (n=41) and normal cervical tissues (n=47). Expression of Bmi1 protein gradually increased across samples from the normal cervix (1/47; 2.12%), high-grade squamous intraepithelial lesions (5/42; 16.13%) and cervical carcinomas (31/71; 43.66%; P<0.05). Additionally, Bmi1 protein expression was associated with tumor histopathological grade. The effects of Bmi1 silencing and overexpression on tumor sphere formation and the tumorigenicity of cervical cancer cells were investigated. Overexpression of Bmi1 resulted in significantly attenuated tumor formation and tumor sphere formation. Consistently, Bmi1 silencing significantly inhibited tumor formation and tumor sphere formation. Furthermore, Bmi1 upregulated the expression of Sox2, and the dual-luciferase reporter assay and chromatin immunoprecipitation showed that Bmi1 transactivated Sox2 by binding to the two E-box motifs in the Sox2 promoter. In conclusion, aberrantly elevated Bmi1 promotes cervical cancer tumorigenicity and tumor sphere formation via enhanced transcriptional regulation of Sox2 genes as a potential oncogenic factor that participates in the carcinogenesis of cervical carcinomas.

In vivo genetic cell lineage tracing reveals that oviductal secretory cells self-renew and give rise to ciliated cells

The epithelial lining of the fallopian tube is vital for fertility, providing nutrition to gametes and facilitating their transport. It is composed of two major cell types: secretory cells and ciliated cells. Interestingly, human ovarian cancer precursor lesions primarily consist of secretory cells. It is unclear why secretory cells are the dominant cell type in these lesions. Additionally, the underlying mechanisms governing fallopian tube epithelial homoeostasis are unknown. In the present study, we showed that across the different developmental stages of mouse oviduct, secretory cells are the most frequently dividing cells of the oviductal epithelium. In vivo genetic cell lineage tracing showed that secretory cells not only self-renew, but also give rise to ciliated cells. Analysis of a Wnt reporter mouse model and various Wnt target genes showed that the Wnt signaling pathway is involved in oviductal epithelial homoeostasis. By developing two triple-transgenic mouse models, we showed that Wnt/β-catenin signaling is essential for self-renewal as well as the differentiation of secretory cells. In summary, our results provide mechanistic insight into oviductal epithelial homoeostasis.

The HPV16 E7 oncoprotein increases the expression of Oct3/4 and stemness-related genes and augments cell self-renewal

Oct3/4 is a transcription factor involved in maintenance of the pluripotency and self-renewal of stem cells. The E7 oncoprotein and 17β-estradiol (E₂) are key factors in cervical carcinogenesis. In the present study, we aimed to investigate the effect of the HPV16 E7 oncoprotein and E₂ on the expression pattern of Oct3/4, Sox2, Nanog and Fgf4. We also determined whether the E7 oncoprotein is associated with cell self-renewal. The results showed that Oct3/4, Sox2, Nanog and Fgf4 were upregulated by the E7 oncoprotein in vivo and in vitro and implicate E₂ in the upregulation of these factors in vivo. We also demonstrated that E7 is involved in cell self-renewal, suggesting that the HPV16 E7 oncoprotein upregulates Oct3/4, Sox2, Nanog and Fgf4 expression to maintain the self-renewal capacity of cancer stem cells.

Hiwi facilitates chemoresistance as a cancer stem cell marker in cervical cancer

Hiwi, also named PiwiL1, is a human homologue of the Piwi family which is associated with stem cells and is overexpressed in several types of cancers. In the present study, we aimed to investigate the role of Hiwi in cervical carcinogenesis. Immunochemical analysis showed a significantly higher frequency of Hiwi staining in high-grade squamous intraepithelial lesions (HSILs) and cervical cancer tissues when comparing with the frequency in normal cervices. Particularly, Hiwi staining was restricted to basal cells of the normal cervix and was associated with the progression of cervical cancer and chemotherapy resistance. We further found that ectopic Hiwi increased the chemical resistance in SiHa cells, and silencing of Hiwi in HeLa cells decreased the cell viability. In addition, as a cancer stem cell marker, Hiwi promoted the tumorsphere formation in vitro and tumorigenicity in vivo and elevated the expression of several stem cell self-renewal-associated transcription factors, in spite of inhibited the proliferation. These results suggest that Hiwi may participate in the carcinogenesis of cervical cancer and may be a potential therapeutic target molecule for cervical cancers.

Stem-like epithelial cells are concentrated in the distal end of the fallopian tube: a site for injury and serous cancer initiation

The reproductive role of the fallopian tube is to transport the sperm and egg. The tube is positioned to act as a bridge between the ovary where the egg is released and the uterus where implantation occurs. Throughout reproductive years, the fallopian tube epithelium undergoes repetitive damage and regeneration. Although a reservoir of adult epithelial stem cells must exist to replenish damaged cells, they remain unidentified. Here, we report isolation of a subset of basally located human fallopian tube epithelia (FTE) that lack markers of ciliated (β-tubulin; TUBB4) or secretory (PAX8) differentiated cells. These undifferentiated cells expressed cell surface antigens: epithelial cell adhesion molecule, CD44, and integrin α 6. This FTE subpopulation was fivefold enriched for cells capable of clonal growth and self-renewal suggesting that they contain the FTE stem-like cells (FTESCs). A twofold enrichment of the FTESC was found in the distal compared to the proximal end of the tube. The distal fimbriated end of the fallopian tube is a well-characterized locus for initiation of serous carcinomas. An expansion of the cells expressing markers of FTESC was detected in tubal intraepithelial carcinomas and in fallopian tubes from patients with invasive serous cancer. These findings suggest that FTESC may play a role in the initiation of serous tumors. Characterization of these stem-like cells will provide new insight into how the FTE regenerate, respond to injury, and may initiate cancer.

Coexpression of B-lymphoma Moloney murine leukemia virus insertion region-1 and sex-determining region of Y chromosome-related high mobility group box-2 in cervical carcinogenesis

B-lymphoma Moloney murine leukemia virus insertion region-1 is an oncogene in various human tumors, and overexpression correlates with a poor clinical outcome. Sex-determining region of Y chromosome-related high mobility group box-2, coding for a critical transcription factor determining the fate of stem cells, was recently identified as an oncogene in human cervical carcinoma and other tumors. However, the roles of B-lymphoma Moloney murine leukemia virus insertion region-1 and sex-determining region of Y chromosome-related high mobility group box-2 in the pathogenesis of cervical carcinoma are poorly understood. We initially observed a more pronounced increase in B-lymphoma Moloney murine leukemia virus insertion region-1 protein expression in primary cervical carcinoma than in normal cervical tissues, and B-lymphoma Moloney murine leukemia virus insertion region-1 protein expression correlated significantly with sex-determining region of Y chromosome-related high mobility group box-2 protein expression, as seen by Western blotting (r = 0.75; P < .01). Furthermore, B-lymphoma Moloney murine leukemia virus insertion region-1 and sex-determining region of Y chromosome-related high mobility group box-2 both had higher expression in cervical carcinoma than in normal cervical tissue, and the amounts correlated with pathologic grade. Immunofluorescence analysis showed that B-lymphoma Moloney murine leukemia virus insertion region-1 colocalized in the nucleus with sex-determining region of Y chromosome-related high mobility group box-2 in both normal cervical tissue and cervical carcinoma. From the cervical carcinoma cell line SiHa, we isolated 2 clones, B-lymphoma Moloney murine leukemia virus insertion region-1(+)/sex-determining region of Y chromosome-related high mobility group box-2(+) (SiHa-3) and B-lymphoma Moloney murine leukemia virus insertion region-1(-)/sex-determining region of Y chromosome-related high mobility group box-2(-) (SiHa-2). The SiHa-3 cells grew better in vitro and formed tumors more readily in vivo than did SiHa-2. Knockout of sex-determining region of Y chromosome-related high mobility group box-2 inhibited cell growth in vitro with a block at G1/S. In contrast, knockout of B-lymphoma Moloney murine leukemia virus insertion region-1 did not affect either cell growth in vitro or the cell cycle. Interference with either B-lymphoma Moloney murine leukemia virus insertion region-1 or sex-determining region of Y chromosome-related high mobility group box-2 in SiHa-3 significantly inhibited tumorigenesis (P < .05). Coexpression of B-lymphoma Moloney murine leukemia virus insertion region-1 and sex-determining region of Y chromosome-related high mobility group box-2 may promote cervical carcinogenesis.

Expression of Sox2 in human cervical carcinogenesis

Sox2 is a key transcription factor for embryonic development and plays a critical role in determining the fate of stem cells. Recently, Sox2 has been detected in several human tumors, indicating a potential function in tumorigenesis. We initially reported remarkably increased nuclear Sox2 staining in cervical carcinomas compared with normal cervix (P < .05). Furthermore, Sox2 staining was detected in most tumorsphere cells isolated from fresh cervical cancer tissues but not among the differentiated tumorsphere cells. When Sox2 was stably expressed in cervical cancer cells (SiHa and HeLa), Sox2-overexpressing cells had increased proliferation, clonogenicity, and tumorigenicity in vitro and in vivo than control cells. These results suggest that Sox2 may participate in carcinogenesis of cervical carcinomas and may be a potential therapeutic target molecule for cervical cancers.

Characterisation of lymphocyte subsets in the equine oviduct

REASONS FOR PERFORMING STUDY

The equine oviduct is the site of fertilisation and location of embryonic development during the first 5 or 6 days. It therefore has an important influence on mare fertility. Although histopathological changes have been described previously, there is limited information regarding lymphocyte subtypes present in the mucosa of the normal equine oviduct.

OBJECTIVES

To characterise the distribution of CD3+, CD4+, CD8+ and B lymphocytes in the equine oviduct from inseminated mares during oestrus and dioestrus, and from noninseminated mares during the immediate post ovulatory period.

METHODS

Oviductal tissues were collected from noninseminated mares at oestrus (> 30 mm follicle, n = 4), at Day 1 post ovulation (n = 3) and at dioestrus (Day 7 post ovulation; n = 4). Oviducts were also collected from inseminated mares at Days 1, 2, and 3 post ovulation (n = 4 for each period). Cross-sections of tissues from the ampullar-isthmic junction from each oviduct were snap frozen and cryostat sections stained by the immunoperoxidase technique with monoclonal antibodies directed against equine lymphocyte surface markers for B cells as well as CD3+, CD4+ and CD8+ cells.

RESULTS

In all oviductal sections examined, B cells were rare whereas T cells were relatively abundant. The predominant cell type found was the CD8+ phenotype, with a lesser number of CD4+ cells. Among mares, individual variation was large; therefore, although breeding status and stage of oestrous cycle appeared to alter lymphocyte populations, these differences were not significant.

CONCLUSIONS AND POTENTIAL RELEVANCE

A population of CD3+, CD4+ and CD8+ cells exists within the mucosal region of the equine oviduct. The density of these cells is similar to that described in the human oviduct. Their function is not currently known, but they may be involved with modulation of the maternal response to the presence of spermatozoa or the early conceptus within the equine oviduct. As our capacity to differentiate these cell types improves, along with the ability to identify the specific cytokines they produce, their functional significance will become more apparent.

The influence of pre- and post-ovulatory insemination and early pregnancy on the infiltration by cells of the immune system in the sow oviduct

The aim of this study was to investigate the influence of pre- and post-ovulatory insemination and early pregnancy on the distribution of immune cells in the oviduct. Eighteen sows were pre-ovulatory and sixteen sows were post-ovulatory inseminated and slaughtered at different times, 5-6 h after insemination, 20-25 h and approximately 70 h after ovulation, day 11 and day 19. Immediately after slaughter, oviductal samples of three different segments (isthmus, ampulla and infundibulum) were fixed, embedded in plastic resin and stained with toluidine blue or cryofixed and stored in a freezer at -70 degrees C until analysed by immunohistochemistry (pre-ovulatory inseminated sows) with an avidin-biotin peroxidase method. Quantitative and qualitative examinations of oviductal epithelium and subepithelial connective tissue were performed by light microscopy. After pre- or post-ovulatory insemination, neutrophils were not observed in the oviductal epithelium from any of the segments or groups. The numbers of intraepithelial lymphocytes of all sows as well as CD2- and CD3-positive cells of the pre-ovulatory inseminated sows were higher in the infundibulum than in the other segments (p < or = 0.001). In the subepithelial connective tissue of the pre-ovulatory inseminated sows, significantly higher numbers of lymphocytes (p < or = 0.001) and plasma cells (p < or = 0.001) were found in infundibulum than in isthmus. Neutrophils were found mainly in infundibulum, the number approximately 40 h after pre-ovulatory insemination was significantly higher (p < or = 0.05) than in the other groups and segments. Significantly higher numbers of CD2 than CD3-positive cells were found for all groups and segments. In the subepithelial connective tissue of post-ovulatory inseminated sows, the numbers of lymphocytes was higher (p < or = 0.001) at day 19 than up to 50 h after insemination and lower (p < or = 0.001) in isthmus than in ampulla and infundibulum. Neutrophils were found in infundibulum in almost all groups and the number was significantly higher (p < or = 0.05) in the infundibulum up to 50 h after insemination than in other segments. In the oviductal epithelium, no influence of insemination was found on the presence of phagocytes, i.e. neutrophils and macrophages, but on lymphocytes. In the infundibular connective tissue, pre-ovulatory insemination had an effect on neutrophil distribution, indicating an active immune response to insemination in the upper segment. Post-ovulatory insemination changed the oviductal immune cell pattern.

The sow endosalpinx at different stages of the oestrous cycle and at anoestrus: studies on morphological changes and infiltration by cells of the immune system

The aim of this study was to investigate the morphological changes of the sow endosalpinx and the distribution of leukocytes throughout the oestrous cycle and at anoestrus. Nineteen crossbred sows (Swedish Landrace x Swedish Yorkshire) at late dioestrus (three), prooestrus (three), oestrus (three), early dioestrus (three), dioestrus (three) and anoestrus (four) were used. Oviductal samples from three different parts (isthmus, ampulla and infundibulum), taken immediately after slaughter, were fixed, embedded in plastic resin and stained with toluidine blue or stored in a freezer at -70 degrees C until analysed by immunohistochemistry (prooestrus and anoestrus) with an avidin-biotin peroxidase method. Quantitative and qualitative examinations of oviductal epithelium and subepithelial connective tissue were performed by light microscopy. During all stages, a lower degree of morphological changes (pseudostratification, mitosis and secretory granules) was found in the isthmus compared with ampulla and infundibulum. In ampulla and infundibulum, pseudostratification, mitotic activity and secretory granules of the epithelium were high at prooestrus/oestrus. Cytoplasmic protrusions of epithelial cells with some extruded nuclei were prominent in ampulla and infundibulum at all stages except for oestrus and early dioestrus. Lymphocytes as well as CD2- and CD3-positive cells were the predominant immune cells in the epithelial layer. The numbers of lymphocytes and CD3-positive cells did not differ among segments and stages. Numbers of CD2-positive cells did not differ between prooestrus and anoestrus while the numbers were significantly higher in the infundibulum than in ampulla and isthmus. Neutrophils were only occasionally found and mainly in the infundibulum. In the subepithelial connective tissue layer, the two most commonly observed immune cell types were lymphocytes and plasma cells. The numbers of lymphocytes as well as CD2- and CD3-positive cells was lower in isthmus than in the other segments (p < or = 0.001). Higher numbers of plasma cells (p < or = 0.001) were found in infundibulum than in ampulla and isthmus. The numbers of lymphocytes and plasma cells were not significantly different between stages of the oestrous cycle. However, the number of neutrophils differed and were highest at prooestrus in ampulla and infundibulum. The numbers of CD2-, CD3- and CD79-positive cells did not differ between prooestrus and anoestrus whereas for CD14- and SWC3-positive cells, the numbers were higher at prooestrus (p < or = 0.05) than at anoestrus. In the oviduct, the morphology differed in ampulla and infundibulum with oestrous cycle stages, which indicates an effect by ovarian steroid hormones. The immune cell infiltration was less influenced by cyclic changes. However, the immune cell infiltration (in the connective tissue) in the upper part, especially infundibulum, differed significantly from the one in the lower part, isthmus, indicating different immune functions within various parts of the oviduct.

The human leucocyte antigen (HLA) DR expression and the distribution of T-lymphocytes in the fimbriae of the normal fallopian tube and during pelvic adhesion disease

PROBLEM

Systematically to investigate the expression of human leucocyte antigen (HLA) DR on the columnar epithelium and the content of T-lymphocytes in the fimbriae specimens of the fallopian tube from healthy women and from women with infertility and pelvic adhesions.

METHOD

The staining of HLA-DR expression on the columnar epithelium was judged on a four-graded scale according to the distribution of HLA-DR expression. The amount and distribution of T-lymphocytes were registered.

RESULTS

The biopsies from normal fimbriae contained sparsely infiltrating T-lymphocytes. On the columnar epithelial cells a patchy HLA-DR expression was observed that was more widespread in preovulatory cases. In some biopsies from sactosalpinx, the HLA-DR expression was found completely to cover the columnar epithelial cells and was associated with a heavy infiltration of T-lymphocytes. CD4+ T-lymphocytes dominated in all but one adhesion biopsies.

CONCLUSION

The findings indicate an ongoing immunological activity in pelvic adhesions that might immunologically influence fertility.

Identification of lymphocyte subsets in the human fallopian tube

PROBLEM

Immunohistochemical investigations for the detection of lymphocyte subsets in the human oviduct have been performed. Knowledge about local immunity especially cell-mediated immunity, in the fallopian tube has been, up to now, limited. As an essential structure for the human reproduction process, the tubal mucous membrane is exposed to a variety of antigens.

METHOD

A total number of 20 tubal biopsies obtained from fertile women during gynecological operations like tubal ligations or hysterectomy were examined by the immunoperoxidase technique. Seven specimens were obtained during the proliferative phase, ten during the secretory phase and three during a caesarean section with tubal ligations.

RESULTS

It could be established that the presence of lymphocytes in the oviductal mucous membrane is physiological. These cells can be identified by their typical immunohistochemical patterns. There were no significant differences of the type and number of lymphocytes in the mucosa within the phases of menstrual cycle. The dominant cell types in the tubal mucosa were the CD3+ and CD8+ lymphocytes.

CONCLUSIONS

It can be suggested that the lymphocytes in the tubal mucosa may involved in the process of immune tolerance, which could realize the transport of sperms and blastocysts through the oviduct under normal conditions without activation of local immune mechanisms. The lymphoid tissue of the oviduct is a specialized form of mucosal-associated lymphoid tissue (MALT).

The ultrastructural changes of the mucosa of blocked fallopian tubes

The ultrastructure of the epithelium was studied in four blocked fallopian tubes which differed in the site of blockage and the degree of luminal distension. In all four specimens, there were large areas of the luminal surface which became barren and devoid of both the secretory and ciliated cells. Necrotic secretory cells and partially sloughed ciliated cells were observed in the remaining epithelium. Isolated patches of attenuated epithelium decorated with ciliated cells were sometimes found in the crypt of the mucosal folds. Results of this study suggest that pathological changes in the epithelium are common to tubes of both the terminal and cornual blockage.

Characterization of subcolumnar reserve cells and other epithelia of human uterine cervix. Demonstration of diverse cytokeratin polypeptides in reserve cells

We have analyzed the expression of cytokeratin polypeptides in subcolumnar reserve cells of the human uterine endocervical mucosa and the other epithelial cells using immunoperoxidase and immunofluorescence microscopy as well as by applying two-dimensional gel electrophoresis to microdissected cytoskeletal preparations. Endocervical columnar cells were uniformly positive for antibodies directed against the simple epithelium-type cytokeratins nos. 7, 8, 18, and 19, while a variable proportion of these cells was stained by an antibody against cytokeratin no. 4. Reserve cells were not only positive for cytokeratins nos. 8 (weakly and variably) and 19 but were also decorated by antibody KA 1, which reacts with cytokeratins present in stratified squamous epithelia. This last antibody selectively decorated reserve cells even when they were flat and inconspicuous. Antibody KA 1 uniformly stained the ectocervical squamous epithelium, the basal cells of which were also decorated by antibodies directed against cytokeratins nos. 8 (weakly and variably) and 19. Ectocervical suprabasal cells were positive, to a variable extent, for antibodies against cytokeratins nos. 4, 10/11, and 13. Gel electrophoresis revealed the presence of squamous-type cytokeratins nos. 5 and 17 in reserve cell-rich, but not in reserve cell-free, endocervical mucosa. We also analyzed the distribution pattern of these cells, as revealed by antibody KA 1, in the endocervical mucosa of 26 uteri. In all the specimens examined reserve cells were present, but their numbers exhibited considerable variation. In some cases these cells were confined to small islets localized deep within the cervical canal and lacked any continuity with the squamous epithelium. The expression of cytokeratins nos. 5 and 17 in reserve cells indicates that these cells have undergone a low level of squamous differentiation. The additional expression of cytokeratins nos. 8 and 19 in these cells points to a relationship with simple epithelial cells. The present data would seem to favor the view that reserve cells originate in situ from the columnar epithelium; however, this would imply an acquisition of new differentiation properties.

Leucocyte populations in ectopic tubal pregnancy

Leucocytes at the ectopic implantation site in 10 cases of early tubal pregnancy were characterised with a series of monoclonal antibodies using an indirect immunoperoxidase technique on cryostat sections. Most were HLA-DR positive macrophages, and there were a small number of mature T lymphocytes (UCHT1 and Dako-T1 positive cells). These results were compared with those reported in normal first trimester intrauterine pregnancies, and the contributions of the various leucocyte types to successful implantation at both the ectopic and intrauterine sites were assessed.