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Current techniques for three-dimensional (3D) optical microscopy (deconvolution, confocal microscopy, and optical coherence tomography) generate 3D data by “optically sectioning” the specimen. This places severe constraints on the maximum thickness of a specimen that can be imaged. We have developed a microscopy technique that uses optical projection tomography (OPT) to produce high-resolution 3D images of both fluorescent and nonfluorescent biological specimens with a thickness of up to 15 millimeters. OPT microscopy allows the rapid mapping of the tissue distribution of RNA and protein expression in intact embryos or organ systems and can therefore be instrumental in studies of developmental biology or gene function.

Article-at-a-Glance Background Despite the considerable attention that health care organizations are devoting to the measurement of patient satisfaction, there is often confusion about how to systematically use these data to improve an organization's performance. A model to use in applying traditional quality improvement methods and tools to patient satisfaction problems includes five primary steps: (1) identifying opportunities, (2) prioritizing opportunities, (3) conducting root cause analysis, (4) designing and testing potential solutions, and (5) implementing the proposed solution. Patient satisfaction surveys A satisfaction survey serves best as a high-level screening device, not as a tool to provide highly detailed information about the root causes of patient dissatisfaction. The primary purpose of the survey in the model is to identify improvement opportunities and areas of significant improvement or deterioration. Secondary tools such as brief patient interviews or focus groups may better serve to probe intensively into the problem areas identified by the survey. These tools allow for a direct dialog with the patient to uncover root causes of dissatisfaction and establish potential solutions. Discussion Although the primary focus of this model has been patient satisfaction issues, the basic steps could easily be applied to virtually any improvement opportunity. Improvement teams should commit to a schedule of 90-minute weekly meetings for 7 weeks. The model, a simple translation of traditional improvement methods and tools to address the unique issues facing patient satisfaction improvement teams, can save improvement teams considerable time, resources, and frustration as they design and launch initiatives to improve patient satisfaction.

Anti-coagulated patients are monitored at regular intervals to ensure that their warfarin dosage is appropriate for their target International Normalized Ratio. The traditional setting for this monitoring has been the hospital clinic. Technological advances allow-- and with growing numbers of anti-coagulated patients, are leading to-- greater provision of monitoring clinics outside the hospital, at a more convenient location nearer patients' homes. This paper discusses the differences in organization between a hospital clinic and one set in the community (although provided by the hospital), and compares their costs. The comparison demonstrates the greater average cost per appointment in outreach of pound sterling 13.12 under current arrangements. Estimates are presented of incremental cost per appointment of pound sterling 3.93 and pound sterling 15.88 for a 10% increase in weekly patient numbers put through hospital and outreach clinics, respectively. Cost estimates are also presented for suggested alterations to hospital clinics that may reduce patient inconvenience, and the conditions under which outreach provision might be expanded at comparable cost to hospital provision are also examined.

Aniridia in man and Small eye in mice are semidominant developmental disorders caused by mutations within the paired box gene PAX6. Whereas heterozygotes suffer from iris hypoplasia, homozygous mice lack eyes and nasal cavities and exhibit brain abnormalities. To investigate the role of gene dosage in more detail, we have generated yeast artificial chromosome transgenic mice carrying the human PAX6 locus. When crossed onto the Small eye background, the transgene rescues the mutant phenotype. Strikingly, mice carrying multiple copies on a wild-type background show specific developmental abnormalities of the eye, but not of other tissues expressing the gene. Thus, at least five different eye phenotypes are associated with changes in PAX6 expression. We provide evidence that not only reduced, but also increased levels of transcriptional regulators can cause developmental defects.

WT1 is a tumor suppressor gene with a key role in urogenital development and the pathogenesis of Wilms' tumor. Two alternative splice sites in the WT1 transcript allow the gene to encode four proteins. These carry four Krüppel-type zinc fingers and to date have primarily been implicated in transcriptional control of genes involved in growth regulation. However, here we demonstrate colocalization of WT1 with splicing factors in the fetal kidney and testis and in expressing cell lines. Using immunoprecipitation, we show that two WT1 isoforms directly associate with one or a limited number of components in the spliceosomes and coiled bodies. Moreover, COS cell expression studies suggest that alternative splicing within the WT1 zinc finger region determines whether the protein localizes mainly with splicing factors or with DNA in transcription factor domains in the nucleus. We propose that WT1 plays roles in posttranscriptional processing of RNA as well as in transcription.

eMouseAtlas (www.emouseatlas.org) is a comprehensive online resource to visualise mouse development and investigate gene expression in the mouse embryo. We have recently deployed a completely redesigned Mouse Anatomy Atlas website (www.emouseatlas.org/emap/ema) that allows users to view 3D embryo reconstructions, delineated anatomy, and high-resolution histological sections. A new feature of the website is the IIP3D web tool that allows a user to view arbitrary sections of 3D embryo reconstructions using a web browser. This feature provides interactive access to very high-volume 3D images via a tiled pan-and-zoom style interface and circumvents the need to download large image files for visualisation. eMouseAtlas additionally includes EMAGE (Edinburgh Mouse Atlas of Gene Expression) (www.emouseatlas.org/emage), a freely available, curated online database of in situ gene expression patterns, where gene expression domains extracted from raw data images are spatially mapped into atlas embryo models. In this way, EMAGE introduces a spatial dimension to transcriptome data and allows exploration of the spatial similarity between gene expression patterns. New features of the EMAGE interface allow complex queries to be built, and users can view and compare multiple gene expression patterns.EMAGE now includes mapping of 3D gene expression domains captured using the imaging technique optical projection tomography. 3D mapping uses WlzWarp, an open-source software tool developed by eMouseAtlas.

International audience; In the mouse embryo the anterior ectoderm undergoes extensive growth and morphogenesis to form the forebrain and cephalic non-neural ectoderm. We traced descendants of single ectoderm cells to study cell fate choice and cell behaviour at late gastrulation. In addition, we provide a comprehensive spatiotemporal atlas of anterior gene expression at stages crucial for anterior ectoderm regionalisation and neural plate formation. Our results show that, at late gastrulation stage, expression patterns of anterior ectoderm genes overlap significantly and correlate with areas of distinct prospective fates but do not define lineages. The fate map delineates a rostral limit to forebrain contribution. However, no early subdivision of the presumptive forebrain territory can be detected. Lineage analysis at single-cell resolution revealed that precursors of the anterior neural ridge (ANR), a signalling centre involved in forebrain development and patterning, are clonally related to neural ectoderm. The prospective ANR and the forebrain neuroectoderm arise from cells scattered within the same broad area of anterior ectoderm. This study establishes that although the segregation between non-neural and neural precursors in the anterior midline ectoderm is not complete at late gastrulation stage, this tissue already harbours elements of regionalisation that prefigure the later organisation of the head.

We report 3 years of experience with quarterly assessments of the self-reported health of dialysis outpatients using the Short Form-36 (SF-36) Health Survey. The SF-36 measures eight different dimensions of health: physical function, role limitations due to physical problems, bodily pain, general health perceptions, vitality, social function, role limitations due to emotional problems, and general mental health. On each dimensions, the respondent receives a score from 0 to 100. A higher score indicates better health. Program logistics and results are described, including reliability coefficients, standard deviations, and standard errors of measurement for the SF-36 in this patient population. The SF-36 was completed an average of 4.4 times by 112 patients over an average 14-month follow-up; 40 patients responded at least six times. On most dimensions, the dialysis patients' scores were lower and more variable than those of a sample of the general US population matched for age and sex. For example, mean initial physical function score (+/- SD) was 48.5 +/- 31.2 for the dialysis patients and 84.8 +/- 23.3 for the general population. The mean initial general health perception score of the dialysis patients was 43.7 +/- 23.9 with 71.9 +/- 20.3 for the general population. In contrast, general mental health scores were more comparable. The mean initial general mental health score was 69.6 +/- 17.5 for our patients and 75.5 +/- 18.0 for the general population. Reliability (Cronbach's alpha) ranged from 0.77 for general mental health to 0.93 for physical function. The 95% confidence intervals around individual scores were approximately 20 points, except for role-physical and role-emotional, which were both approximately 30 points. Two case reports compare information obtained from the SF-36 with the dialysis team's assessments of the patient, as recorded in the medical record. The two patients' comments on reviewing their SF-36 results are also summarized. Patient reactions to the health status assessment program are explored, and potential benefits and areas for further work are outlined. Serial measurement of the health status of dialysis patients allows the recognition of clear patterns in individual patient responses. These patterns sometimes suggest that the patient is either substantially more or less impaired than the dialysis team had thought. Changes in these patterns, both transient and protracted, frequently exceed 95% confidence intervals for patient-level scores. Longitudinal health status profiles of individual dialysis patients, accumulated by repeated self-assessment using the SF-36, enhance rather than merely restate the providers' intuitive judgments expressed in the medical record.

Congenital anomalies of the kidney and urinary tract (CAKUTs) are common disorders of human development affecting the renal parechyma, renal pelvis, ureter, bladder and urethra; they show evidence of shared genetic aetiology, although the molecular basis of this remains unknown in the majority of cases. Breakpoint mapping of a de novo, apparently balanced, reciprocal translocation associated with bilateral renal agenesis has implicated the gene encoding the nuclear steroid hormone receptor ESRRG as a candidate gene for CAKUT. Here we show that the Esrrg protein is detected throughout early ureteric ducts as cytoplasmic/sub-membranous staining; with nuclear localization seen in developing nephrons. In 14.5 – 16.5 dpc (days post-conception) mouse embryos, Esrrg localizes to the subset of ductal tissue within the kidney, liver and lung. The renal ductal expression becomes localized to renal papilla by 18.5 dpc. Perturbation of function was performed in embryonic mouse kidney culture using pooled siRNA to induce knock-down and a specific small-molecule agonist to induce aberrant activation of Esrrg. Both resulted in severe abnormality of early branching events of the ureteric duct. Mouse embryos with a targeted inactivation of Esrrg on both alleles (Esrrg 2/2 ) showed agenesis of the renal papilla but normal development of the cortex and remaining medulla. Taken together, these results suggest that Esrrg is required for early branching events of the ureteric duct that occur prior to the onset of nephrogenesis. These findings confirm ESRRG as a strong candidate gene for CAKUT.

This paper describes the initial development of a patient-based outcomes assessment program in an outpatient dialysis unit. This project presented four logistical and practical issues that are discussed in this paper: patient acceptance of quarterly administrations of a generic health status survey (the SF-36); timing of administration during dialysis session; respondent burden; and staff burden. Also discussed are three issues related to the clinical use of these assessments: medical record status of SF-36 data; use in clinical decisionmaking; and clinicians' responses to aggregate data from patient-based health status assessments. The investigation reported presents strong evidence of patient acceptance of the SF-36. Data collection problems reflected the nature of a busy dialysis unit, and most have been corrected. Considering functional status, the role functioning of dialysis patients is most adversely affected; among well-being measures, patients are most compromised by pain and lack of energy. Clinicians' reviews of these results point to the need for normative data, information about severity of primary and comorbid diseases, and knowledge of relationships between SF-36 scores and physiologic parameters to make clinical use of generic health outcome assessments.

During the 1980s both the federal government and the private sector articulated policies to encourage the development and participation of health maintenance organizations (HMOs) in the Medicaid program. However, the policies, intended to save costs, limited the ability of new HMOs to achieve financial independence. New plans that emphasize Medicaid participation have few, if any, options on benefit design or in setting capitation rates. Relative to fee-for-service Medicaid programs, their costs to provide services may be quite high, as they have neither the buying power nor the ability to impose discounts. As a consequence, plans must focus their financial planning efforts on targeting and attaining a stable enrollment base and on controlling the amount of services provided, tasks that are difficult for all HMOs. Achieving a stable enrollment base is particularly hard because Medicaid eligibles have few incentives to enroll and once enrolled often lose their Medicaid eligibility. Traditional HMOs control the amount of services provided through physician selection, financial incentives on physicians, and monitoring and utilization review. Lack of information and the difficulty inherent in attracting sufficient provider participation limit the first two strategies, so new plans often adopt organization structures that rely heavily on monitoring activities. Unfortunately, management information systems for HMOs are often the weakest link. We discuss the tasks and present data on financial planning, on putting financial plans into operation, and on monitoring progress toward financial independence for a set of ten demonstration projects sponsored by the Robert Wood Johnson Foundation.

Mouse kidney induction proceeds in vitro much as it does in vivo: the ureteric bud bifurcates to give collecting ducts while the mesenchyme condenses into aggregates which epithelialise and then elongate into tubules with glomerular and other nephron structures. We report here that the factor known as LIF (leukaemia inhibitory factor), which regulates the differentiation and growth of embryonic-stem (ES) and other cells in culture, has little effect in vitro on growth or on ureteric-bud morphogenesis other than to stimulate the bifurcation process. It does however exert a striking effect on the mesenchyme. At about four times the concentration required to inhibit ES-cell differentiation, LIF strongly but reversibly blocks the effects of metanephric mesenchyme induction: although mesenchyme condenses around growing duct tips, the number of mature nephrons that form over 6 days is reduced by 75% or more. The few nephrons that do develop in the presence of LIF probably come from mesenchyme already induced at the time of culture and are indistinguishable from those that form in controls as assayed by morphology, by X-gal staining of endogenous galactosidase and by antibodies to brush-border and CD15 antigens. There is a further unexpected feature of rudiments cultured in LIF which is absent in controls: they contain an unexpectedly high number of stable epithelialised aggregates that express laminin around their periphery and which do not develop further. These results argue that the process of nephrogenesis involves at least two distinct stages which can be blocked by LIF: the effect of the initial induction and the future development of epithelialised aggregates.(ABSTRACT TRUNCATED AT 250 WORDS)

The Edinburgh MouseAtlas Project (EMAP) is a time-series of mouse-embryo volumetric models. The models provide a context-free spatial framework onto which structural interpretations and experimental data can be mapped. This enables collation, comparison, and query of complex spatial patterns with respect to each other and with respect to known or hypothesized structure. The atlas also includes a time-dependent anatomical ontology and mapping between the ontology and the spatial models in the form of delineated anatomical regions or tissues. The models provide a natural, graphical context for browsing and visualizing complex data. The Edinburgh Mouse Atlas Gene-Expression Database (EMAGE) is one of the first applications of the EMAP framework and provides a spatially mapped gene-expression database with associated tools for data mapping, submission, and query. In this article, we describe the underlying principles of the Atlas and the gene-expression database, and provide a practical introduction to the use of the EMAP and EMAGE tools, including use of new techniques for whole body gene-expression data capture and mapping.

In the present study, it is shown that mice heterozygous for wt1 develop glomerular sclerosis and the nature and time course of events leading to the glomerular scarring are determined. Wt1-heterozygous (wt1het) mice and their wild-type littermates were closely monitored from birth and plasma levels of urea, creatinine, and albumin were compared with histological data and clinical features. One of the first indications of nephropathy in the wt1het mouse was the development of proteinuria, accompanied by progressive elevation of the plasma levels of urea and creatinine. Subsequently, the mice developed albuminuria, which correlated with thickening of the glomerular basement membrane and fusion of the podocyte foot processes. Glomerulosclerosis was a relatively late event, accompanied by severe albuminuria and loss of WT1, nephrin, CD2AP, and alpha-actinin-4.

The authors conducted a randomized controlled trial of functional disability screening in a hospital-based internal medicine group practice. They assigned 60 physicians and 497 of their patients to either an experimental or a control group. Every four months the patients in both groups completed a self-administered questionnaire measuring physical, psychological, and social function. The experimental group physicians received reports summarizing their patients' responses; the control group physicians received no report. At the end of one year the authors found no significant difference between the patients of the experimental and control group physicians on any measure of functional status. Functional disability screening alone does not improve patient function.

Article-at-a-Glance Background The focus of this article is on health-related outcomes, particularly reducing symptoms and improving health status. Public policy, purchaser demand, quality assurance/quality improvement, clinical research, and the computerized medical record have all fed the increasing interest in outcomes. “Outcomes assessment” refers to the measurement, monitoring, and feedback of outcomes. In implementing outcomes assessment, the bulk of the work is concentrated in managing individual projects. From May 1992 through March 1993, under a grant from the Functional Outcomes Program of the New England Medical Center (Boston), the directors of five major health outcomes assessment programs held a series of meetings to share their experiences in implementation. Principles and recommended best practices for project management are provided here. Implementing an outcomes project Making a commitment to begin includes identifying a condition or procedure to investigate, assembling a project team, and naming a coordinator. Designing a project entails defining its purpose and scope, developing the measurement instruments, and establishing a logistical protocol for data collection. Managing the data entails collecting the data, entering the data into a database, maintaining quality control over the data, and storing the data. Using the data entails analyzing the data, providing feedback and interpretation to clinicians, and linking outcomes to the clinical process. Case study For a typical outcomes project–total hip replacement–the sequence of activities in the project and the staffing and resources needed are all described.

The term health care researcher refers to a diverse set of professionals, academicians, and policymakers who study topics related to the organization, process, quality, and outcomes of health services delivery. This chapter concentrates on the uses and requirements of those who focus on medical care services, including mental health services but excluding dental care. Among the disciplines who work in health care research are clinicians (physicians, nurses, psychiatrists, clinical psychologists, and clinical social workers), economists, research psychologists, sociologists, political scientists, and epidemiologists, in addition to those trained specifically in public health and health services research.

Continuous patient feedback can give important information to hospitals about the quality of care they provide. The Patient Comment Card (PCC), a brief form that can be used to gather open-ended comments from patients and to measure quality, was developed during a two-year period and was extensively evaluated in a series of three pilot tests involving more than 2,000 patients discharged from five hospitals. Evaluation results demonstrate that the questionnaire elicits useful comments from patients and can generate statistically reliable scores and valid quality measures. However, in a field trial in four hospitals, low response rates (15%-27%) reflected, first, lack of follow-up of non-respondents, and second, the fact that most of the PCC quality scores were upwardly biased; these inflated scores were likely to reflect the low response rate. Tools such as the PCC should be used judiciously, given the possible abuses and misinterpretations of hospital quality scores.

To assess the ability of internists to identify functional disabilities reported by their patients.Comparison of responses by physicians and a random sample of their patients to a 12-item questionnaire about physical and social function.A hospital-based internal medicine group practice in Boston, Massachusetts, and selected office-based internal medicine practices in Los Angeles, California.Five staff physicians, three general internal medicine fellows, and 34 internal medicine residents in the hospital-based practice and 178 of their patients. Seventy-six physicians in the office-based practices and 230 of their patients.Physicians underestimated or failed to recognize 66% of disabilities reported by patients. Patient-reported disabilities were underestimated or unrecognized more often in the hospital-based practice than in the office-based practices (75% compared with 60%, P less than 0.05). Physicians overstated functional impairment in 21% of paired responses in which patients reported no disability.Physicians often underestimate or fail to recognize functional disabilities that are reported by their patients. They overstate functional impairment to a lesser degree. Because these discrepancies may adversely affect patient care and well-being, medical educators and clinicians should pay more attention to the assessment of patient function.

Longitudinal data from The Rand Corporation's Health Insurance Experiment were used to test the hypothesis that provider continuity can be modeled as one behavioral consequence of patient satisfaction. Bivariate and multivariate analyses (controlling for sociodemographic characteristics, prior use of services, health status, and health insurance plan) supported our hypotheses. A multivariate linear probability function indicated that a 1-point decrease on a general satisfaction scale was associated with a 3.4 percentage-point increase in the probability of provider change. The relationship between satisfaction scores and continuity during the following year appears to be roughly linear; we observed no "threshold" satisfaction level at which the probability of provider change increased markedly. We discuss needed improvements in the measurement of provider continuity and the need for further study of other behavioral consequences of patient satisfaction.

This article describes improvements in the immunohistologic technique for embedding highly hydrated embryonic tissue in polyethylene glycol 1000 (PEG)--a water-soluble wax of melting point 39 degrees C--and compares the PEG sections with frozen and polyester-wax sections. The main improvement ensures that relatively large PEG sections (8 X 3 mm) stretch out and adhere well to slides: a coat of albumen and glycerine is dried onto the slides and a fresh coat applied just before use. The embedding, sectioning, and mounting procedures, which are considerably faster than those for wax processing, have been developed for screening monoclonal antibodies against the differentiated neural crest cells in the anterior eyes of 9-day-old chick embryos. PEG sections of such eyes were a little fragile, but showed good cellular detail, similar to or better than in wax sections and considerably better than in frozen sections. The responses of PEG sections to the antibodies were far stronger than those of wax and marginally better than those of frozen sections. In one experiment using 125I-labeled rabbit anti-mouse antibody on sections previously treated with antibodies or antisera, PEG sections bound about five times as much label as wax sections and approximately 30% more than frozen sections. The main limitation of the technique is that, because of the softness of PEG, it only works well for embedding a limited range of tissues. Such PEG sections may, however, be useful for in situ hybridization as well as for immunohistochemistry.

The present study compares patient satisfaction scores with job satisfaction scores of the physicians providing their care in 16 general internal medicine teaching hospital group practices. Practice sites with more satisfied patients were also more likely to have more satisfied housestaff and faculty physicians. Additionally, higher satisfaction scores for both physician groups and patients were consistently associated with a greater percentage of patients experiencing continuity of care, lower patient no-show rates, more efficient use of ancillary staff in providing direct patient care, and more reasonable charges for a routine follow-up visit. These findings suggest that improving physician and patient satisfaction may have economic as well as psychological and social benefits.

Millipore 'discs' impregnated with methylcholanthrene dissolved in wax or in crystalline form implanted subcutaneously in mice evoke an early intense macrophage and giant cell reaction; later the discs become covered with connective tissue, and eventually fibrosarcomas develop in their vicinity. Studies with tritium-labelled material show that under these conditions methylcholanthrene (MC) is removed from the discs and broken down rapidly (half life about 7 days) to a water-soluble product, which diffuses locally, is distributed widely via the blood stream, and is excreted in faeces and urine. Removal of label is halted by whole-body irradiation (550 R) with the disc area shielded; this observation, in conjunction with the histological and autoradiographic findings and the paucity of label in cells stripped from excised discs, points to the conclusion that the removal of MC from impregnated discs, and its subsequent degradation, depend on the presence of macrophages and the continual replacement of spent macrophages by new cells generated centrally. The rate of disappearance of label from implanted [ 3 H]MC discs was not altered by administration of Corynebacterium parvum ; this, however, does not exclude the possibility that the metabolic pathways involved in the removal of MC are altered. To investigate this it is proposed to study, in both normal mice and mice treated with C. parvum , the extent to which cytochrome P450 and other enzymes concerned in the activation and detoxification of polycyclic hydrocarbons by liver microsomal fractions are inducible in the macrophages that accumulate in inflammatory exudates. The histological techniques used should be readily applicable to the study of the early stages of chemical carcinogenesis and the host reaction to transformed cells.

This paper describes development of a 19-item self-administered Dental Satisfaction Questionnaire (DSQ). Item and factor analyses supported construction and separate scoring of 5 scales (Access. Availability/Convenience, Cost, Pain, and Quality) representing major sources of satisfaction and dissatisfaction with dental care providers and services. A global access scale and an overall dental satisfaction index were also constructed. Scale scores are sufficiently reliable to be used to compare different groups of patients or to study one group over time. Several lines of evidence support the validity of scale scores. Taken together, the results suggest that the DSQ will be useful in general population studies of dental care attitudes, and that dentists may do a better job than physicians in satisfying their patients.

This paper offers suggestions to adi the selection of appropriate instruments and data gathering methods for studies that require measures of personal health status applicable in general populations. Before selecting measures, the reason for studying health status must be identified. Next, definitional issues arise when attempting to specify the components of health that are to be studied. Evidence supports restriction of the definition of personal health status to its physical and mental components, rather than including social circumstances as well. In evaluating the suitability of available measures, three features must be considered: 1) practicality in terms of administration, respondent burden, and analysis; 2) reliability in terms of the study design and group or individual comparisons; 3) validity, in terms of providing information about the particular health components of interest to the study. Evaluating validity will be difficult for most available measures; careful attention to item content will be helpful in choosing appropriate measures. Despite problems in development and interpretation, overall health status indicators will prove useful to many studies and should be considered, as should both subjective and objective measures of health status. Given that the reasons to measure health have been identified, the aspects of health to be measured specified, and attention paid to their suitability, appropriate measures may often be found among those now available.

The morphogenetic mechanism responsible for the radial folding of the anterior retina of the chick eye as it forms the ciliary body has been investigated in two ways. First, eye growth and cell division have been assayed to find out the origins of the extra fold material, and second, possible mechanisms have been tested, and in some cases excluded, by artificially increasing the size of the embryonic eye in vitro under a range of restrictive conditions. Growth studies show that, while on average the eyeball increases linearly in area by a factor of about 14 over the period 4–8 days or stages 24–33, there is a slowing down in growth at stage 28 which is followed by a rapid catch up as the surface area increases by about two-thirds in the 12 hr between stages 29 and 30, just as the ciliary body forms. Thymidine incorporation studies show that cell division is roughly uniform over the eye at this stage. The sudden increase in the overall size of the eye is not, however, matched by growth in the region of the pupil at the retinal tip; this ring of tissue grows slowly and its diameter remains virtually constant over the period of ciliary body morphogenesis. These observations suggest a simple morphogenetic mechanism. Tissue near the retinal tip, unlike such tissue in the rest of the eye, is unable to swell uniformly under intraocular pressure as it is constrained by the rigid pupillary ring; the resulting complex tensions cause radial folding. This process is facilitated by lateral cell detachment in the neural retinal epithelium (NRE) and nucleated by existing radial capillaries superficial to the retina. It is a prediction of the mechanism that any differential growth of the eyeball should cause stage 29 eyes to fold. Such growth has been induced in vitro by immersing early stage 29 eyes in 50% ethanol and water, a solution which causes an 8% or so increase in eye diameter in a few minutes, equivalent to about several hours growth in vivo. Pupillary expansion, however, lags some 15 min behind that of the rest of the eye. In most cases, immersed eyes generate large numbers of radial folds over about half their circumference in about 10 min after immersion, the degree of folding expected for similar growth in vivo. This result argues against morphogenetic mechanisms based on localised growth or on other slow developmental events. Such radial fold formation in vitro after treatment of eyes in vivo with colchicine and cytochalasin B has also been observed, results which argue against any morphogenetic mechanism based on microtubules or microfilaments. Some folds also form with ethanol swelling after the cornea and peripheral mesenchyme have been removed from the eye, a result which excludes any major directive role for this part of the tissue. The observations therefore support the simple differential growth stimulus for ciliary body morphogenesis.