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P Dockery

Publications and source records attributed to P Dockery.

At least 19 recordsLinked to original sources
PubMed2001

17beta-oestradiol stimulates capacitative Ca2+ entry in human endometrial cells.

Oestrogen plays an essential role in regulating growth and differentiation in the human endometrium which undergoes dynamic morphological and functional changes during the menstrual cycle in preparation for implantation. In this tissue, it has been suggested that intracellular calcium could be a key signal in transducing early responses to steroid hormones. Here, we have investigated the rapid effects of 17beta-oestradiol on [Ca2+]i in a human endometrial cell line (RL95-2). Using confocal imaging microscopy, we show that physiological concentrations of 17beta-oestradiol trigger rapid and transient increases in [Ca2+]i. Our results demonstrate that 17beta-oestradiol-induced [Ca2+]i variations are critically dependent on calcium influx via lanthanum-sensitive calcium channels. Moreover, the 17beta-oestradiol-induced Ca2+ influx is significantly increased by the depletion of intracellular stores by thapsigargin and decreased by chelerythrine chloride, an inhibitor of protein kinase C. These data indicate a non-genomic action of 17beta-oestradiol to stimulate capacitative Ca2+ entry through store-operated calcium channels via a PKC-sensitive pathway.

Alkaloids↗
PubMed2001

Early development of rat ventral root transitional zone: an immunohistochemical and morphometric study.

Bundles of ventral motoneuron axons cross the white matter of the spinal cord, emerge through the cord surface at the CNS-PNS transitional zone (TZ) and continue in the PNS as ventral rootlets. This study identifies immunohistochemical and morphometric changes which characterise the key events in early TZ formation in the rat. E18 is a landmark stage, since it is then that the major events of TZ differentiation are initiated. In the glial processes associated with the TZ, vimentin expression decreases, while that of GFAP increases. In the proximal rootlets the transient expression of CNS markers such as GFAP and of neural adhesion molecules such as HNK-1/N-CAM begin to decrease. Their resulting differential expression clearly defines the CNS-PNS interface. These changes coincide with the arrival of glial nuclei at the TZ. Cell clusters which appear on proximal ventral rootlet surfaces shortly after their emergence from the cord, have by E18 formed an extensive matrix of processes which segregates the axon bundle. This comprises the earliest of two well-defined barriers across the axon bundle. An important function may be to prevent Schwann cell invasion of the cord. Cluster cells display some immunohistochemical features in common with Schwann cells. The second barrier becomes fully established only at P2 and forms the definitive CNS-PNS interface. It consists of processes arising from astrocytes surrounding the TZ. Changes in the nuclear density of the cell types correspond closely to their segregating activity. The immunohistochemical and ultrastructural changes complement one another to deepen and enhance understanding of TZ development.

Animals↗
PubMed2000

Structure-function relations in the human placenta.

The human haemochorial placenta is a complex and dynamic interface between embryonic and maternal tissues. A myriad array of compounds has been identified at this interface, some of which exert local effects which might be important in maintaining the integrity of the organ. These compounds are diverse in nature and function; they include enzymes, hormones and bioactive peptides. Successful nidation requires the synchronization of endometrial maturation and embryonic development. The complex nature of this interface requires the application of sound sampling strategies. The new stereological methods have thrown fresh light on the growth and development of the human placenta. These methods permit the objective, quantitative description of morphology by efficient design-based methods. This approach has permitted a better definition of the functional morphology of the placenta. Applications of these methodologies are providing a spatial and temporal framework on which to lay the new physiological and molecular information. Here we review the essential features of the stereological approach, identify useful structural quantities and provide some examples of their application. The problems associated with the quantification of immunocytochemistry are illustrated with the use of immunoreactivity to insulin-like growth factor I receptor in normal placentae and in pre-eclampsia. Although stereology can provide useful quantitative information about the structure of this dynamic tissue, other anatomical methods that could be applied to better define the relationships between structure and function will be discussed. These include confocal microscopy, to examine the dynamic physiological interactions of the different tissue compartments, and low-temperature electron microscopy techniques such as cryosubstitution, to allow better access to the biochemical information resident in the tissue. The complex and dynamic nature of the tissue requires a multidisciplinary approach; central to these investigations is a comprehensive understanding of its fine structure.

Estradiol↗
PubMed1999

Morphological evidence for the 'implantation window' in human luminal endometrium.

Endometrial tissue was taken from 21 normal fertile women (aged 18-40 years) between 4 and 13 days after the luteinizing hormone (LH) surge. Systematic random samples of luminal epithelium were taken for both light and electron microscopy and examined morphometrically. Throughout the luteal phase there were remarkably few changes in the volume fraction of nucleus, mitochondria, rough endoplasmic reticulum and 'vesicular system' to cell. Nuclear profile dimensions and cell height also did not change over time. Cell and organelle volume (estimated as volume weighted mean volume) did not change significantly, but showed numerically smallest values on day LH + 13. However the ratio of desmosomes to whole cell and both arithmetic mean thickness and harmonic mean thickness of basement membrane were minimal at the time when implantation would be most likely to occur, i.e. approximately 6 days after the LH peak. Therefore it appears that while some morphometric parameters in human luminal epithelial cells change little during the luteal phase, specific cellular changes occur to the basement membrane and desmosomes which may facilitate embryo implantation. These changes occurred around day LH+ 6 and may be a morphological representation of the 'implantation window'.

Adolescent↗
PubMed1998

The ventral motoneurone axon bundle in the CNS--a cordone system?

In the developing CNS neighbouring structures are commonly separated by transient barriers termed cordones, some of which coincide with glial elements. Where ventral motoneuron axons cross the spinal white matter as intramedullary bundles to reach the CNS-PNS transitional zone they are surrounded from early development by a glial sleeve resembling a cordone. This becomes better developed with age and, like some cordones, persists into adult life. This could provide a radial conduit which might underlie the capacity of central segments of mature ventral motoneurone axons to regenerate. It may also provide a pathway for glial migration from the central cord to more superficial levels, including the transitional zone, where they help form the CNS-PNS barrier. Axons in the intramedullary bundle and in the surrounding ventral white column mature at different rates. Glial sleeve cells of the intramedullary bundles are apposed to both. Morphometric analysis of the axon-glial relationships of the two populations indicates that glial development proceeds at a different rate in relation to each axon class and that this is influenced by the degree of axonal maturation, which may in turn be related to target contact. Furthermore, early axon glial relationships differ between the two populations. For ventral motoneurone axons these take place in two stages: firstly, glial segregation of axons (resembling that in the PNS) and secondly, oligodendrocytic contact and ensheathment, which leads on to myelination. Axon-glial relationships in the ventral white column begin with the second of these events, as is more typical of early CNS myelination in general.

Age Factors↗
PubMed1998

A strong myelin thickness-axon size correlation emerges in developing nerves despite independent growth of both parameters.

The axon determines whether or not it is myelinated by the Schwann cell. At maturity there is a positive correlation between sheath thickness and axon calibre. This correlation is initially very low or absent, but gradually strengthens during development. This increase could come about because the axon continuously controls Schwann cell myelinating activity, so that a given axon calibre is associated with a particular myelin sheath thickness, an interaction which would entail the Schwann cell continuously monitoring and responding to axon size. This seems unnecessarily complex. This theoretical study shows that the strong correlation between the 2 parameters within a given myelinated fibre population may come about in a much simpler way than outlined above. This is demonstrated by modelling the growth and myelination of a hypothetical population, utilising data from earlier studies on cervical ventral motoneuron axon development. The hypothesis tested shows that the only instructive interactions by the axon on the Schwann cell necessary for the strong correlation between the 2 parameters to emerge are for the initiation of myelination, its continuation and its termination. These could result from a single stimulus being switched on, persisting for a time and being switched off. Under this influence, the Schwann cell is assumed to proceed to form the myelin sheath at a constant rate which it itself inherently determines, in the absence of any quantitative influence exerted by the axon. This continues until the stimulus for myelination ceases to emanate from the axon. The validity of the hypothesis is demonstrated, because the resulting myelin-axon relationships correspond closely to those observed during development.

Animals↗
PubMed1998

Stereological studies of the effects of alpha-MSH and cAMP on melanosomes in melanoma cells.

The effects of alpha-MSH and cAMP on melanosomes in Cloudman S91 melanoma cells were investigated by modern stereological techniques. Cells were cultured for 4 days in medium containing alpha-MSH or cAMP, harvested at 24 hour intervals; some were frozen for melanin assay and the reminder embedded in Epon for light and electron microscopy. Cellular and melanosomal parameters were estimated by new stereological probes. We found that both stimulators induced increases in nuclear volume, cell volume, and the volume fractions and volumes of premelanosomes (V(Vpm,cell), Vpm) and mature melanosomes (V(Vmm,cell), Vmm), and the number of mature melanosomes (Nmm). Both stimulators also caused declines in the volume of individual mature melanosomes (V(Vimm)), the melanin content per mature melanosome unit volume and the melanin content per individual mature melanosome. The increases in the volume of individual premelanosomes and the number of premelanosomes were only induced by cAMP. The effect cAMP on some parameters occurred 24 hours prior to alpha-MSH and was more marked. The response of premelanosomes to the stimulators was more sensitive than mature melanosomes. These results suggest that both stimulators enhanced melanogenesis by increasing the V(Vpm,cell), V(Vmm,cell), Vpm, Vmm and Nmm. The melanogenic level did not depend on the V(Vimm) and melanin concentration in melanosomes. The maturation of premelanosomes was involved in melanogenesis induced by both stimulators, but, de novo synthesis and enlargement of premelanosomes were only stimulated by cAMP. It imply that exogenous cAMP may affect melanosomes, and hence melanogenesis in quantitatively or qualitatively different ways to alpha-MSH.

Cell Count↗
PubMed1997

Neuron volume in the ventral horn in Wobbler mouse motoneuron disease: a light microscope stereological study.

Previous pathological reports have indicated that swollen and vacuolated motoneuron cell bodies are the most predominant feature characterising Wobbler mouse motoneuron disease, but there has been little supportive evidence using area measurements. The present study focuses on the possible role of changes in neuronal nuclear and perikaryal volumes in the cervical spinal cord ventral horn, using new and traditional stereological probes which provide unbiased estimates of volume. Semithin sections from the ventral horn of Wobbler mice and age and sex-matched phenotypically normal littermates were examined at 2 ages (young and old). The young Wobbler group had significantly larger volume weighted mean perikaryal volumes compared with age-matched controls, reflecting the presence of large swollen cells characteristic of this group; this situation was reversed in the control group. Number-weighted perikaryal volume estimates in the old Wobbler group were smaller than in age-matched controls. The variation in perikaryal volume was greatest in the young Wobbler group in which the coefficient of variation was 127%. The mean number weighted and volume weighted mean nuclear volumes were significantly smaller in the old Wobbler group compared with age-matched controls and young Wobbler groups. The application of new stereological probes has enabled us to document more precisely these changes in neuronal structure in the Wobbler mutant mouse.

Aging↗
PubMed1997

The effect of a single dose of mifepristone (RU486) on the fine structure of the human endometrium during the early luteal phase.

This study examined the fine structure of the human endometrial glandular epithelium after the administration of a single dose of RU486 (mifepristone), given in the early luteal phase. The drug was administered on days 2, 3, 5 and 6 after the luteinizing hormone peak (LH + 0). Biopsies were performed on days LH + 5, 6, 8 and 9. These were compared with control biopsies taken on corresponding days. Qualitatively, the main cytological effect of the RU486 was on the secretory apparatus and on the polarity of the cell. The formation of the nuclear channel system was also affected by the drug. A two-way analysis of variance on cell and nuclear volume data revealed no significant effect of day of biopsy, condition or interaction. Mitochondrial volume and secretory apparatus volume data revealed a significant effect of day of biopsy and interaction term; mitochondrial volume at LH + 5 was 95.9 +/- 25.3 microm3 (mean +/- SD) for control and 57.7 +/- 31.9 microm3 for RU486-treated epithelium. The volume of the secretory apparatus in the treated group was smaller on days LH + 5 and 6 (14.6 +/- 4.2 microm3, 6.41 +/- microm3) when compared to day-matched control biopsies (35.9 +/- 10.5 microm3, 41.7 +/- 26.4 microm3). RU486 administration in the early luteal phase disrupted the secretory activity of the cells. These findings provide an insight into the cellular mechanisms of progesterone receptor blockade in the peri-implantation period.

Adolescent↗
PubMed1996

Changes in nuclear morphology in the human endometrial glandular epithelium in women with unexplained infertility.

In the light and electron microscopical study reported here, we documented the structure of the nucleus, nucleolus and nuclear channel system (NCS) in the uterine glandular epithelium in both fertile and infertile women during the early luteal phase. Nuclear volume was found to be larger in the infertile group at day 5 after the luteinizing hormone surge (LH+5) compared to day-matched fertile subjects. A two-way analysis of variance performed on nucleolar volume data from fertile and infertile women biopsied on days LH+5, +5, and +6 revealed a significant effect of condition but no effect of day or interaction. Nucleolar volume decreased from day LH+2 to day LH+6 in the fertile group, the sharpest decrease occurring between day LH+3 and day LH+4. The largest mean volume of the NCS was found at day LH+5 in the fertile group and day LH+6 in the infertile group. The results suggest a delay in the development of this organelle in the infertile women. The present study has documented alterations in the nuclei of uterine glandular cells from infertile patients. In these infertile women, there is also a delayed elaboration of the secretory apparatus and this delay correlates well with the delayed/reduced expression of a luteal-specific glyco-protein.

Analysis of Variance↗
PubMed1996

A quantitative study of silver-stained NORs in different segments of the normal human colorectal crypt.

Quantification of silver-stained nucleolar organiser regions (AgNORs) in paraffin sections may provide clues about the proliferation and differentiation in normal and neoplastic tissues. The aim of the present investigation was to determine whether AgNOR quantification could provide useful data about proliferation in the different segments of the normal human colorectal crypt. Samples of histologically 'normal' large intestine (n = 8) were obtained from colorectal cancer resections at a distance of > 5 cm from the tumour margins and were routinely processed for paraffin embedding using strictly standardised procedures. Sections were cut and stained with a one-stage silver colloid impregnation technique. The longitudinally sectioned crypts were divided into proliferative (P), intermediate (I) and surface (S) segments using strict criteria. Clearly defined AgNORs, which appeared as black dots within the nuclear profile, were quantified from each segment for volume density (Vv) and number per unit area (NA) estimates using traditional point-counting techniques. A 1-way analysis of variance followed by Scheffe's test indicated significant progressive reductions of AgNOR Vv and NA from P to S segments. Our data suggest that both volume and frequency of AgNORs may be related to cellular proliferation since both parameters are highest in the P segment. The further exploitation of stereological tools in conjunction with AgNOR staining may be valuable in assessing normal differentiation and proliferation patterns and in predicting the biological behaviour of neoplastic tissues in which increased proliferation is a feature.

Aged↗
PubMed1996

The human ovarian granulosa cell: a stereological approach.

The human ovarian granulosa cell is perhaps the most widely studied endocrine cell, but little quantitative structural information exists for this cell. In the present study new and traditional stereological probes have been employed to provide quantitative structural information on these functionally important cells. Granulosa cells were obtained from follicular aspirations from 10 women during in vitro fertilisation procedures. Initially 2 methods were used to estimate the mean nuclear volume of these cells: the mean number weighted nuclear volume was estimated by the Selector and the mean volume weighted nuclear volume by the point sampled intercept method. It was found that the difference between the 2 volume estimates was only 8.5%. The volume weighted mean nuclear volume was used as an estimate of nuclear volume. This was subsequently corrected (taking the percentage difference as the empirical bias) and combined with fractional cell volumes (Vv) to produce estimates of cell, mitochondrial, lipid and nucleolar volume. The proportion of the cell occupied by the nucleus had a remarkably low interindividual variation (CV = 7.6%). The proportion of the nucleus occupied by euchromatin also had a striking low variation (CV < 6%). All other cellular parameters had CVs of less than 35%. The lipid composition of these cells showed the greatest interindividual variability, with a CV of 42% for relative and 54% for absolute volume. The present study outlines a simple protocol for the quantitation of granulosa cell structure using new unbiased stereological probes and providing baseline structural information.

Cell Nucleus↗
PubMed1994

Effects of male accessory sex glands on fertilization, polyspermy and morphometry of early embryos in the golden hamster.

Preimplantation embryos sired by hamsters without accessory sex glands (ASG) were found to have a higher mortality rate and a slower cleavage rate than those sired by sham-operated males at 72 h post coitum (p.c.). A time-course study of fertilization in vivo was conducted to determine whether this effect was due to delayed fertilization. Ultrastructural morphometry of 48 h embryos was also undertaken to establish the earliest manifestation of developmental anomalies. Compared to sham-operated controls (SH), ablation of all the ASG (TX), or just the ventral prostate (VPX) or ampullary gland (AGX) had no effect on the timing of sperm penetration, extrusion of the second polar body and pronuclear formation. Females mated with AGX males tended to have more polyspermic embryos (9.7%; p < 0.05). The volumes, volume fractions (VV) of the blastomere nuclei, mitochondria and yolk material of the four-cell embryos sired by these same groups of males were assessed using point counting techniques. No difference in the VV of yolk and mitochondria could be observed between groups. However, the SH group did have a significantly larger proportion of the cell occupied by the nucleus (p < 0.05), and the TX group had a higher proportion of the nucleus occupied by nucleoli when compared with the SH group (p < 0.01). Smaller nuclei and larger nucleoli in the TX group was interpreted as an early manifestation of a slower division rate of the blastomeres.

Animals↗
PubMed1993

The fine structure of the human endometrial glandular epithelium in cases of unexplained infertility: a morphometric study.

In the present study attempts have been made to express in quantitative terms the fine structure of the endometrial glandular epithelium in well-timed biopsies from fertile women during the early luteal phase. Biopsies from women with unexplained infertility have also been examined. Certain abnormalities of glandular maturation were found in these women. The nuclear channel system was not present at day luteinizing hormone (LH) + 4 in the infertile group while at LH + 6 there were more cells containing this feature than seen in the fertile group. There also seem to be abnormalities associated with intracellular deposits of glycogen-rich material and mitochondrial elaboration in the infertile women. Changes in the secretory apparatus and rough endoplasmic reticulum were observed. The evidence from the present study suggests that the endometria in the examined group of infertile women is responsive to steroidal stimulation. This response however, may be delayed or inadequate.

Cell Nucleus↗
PubMed1992

The endometrial biopsy as a predictive factor of pregnancy rate in women with unexplained infertility.

To investigate whether or not there is any relation between endometrial morphology and subsequent pregnancy rate, 47 couples with unexplained infertility were followed up for 3 years after they had had an endometrial biopsy. Each woman had an LH-timed endometrial biopsy performed in the luteal phase of the cycle. The biopsy was dated chronologically according to the luteinizing hormone (LH) surge and histologically using morphometric criteria. None of the women received any form of treatment in the endometrial biopsy cycle. Of 47 women with unexplained infertility, 36 (76.6%) (Group I) had 'in phase' endometrial development and 11 (23.4%) (Group II) had retarded endometrium. Women with normal endometrial development had a higher pregnancy rate than women with retarded endometrial development (50% vs. 9%; P less than 0.02). The fecundability during treatment cycles was higher in Group I than in Group II (0.051 vs. 0.008; P less than 0.05). In women with 'in phase' endometrium, treatment increased the monthly probability of conception (0.051 vs. 0.006; P less than 0.001). A precisely timed endometrial biopsy should be considered as part of the investigations for women with unexplained reproductive failure, to help determine prognosis.

Adult↗
PubMed1992

Endometrial responses in artificial cycles: a prospective, randomized study comparing three different progesterone dosages.

OBJECTIVE: To examine the endometrial response to three different regimens of progesterone. DESIGN: A prospective, randomized study. SETTING: The Jessop Hospital for Women, Sheffield. SUBJECTS: 14 women with premature ovarian failure divided into two equal groups. INTERVENTIONS: Three different regimens of hormone replacement therapy containing standard, high and low progesterone dosages. One group received the standard regimen in one cycle and high dosage regimen in another cycle. The second group received the standard regimen in one cycle and low dosage regimen in another cycle. The order of the two dosage regimens was randomized by lottery. MAIN OUTCOME MEASURES: Ultrasonographic measurement of endometrial thickness and morphological study of endometrial biopsy specimens taken on day 19 of the cycle using the traditional dating criteria and morphometric techniques. RESULTS: Compared with standard regimen cycles, the endometrial response in cycles treated with the low dosage regimen showed significant retardation of overall endometrial development and changes in a number of morphometric measurements. The response of endometrial glands to the high dosage regimen was similar to that of the standard regimen, although the stromal cell diameter was increased. CONCLUSIONS: In women receiving hormone replacement therapy normal endometrial development depends on an adequate dosage of progesterone, but increased dosage above our standard regimen does not produce any further change in the glandular component of the endometrium.

Adult↗
PubMed1991

A morphometric study of the uterine glandular epithelium in women with premature ovarian failure undergoing hormone replacement therapy.

In this study we examined the fine structure of the human glandular epithelium in women with idiopathic ovarian failure in artificial cycles produced by two different types of hormone replacement therapy (oestradiol valerate orally and either intramuscular injection of progesterone or progesterone via vaginal pessary), both of which had been claimed to be capable of supporting successful implantation. Biopsies were performed on day 19 of the artificial cycle. A variety of sterological probes were used to quantify the structural characteristics of these cells and the results obtained were compared with those from normal fertile subjects biopsied on days 2 and 5 after the luteinizing hormone (LH) surge. The glandular epithelial cells from the vaginal group had a less elaborate secretory apparatus when compared with the intramuscular group or with LH + 5 controls. Many of the features of the vaginal group suggested a continued oestrogenic influence, while the intramuscular group seemed to be more advanced than LH + 5.

Cell Nucleus↗