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Biomedical subjects

M J O'Brien

Publications and source records attributed to M J O'Brien.

At least 19 recordsLinked to original sources
PubMed2002

Prolapsing mucosal polyps: an underrecognized form of colonic polyp--a clinicopathological study of 15 cases.

OBJECTIVE: Prolapsing intestinal mucosa occurs in many forms throughout the GI tract. We describe 15 patients with polypoid masses in the sigmoid colon and histological features of mucosal prolapse. METHODS: Fifteen patients with colon polyps demonstrating endoscopic and histological features of mucosal prolapse were retrospectively identified from our database. RESULTS: Twelve patients presented with signs and symptoms that were nonspecific, but consistent with mucosal prolapse, such as occult or gross intestinal bleeding and lower abdominal pain. Three patients were asymptomatic. The polyps occurred in the sigmoid colon, usually in association with diverticular disease, and appeared more often in men. Endoscopically, the polyps appeared to be well-circumscribed, hyperemic masses that contrasted sharply with normal-appearing adjacent mucosa. Histological features include glandular crypt abnormalities, fibromuscular obliteration of the lamina propria, and thickened and splayed muscularis mucosa. CONCLUSIONS: Prolapsing mucosal polyps of the colon are histologically similar to other mucosal prolapsing conditions in the GI tract, such as the solitary rectal ulcer syndrome, inflammatory cloacogenic polyps, inflammatory "cap" polyps, and gastric antral vascular ectasia, and should therefore be designated as part of the "mucosal prolapse syndrome."

Adult↗
PubMed2001

Intercellular communication via connexin43 gap junctions is required for ovarian folliculogenesis in the mouse.

The ovarian follicle in mammals is a functional syncytium, with the oocyte being coupled with the surrounding cumulus granulosa cells, and the cumulus cells being coupled with each other and with the mural granulosa cells, via gap junctions. The gap junctions coupling granulosa cells in mature follicles contain several different connexins (gap junction channel proteins), including connexins 32, 43, and 45. Connexin43 immunoreactivity can be detected from the onset of folliculogenesis just after birth and persists through ovulation. In order to assess the importance of connexin43 gap junctions for postnatal folliculogenesis, we grafted ovaries from late gestation mouse fetuses or newborn pups lacking connexin43 (Gja1(-)/Gja1(-)) into the kidney capsules of adult females and allowed them to develop for up to 3 weeks (this was necessitated by the neonatal lethality caused by the mutation). By the end of the graft period, tertiary (antral) follicles had developed in grafted normal (wild-type or heterozygote) ovaries. Most follicles in Gja1(-)/Gja1(-) ovaries, however, failed to become multilaminar, with the severity of the effect depending on strain background. Dye transfer experiments indicated that intercellular coupling between granulosa cells is reduced, but not abolished, in the absence of connexin43, consistent with the presence of additional connexins. These results suggest that coupling between granulosa cells mediated specifically by connexin43 channels is required for continued follicular growth. Measurements of oocyte diameters revealed that oocyte growth in mutant follicles is retarded, but not arrested, despite the arrest of folliculogenesis. The mutant follicles are morphologically abnormal: the zona pellucida is poorly developed, the cytoplasm of both granulosa cells and oocytes is vacuolated, and cortical granules are absent from the oocytes. Correspondingly, the mutant oocytes obtained from 3-week grafts failed to undergo meiotic maturation and could not be fertilized, although half of the wild-type oocytes from 3-week grafted ovaries could be fertilized. We conclude that connexin43-containing gap junction channels are required for expansion of the granulosa cell population during the early stages of follicular development and that failure of the granulosa cell layers to develop properly has severe consequences for the oocyte.

Animals↗
PubMed2001

A surface plasmon resonance array biosensor based on spectroscopic imaging.

We have developed a multi-element transduction system which combines conventional SPR spectroscopy with one-dimensional SPR microscopy to create an effective platform for monitoring binding events on macro- or micro-patterned receptor arrays created on disposable sensor chips. This creates an effective platform for monitoring simultaneous binding events on each of the regions patterned with the receptors. This system has been specifically designed with commercially available components to allow relatively easy duplication. Furthermore, this system can use a proven, simple method to compensate for changes in the bulk index of refraction of the solution containing the analytes due to changes in temperature or solute concentration with simple modifications to the sensor chips alone. Preliminary results demonstrate how this system can be used to monitor several independent biospecific binding events simultaneously.

Biosensing Techniques↗
PubMed2000

A comparison of colonoscopy and double-contrast barium enema for surveillance after polypectomy. National Polyp Study Work Group.

BACKGROUND: After patients have undergone colonoscopic polypectomy, it is uncertain whether colonoscopic examination or a barium enema is the better method of surveillance. METHODS: As part of the National Polyp Study, we offered colonoscopic examination and double-contrast barium enema for surveillance to patients with newly diagnosed adenomatous polyps. Although barium enema was performed first, the endoscopist did not know the results. RESULTS: A total of 973 patients underwent one or more colonoscopic examinations for surveillance. In the case of 580 of these patients, we performed 862 paired colonoscopic examinations and barium-enema examinations that met the requirements of the protocol. The findings on barium enema were positive in 222 (26 percent) of the paired examinations, including 139 of the 392 colonoscopic examinations in which one or more polyps were detected (rate of detection, 35 percent; 95 percent confidence interval, 31 to 40 percent). The proportion of examinations in which adenomatous polyps were detected by barium enema colonoscopy was significantly related to the size of the adenomas (P=0.009); the rate was 32 percent for colonoscopic examinations in which the largest adenomas detected were 0.5 cm or less, 53 percent for those in which the largest adenomas detected were 0.6 to 1.0 cm, and 48 percent for those in which the largest adenomas detected exceeded 1.0 cm. Among the 139 paired examinations with positive results on barium enema and negative results on colonoscopic examination in the same location, 19 additional polyps, 12 of which were adenomas, were detected on colonoscopic reexamination. CONCLUSIONS: In patients who have undergone colonoscopic polypectomy, colonoscopic examination is a more effective method of surveillance than double-contrast barium enema.

Adenoma↗
PubMed2000

Conditions that affect acquisition of developmental competence by mouse oocytes in vitro: FSH, insulin, glucose and ascorbic acid.

The simplest unit required for the support of oocyte growth and development is the oocyte-granulosa cell complex. Therefore, a culture system was established that utilizes these complexes to assess mechanisms promoting nuclear, cytoplasmic and genomic maturation in mammalian oocytes. Deletion of serum from the culture, results in increased apoptosis in oocyte-associated granulosa cells (OAGCs), however, addition of ascorbic acid (0.5 mM) significantly reduced the level of apoptosis in the OAGCs, although no improvement of oocyte developmental competence was detected. The effects of reducing glucose during oocyte growth were studied since, under some culture conditions, glucose has deleterious effects on early preimplantation development. Reducing the glucose concentration to 1 mM resulted in the production of oocytes with greatly reduced developmental competence. Deleterious effects of FSH plus insulin during oocyte growth in vitro on preimplantation development are reviewed and discussed in terms of the communication of oocytes with inappropriately developing granulosa cells. Evidence that oocytes promote the appropriate differentiation of OAGCs in intact follicles in vivo is also discussed. It is hypothesized that oocytes control the differentiation of these cells, in order to promote intercellular signaling essential for the acquisition of competence to undergo normal embryogenesis.

Animals↗
PubMed2000

Rescue of oocytes from antral follicles of cryopreserved mouse ovaries: competence to undergo maturation, embryogenesis, and development to term.

Only primordial and primary follicles of frozen-thawed mouse ovaries survive after grafting to the ovarian bursa; large secondary follicles and antral follicles together with the oocytes contained in them degenerate. This study was undertaken to determine whether fully grown oocytes isolated from the antral follicles of frozen-thawed mouse ovaries are viable and can be rescued to undergo maturation, fertilization, and embryo development in vitro. Ovaries were cryopreserved after removal from 22-day-old (C57BL/6J x SJL/J)F(1) mice, with or without prior priming with equine chorionic gonadotrophin, and fresh non-frozen ovaries were used as controls. Only cumulus cell-denuded oocytes were recovered from frozen unprimed ovaries while both cumulus cell-enclosed and denuded oocytes were retrieved from frozen primed ovaries. Oocytes from both groups of frozen-thawed ovaries were able to undergo maturation, fertilization, and development to the blastocyst stage in vitro, though at lower percentages than oocytes from control unfrozen ovaries. Moreover, 19% of 2-cell stage embryos derived from frozen-thawed primed ovaries, compared with 42% of embryos derived from control primed ovaries, developed to term after transfer to pseudopregnant foster mothers (not significantly different). Therefore, fully grown oocytes in antral follicles survive the cryopreservation protocol, as demonstrated by maturation, fertilization and embryo development in vitro, and development to term after embryo transfer.

Animals↗
PubMed2000

Role of gut-enriched Krüppel-like factor in colonic cell growth and differentiation.

Cancer cells differ from normal cells in many aspects, including hyperproliferation and loss of differentiation. Recent research has focused on the role of transcription factors in regulating abnormal cell growth. Gut-enriched Krüppel-like factor (GKLF) is a newly identified eukaryotic zinc finger protein expressed extensively in the gastrointestinal tract. In the current study, we demonstrated that GKLF mRNA levels were significantly decreased in the dysplastic epithelium of the colon, including adenomatous polyp and cancer. GKLF immunostains in the normal colon were higher at the surface epithelium and gradually decreased toward the crypt, but this gradient was not present in the adenomatous and cancerous mucosa. Constitutive overexpression of GKLF DNA in a human colonic adenocarcinoma cell line (HT-29) decreased [(3)H]thymidine incorporation, whereas suppression of GKLF gene increased DNA synthesis, indicating that downregulation of the GKLF gene might contribute to cellular hyperproliferation. Cyclin D1 (CD1) protein level and CD1-associated kinase activity were decreased in HT-29 cell overexpressed GKLF cDNA, and CD1 promoter activity was profoundly suppressed by GKLF. When HT-29 cells were cultured in the presence of sodium butyrate, GKLF mRNA levels increased as cells acquired more differentiated phenotypes. These results suggest that GKLF plays an important role in regulating cell growth and differentiation in the colonic epithelium and that downregulation of GKLF expression may cause colonic cells to become hyperproliferative. Furthermore, GKLF appears to be a transcriptional repressor of the CD1 gene.

Adenomatous Polyposis Coli↗
PubMed2000

An assessment of digital image analysis to measure fibrosis in liver biopsy specimens of patients with chronic hepatitis C.

The aim was to assess the validity of a digitally computed fibrosis ratio as a measure of fibrosis stage in liver biopsy specimens. We scored 230 liver biopsy specimens from patients with chronic hepatitis C for fibrosis using modified Knodell criteria; fibrosis ratios were computed from digital images that encompassed the complete trichrome-stained section of each case. Although an overall correlation between fibrosis ratio and ordinal score was present, subset analysis showed that this correlation existed only among biopsy specimens with high scores (3-6, early bridging fibrosis to established cirrhosis). There was no correlation or difference between category means found among biopsy specimens with low scores (0-3, normal to early bridging fibrosis). Furthermore, concordance by both estimates in direction of fibrosis change among serial liver biopsy specimens was found in only 11 (30%) of 37 pairs compared. The findings suggest that a qualitative assessment of the computerized fibrosis pattern is necessary for the interpretation of computerized fibrosis ratio measurements, particularly in patients with early stage fibrosis.

Biopsy↗
PubMed1999

The role of p21ras in pancreatic neoplasia and chronic pancreatitis.

K-ras mutations have been detected in both ductal cell carcinoma and intraductal papillary mucinous tumor (IPMT) of pancreas. The frequency of this mutation in ductal cell carcinoma is high, whereas in IPMT, it is variable. It has been suggested that the relatively high frequency of this mutation in ductal cell carcinomas compared with IPMT may account for the differences in biological behavior between these tumor types. More recently, the significance of K-ras mutations in pancreatic tissue has been questioned with the demonstration of this mutation in nonneoplastic pancreata. The current study aims to estimate the relative frequency and evaluate the biological significance of K-ras gene mutations in these neoplasms by performing polymerase chain reaction (PCR) assays of microdissected areas of IPMT, ductal cell carcinomas, and resected chronic pancreatitis. The study also investigates whether alterations of p21ras occur in K-ras mutation-negative cases by using immunohistochemical staining for K-, N- and H-ras. K-ras codon 12 mutations were found almost as frequently in IPMT (71%) as in ductal cell carcinomas (78%). They were also associated with the earliest morphological lesion, flat mucinous change. This mutation also was detected in 42% of cases of chronic pancreatitis. Expression of p21ras was found to correlate closely with K-ras mutation status in IPMT and ductal cell carcinoma. Negative staining for pan-ras, H-ras, and N-ras in cases with wild-type K-ras genes suggests that alternative routes of ras gene alteration are not operative in IPMT or ductal carcinoma. The findings suggest that K-ras activation is frequently associated with both IPMT and ductal cell carcinoma. Its high prevalence in nonneoplastic pancreata suggests that it is also associated with self-limited morphological lesions of the pancreas that do not progress to malignancy.

Aged↗
PubMed1999

Epidermal growth factor enhances preimplantation developmental competence of maturing mouse oocytes.

The objective of this study was to determine whether epidermal growth factor (EGF) promotes nuclear and cytoplasmic maturation of mouse oocytes grown in vivo or in vitro. In-vivo-grown oocytes were isolated at the germinal vesicle (GV) stage from gonadotrophin-primed (PR) or -unprimed (UPR) 22-day-old mice before in-vitro maturation (IVM). In-vitro-grown (IVG) oocytes were isolated from preantral follicles of 12-day-old mice and grown in vitro without gonadotrophins for 10 days before maturation (IVG/IVM oocytes). IVM and IVG/IVM oocytes were matured in medium supplemented with either EGF (10 ng/ml), follicle stimulating hormone (FSH) (100 ng/ml), EGF plus FSH, or with neither ligand (control). When oocyte-cumulus cell complexes were isolated from PR and UPR mice, IVM with EGF (10 ng/ml), alone or in combination with FSH (100 ng/ml), increased (P < 0.05) the incidence of nuclear maturation to metaphase II. Cytoplasmic maturation of oocytes from PR females, manifested as increased frequency of cleavage to the 2-cell stage and development to the blastocyst stage, was also enhanced with EGF (P < 0.05). Moreover, EGF increased the number of cells per blastocyst, but only in the absence of FSH (P < 0.01). In contrast, EGF, FSH, or EGF plus FSH did not affect the percentage of oocytes from UPR mice completing preimplantation development, but did increase the number of cells per blastocyst. These ligands also increased the proportion of IVG oocytes reaching metaphase II (53-57%) compared with controls (25%; P < 0.05). EGF alone or in combination with FSH increased (P < 0.05) the frequency of blastocyst formation (23% and 28%, respectively) compared with controls (13%). EGF treatment of maturing IVG oocytes produced blastocysts with more cells than other IVG groups (P < 0.05). It is concluded that gonadotrophins in vivo increase the sensitivity or responsiveness of cumulus cell-enclosed oocytes to EGF, thereby promoting both nuclear and cytoplasmic maturation. However, oocyte-granulosa cell complexes grown in vitro become responsive to EGF without gonadotrophin treatment. Thus, nuclear and cytoplasmic maturation of IVG oocytes is promoted by EGF treatment during meiotic maturation.

Animals↗
PubMed1999

Comparison of protein synthesis patterns in mouse cumulus cells and mural granulosa cells: effects of follicle-stimulating hormone and insulin on granulosa cell differentiation in vitro.

Successful development of mammalian oocytes requires correct interactions between developing oocytes and associated granulosa cells. Development of oocyte-granulosa cell complexes from preantral follicles in vitro does not produce oocytes competent to develop to blastocysts at the same frequency as for oocytes that develop in vivo. Addition of either FSH or insulin to cultures of oocyte-granulosa cell complexes does not improve the frequency of blastocyst development, and the combination of both insulin and FSH is deleterious. Here, high-resolution 2-dimensional PAGE (2D-PAGE) and computerized gel image analysis were used to compare patterns of protein synthesis in cumulus cells and mural granulosa cells of small antral follicles, and then to assess effects of FSH and insulin on the differentiation of oocyte-associated granulosa cells (OAGCs) in vitro. Culture of OAGCs without FSH or insulin resulted in failure to synthesize many proteins at rates characteristic of cumulus cells. Either hormone used alone caused many cumulus cell proteins that were decreased in control cultures to be synthesized at nearly normal cumulus cell rates, and also caused the synthesis of other proteins to be increased or decreased. The two hormones added together produced the greatest change in protein synthetic pattern, including overexpression or underexpression of many proteins not affected by either hormone alone. Addition of these hormones to culture media thus appeared insufficient to elicit a normal cumulus cell phenotype in OAGCs and could lead to complex changes in protein synthesis that may be deleterious to oocyte development. The high-resolution 2D-PAGE approach described here should be a valuable tool in studies on oocyte and granulosa cell development in vitro, since phenotype can be evaluated globally through the display of over 1000 newly synthesized proteins rather than relying upon the expression of just a few genes.

Animals↗
PubMed1998

Comparison of preimplantation developmental competence after mouse oocyte growth and development in vitro and in vivo.

Culture systems for oocytes are essential for the experimental analysis of the basic mechanisms of oocyte development and, moreover, they will eventually find wide application in agriculture, the clinic, and wildlife preservation. Here, progress in mouse oocyte growth and development in vitro using oocyte-granulosa cell complexes from preantral follicles is reviewed. Oocyte-granulosa cell complexes were isolated from preantral (secondary) follicles of 12 day old mice, grown in vitro for 10 days, then matured and fertilized in vitro. The developmental competence of these oocytes was compared with oocytes grown in vivo and isolated from 22 day old mice, then matured and fertilized in vitro. In vitro-grown oocytes did not achieve the same size as their in vivo-grown counterparts. However, when oocytes were grown in medium containing fetal bovine serum, their preimplantation developmental competence was equivalent to that of in vivo-grown oocytes. Surprisingly, more blastocysts per animal were produced when oocytes were grown in vitro than in vivo. There was no correlation between oocyte size and either preimplantation developmental competence or number of cells per blastocyst. Oocytes grown in serum-free medium did not achieve the same developmental competence as oocytes grown in medium supplemented with serum. Lastly, the health status as an adult of the only animal born after complete oocyte development in vitro is described and discussed.

Animals↗
PubMed1998

Fine-needle aspiration cytology diagnosis of colloid nodule versus follicular variant of papillary carcinoma of the thyroid.

The cytologic differential diagnosis of colloid nodule (CN) and the follicular variant of papillary carcinoma (FVPC) is difficult with common morphologic features. To assess the utility of 18 cytologic morphometric parameters in the diagnosis of these thyroid lesions we evaluated 31 FNA samples that had histologic confirmation of the diagnoses. These 31 cases included 15 cases of CN, 8 cases of FVPC, and 8 cases of the usual variant of papillary carcinoma (UVPC) for reference values. For the morphometric analysis we used an Optimas 4.0 image analysis system. Comparing the CN group with the UVPC group revealed that eight of the parameters had statistically significant differences. The UVPC specimens were more cellular, less cohesive, had presence of papillary cellular groups more frequently, larger nuclei (UVPC: 109.33 +/- 30.19 microns2; CN: 66.81 +/- 15.02 microns2), higher nuclear to cytoplasmic (N/C) ratio, larger nucleoli, and present nuclear grooves and nuclear pseudoinclusions more frequently. The FVPC group differed from the CN group only in three parameters which included larger nuclei (98.49 +/- 18.24 microns2), higher N/C ratio, and a more frequent presence of nuclear pseudoinclusions. When we compared these two variants of papillary carcinoma, we found that the UVPC specimens had less cellular cohesion, less preservation of the architectural polarity and a more frequent presence of papillary cellular groups than the FVPC. The FVPC can be differentiated from CN based on nuclear changes, which included a larger size, higher N/C ratio, and presence of pseudoinclusions. The absence of cellular cohesion and polarity combined with the presence of papillary groups are useful in separating the UVPC from the FVPC. A cutoff of 75 microns2 should be used in separating benign from malignant nuclei.

Biopsy, Needle↗
PubMed1998

Factors affecting the developmental competence of mouse oocytes grown in vitro: follicle-stimulating hormone and insulin.

This study was undertaken to test the hypothesis that FSH treatment of cultured oocyte-granulosa cell complexes promotes acquisition of competence to complete preimplantation embryo development. Oocyte-granulosa cell complexes were isolated from the preantral follicles of 12-day-old mice and cultured for 10 days in serum-free medium, supplemented with insulin (5 microgram/ml), transferrin (5 microgram/ml), and selenium (5 ng/ml) and containing a highly potent preparation of FSH (0-5 ng/ml). Oocytes were matured and fertilized in vitro and embryos cultured to determine the frequency of development to the blastocyst stage. There was no effect of FSH on oocyte size, general morphology, or competence to resume meiosis. However, addition of FSH to medium containing insulin had a deleterious effect on the percentage of mature oocytes competent to develop to the blastocyst stage. Deletion of insulin from the medium for culture of oocyte-granulosa cell complexes prevented the deleterious effect of FSH, but FSH still did not promote acquisition of competence to complete preimplantation development. Culture of oocyte-granulosa cell complexes with FSH resulted in elevated expression of LH receptor (LHR) mRNA by granulosa cells and stimulated the production of functional LHRs, whether or not insulin was present. However, FSH-induced expression of LHR mRNA reached a maximum steady-state level by 4 days of culture in the presence of insulin, but this level was not reached until 10 days of culture without insulin. Granulosa cells encompassing growing mouse oocytes in vivo do not express LHR mRNA. Thus, expression of LHR mRNA by granulosa cells closely associated with growing oocytes in vitro indicates inappropriate or ambiguous development. In conclusion, conditions occurring during oocyte growth can have profound detrimental effects on oocyte developmental competence to complete preimplantation development, even when oocyte growth, general morphology, and competence to resume meiosis appear unaffected.

Animals↗
PubMed1997

Uptake and salvage of hypoxanthine mediates developmental arrest in preimplantation mouse embryos.

Preimplantation mouse embryos become arrested after first or second cleavage when cultured in hypoxanthine-supplemented Whitten's medium. We present evidence that the hypoxanthine-induced arrest is dependent on uptake and salvage of hypoxanthine and depletion of phosphoribosylpyrophosphate (PRPP) levels. Hypoxanthine uptake increased during the 2-cell stage and was augmented by glucose. HPLC analysis of [14C]hypoxanthine metabolism revealed that hypoxanthine was salvaged and converted to ATP and guanosine triphosphate (GTP), with a shift to more guanyl nucleotide production at the 3- to 4-cell stage. In embryos from mice with a null mutation for the salvage enzyme hypoxanthine-guanine phosphoribosyltransferase, hypoxanthine did not block development nor was it taken up by the embryos. Glucose, which is required for the hypoxanthine-induced arrest, produced a 5.3-fold increase in PRPP levels at the 2-cell stage, which was eliminated by hypoxanthine. We conclude that metabolism of hypoxanthine to nucleotides mediates its inhibitory action on preimplantation mouse embryos via negative feedback on PRPP synthetase, ultimately resulting in decreased PRPP availability and arrest of other PRPP-dependent pathways. Finally, reversal of the block by EDTA and cAMP-elevating agents may be mediated by alterations in hypoxanthine or glucose uptake, or by changes in the relative metabolism of hypoxanthine.

1-Methyl-3-isobutylxanthine↗
PubMed1997

Topoisomerase II alpha expression in normal, inflammatory, and neoplastic conditions of the gastric and colonic mucosa.

Topoisomerase II alpha (TP) excises and reconnects double-stranded super-coiled DNA during the replicative cell cycle. We studied the localization of TP and Ki-67 in inflammatory and neoplastic mucosal lesions of the stomach and of TP in similar conditions of the colon. TP expression was correlated with tumor stage, grade, and survival time in the colonic tumors to evaluate its potential utility as a predictive marker for clinical outcome. Forty-three sections of chronic gastritis, lesions indefinite for dysplasia, low- and high-grade dysplasia, and gastric adenocarcinomas were immunostained with antibody against TP and Ki-67. For the colon, 71 sections of normal mucosa, chronic colitis, hyperplastic polyps, adenomas, and carcinomas were examined; fresh tissue was analyzed by flow cytometry. Expression of TP in non-neoplastic gastric mucosa was maximal in neck/foveolar cells and focal in surface and deep gland cells. Increased surface and deep gland positivity was found in low-grade dysplasia and a diffuse distribution of positive cells in high-grade dysplasia and carcinoma. The Ki-67 staining pattern was similar. TP in non-neoplastic colon was restricted to the lower crypt zone; it was greatly expanded in the surface/upper crypt region in adenomas and was diffuse in carcinomas. Flow cytometric analysis revealed TP expression mainly in the S and G2/M phase, with higher labeling index in tumors. There was no correlation of TP with stage, grade, or survival times in the colonic tumors. Staining for TP and Ki-67 might help in the distinction of inflammatory and neoplastic lesions of the stomach and colon.

Antigens, Neoplasm↗
PubMed1997

Oocyte control of granulosa cell development: how and why.

Interaction between oocytes and granulosa cells is complex and involves both gap junctions and paracrine signalling factors. Oocyte development in antral follicles is highly dependent on communication with cumulus cells, a subset of granulosa cells that is intimately associated with oocytes. Cumulus cells express characteristics distinct from the mural granulosa cells of preovulatory follicles. The thesis of this paper is that, without the influence of oocytes, the pathway of granulosa cell differentiation in antral follicles leads to the establishment of the mural granulosa cell phenotype. Oocytes in antral follicles abrogate that pathway of granulosa cell differentiation and promote the development of the cumulus cell phenotype. Oocytes may do this in order to control their own microenvironment by regulating differentiation of the supporting cells that are in direct communication with them. Possibly, some aspects of the mural granulosa cell phenotype are antagonistic to, or insufficient for, supporting the final stages of oocyte development. We present evidence that oocytes control their environment by suppressing differentiation of the mural granulosa cell phenotype and promoting differentiation of the cumulus cell phenotype. They achieve this suppression via the secretion of labile paracrine signalling factors. Errors in this regulatory mechanism, whether instigated by defects in the production of oocyte-derived ligands or granulosa cell responses to them, may result in the production of oocytes unable to undergo embryo development or that undergo abnormal follicular development.

Cell Differentiation↗