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PubMed1990

A combination of cytological and architectural morphometry in assessing regenerative hyperplasia and dysplasia in ulcerative colitis.

Morphometry and stereology were used to assess the cytological and architectural characteristics of regenerative and dysplastic colorectal mucosal abnormalities in ulcerative colitis. Reproducibility of measurements was assessed and found to be good, confirming the objective and reproducible nature of morphometric analysis. Discriminant analysis between the morphometric features of regenerative mucosal change and low-grade dysplasia revealed the significant cytological and architectural variables from which a cytological and architectural score were derived. The architectural score was capable of classifying all of the cases into their correct diagnostic category, although a combination of the two scores provided better separation of cases. Probability density analysis was carried out so that probabilities of group membership could be allocated to cases, given their cytological and architectural scores. Discriminant analysis was also applied to low- and high-grade dysplasia. Important cytological and architectural variables were identified and used separately to derive scoring systems. In combination, the dual scoring of lesions was capable of separating low- from high-grade dysplasia, although overlap was still evident. Again, probability density analysis allowed the allocation of cases into one or other category, although a closer examination showed that such a rule could not successfully classify a new set of low- and high-grade dysplasia cases. Quantitative histological analysis of mucosal abnormalities is shown to be of use in the objective diagnosis of reactive and dysplastic change in patients with ulcerative colitis. The use of simple scoring systems and probability based allocation of cases promotes the future role of morphometric techniques in the diagnostic laboratory.

Bayes Theorem↗
PubMed2001

Selection of an optimal neural network architecture for computer-aided detection of microcalcifications--comparison of automated optimization techniques.

Many computer-aided diagnosis (CAD) systems use neural networks (NNs) for either detection or classification of abnormalities. Currently, most NNs are "optimized" by manual search in a very limited parameter space. In this work, we evaluated the use of automated optimization methods for selecting an optimal convolution neural network (CNN) architecture. Three automated methods, the steepest descent (SD), the simulated annealing (SA), and the genetic algorithm (GA), were compared. We used as an example the CNN that classifies true and false microcalcifications detected on digitized mammograms by a prescreening algorithm. Four parameters of the CNN architecture were considered for optimization, the numbers of node groups and the filter kernel sizes in the first and second hidden layers, resulting in a search space of 432 possible architectures. The area Az under the receiver operating characteristic (ROC) curve was used to design a cost function. The SA experiments were conducted with four different annealing schedules. Three different parent selection methods were compared for the GA experiments. An available data set was split into two groups with approximately equal number of samples. By using the two groups alternately for training and testing, two different cost surfaces were evaluated. For the first cost surface, the SD method was trapped in a local minimum 91% (392/432) of the time. The SA using the Boltzman schedule selected the best architecture after evaluating, on average, 167 architectures. The GA achieved its best performance with linearly scaled roulette-wheel parent selection; however, it evaluated 391 different architectures, on average, to find the best one. The second cost surface contained no local minimum. For this surface, a simple SD algorithm could quickly find the global minimum, but the SA with the very fast reannealing schedule was still the most efficient. The same SA scheme, however, was trapped in a local minimum on the first cost surface. Our CNN study demonstrated that, if optimization is to be performed on a cost surface whose characteristics are not known a priori, it is advisable that a moderately fast algorithm such as a SA using a Boltzman cooling schedule be used to conduct an efficient and thorough search, which may offer a better chance of reaching the global minimum.

Algorithms↗
PubMed1990

Systems architecture for quantification of dynamic myoelectric and kinematic activity of the human vocal tract.

This paper describes a systems architecture useful for scientific investigations that require the acquisition and analysis of multiple, time-synchronous signals in large volume. The architecture has recently been developed by this group to enhance our capability to research and quantify central nervous system function in the production of normal and pathologic speech. The architecture utilizes modern advances in desktop microcomputers and has been designed so that vocal motor control laboratories (or similar settings) with modest funding can more fully participate in comprehensive investigations of speech production. Research experiments organized with this architecture may involve many more subjects and measures than previously possible without significant increases in time and personnel resources. This paper will demonstrate the technique and practicality of this architecture as it is being used to successfully guide research to map hierarchic central nervous system regions of involvement in two speech disorders: spasmodic dysphonia and stuttering. The architecture has broad usefulness to many areas of otolaryngology and health science.

Adult↗
PubMed2003

Deterioration of trabecular architecture in hypogonadal men.

Bone strength depends on trabecular architecture, characterized by interconnected plates and rods. In osteoporosis, the plates become fenestrated, resulting in more rods that deteriorate and become disconnected. In men, hypogonadism is a common cause of osteoporosis. To determine whether male hypogonadism affects trabecular architecture, we selected 10 men with severe, untreated hypogonadism, and for each hypogonadal man, we selected a eugonadal man matched for race and age. Trabecular architecture in the distal tibia was assessed by magnetic resonance microimaging. Two composite topological indices were determined: the ratio of surface voxels (representing plates) to curve voxels (representing rods), which is higher when architecture is more intact; and the erosion index, a ratio of parameters expected to increase upon architectural deterioration to those expected to decrease, which is higher when deterioration is greater. The surface/curve ratio was 36% lower (P = 0.004), and the erosion index was 36% higher (P = 0.003) in the hypogonadal men than in the eugonadal men. In contrast, bone mineral density of the spine and hip were not significantly different between the two groups. We conclude that male hypogonadism is associated with marked deterioration of trabecular architecture and to a greater degree than bone densitometry of the spine and hip suggests.

Absorptiometry, Photon↗
PubMed2005

Effect of testosterone replacement on trabecular architecture in hypogonadal men.

UNLABELLED: We evaluated the effect of testosterone treatment on trabecular architecture by microMRI in 10 untreated severely hypogonadal men. After 2 years, microMRI parameters of trabecular connectivity improved significantly, suggesting the possibility that testosterone improves trabecular architecture. INTRODUCTION: Osteoporosis, characterized by low BMD and diminished bone quality, is a significant public health problem in men. Hypogonadal men have decreased BMD and deteriorated trabecular architecture compared with eugonadal men, and testosterone treatment improves their BMD. We tested the hypothesis that testosterone replacement in hypogonadal men would also improve their trabecular architecture. MATERIALS AND METHODS: We selected 10 untreated severely hypogonadal men and treated them with a testosterone gel for 24 months to maintain their serum testosterone concentrations within the normal range. Each subject was assessed before and after 6, 12, and 24 months of testosterone treatment by magnetic resonance microimaging (microMRI) of the distal tibia and by DXA of the spine and hip. The microMRI parameters reflect the integrity of the trabecular network and include the ratio of all surface voxels (representing plates) to curve voxels (representing rods) and the topological erosion index, a ratio of topological parameters expected to increase on trabecular deterioration to those expected to decrease. The higher the surface-to-curve ratio and the lower the topological erosion index, the more intact the trabecular network. RESULTS: Serum testosterone concentrations increased to midnormal after 3 months of treatment and remained normal thereafter. After 24 months of testosterone treatment, BMD of the spine increased 7.4% (p<0.001), and of the total hip increased 3.8% (p=0.008). Architectural parameters assessed by microMRI also changed: the surface-to-curve ratio increased 11% (p=0.004) and the topological erosion index decreased 7.5% (p=0.004). CONCLUSIONS: These results suggest the possibility that testosterone replacement of hypogonadal men improves trabecular architecture.

Adolescent↗
PubMed2000

Evaluation of changes in trabecular bone architecture and mechanical properties of minipig vertebrae by three-dimensional magnetic resonance microimaging and finite element modeling.

The study objective was to analyze the three-dimensional (3D) trabecular architecture and mechanical properties in vertebral specimens of young and mature Sinclair minipigs to assess the relative contribution of architecture to bone strength. We used 3D magnetic resonance microimaging (MRmicroI) and direct image analysis to evaluate a set of standard structural measurements and new architectural descriptors of trabecular bone in biopsy specimens from L2, L3, and L4 vertebrae (n = 16 in each group) from young (mean age, 1.2 years) and mature (mean age, 4.8 years) minipigs. The measurements included bone volume/tissue volume (BV/TV), marrow star volume (Ma.St.V), connectivity density (ConnD), and two new parameters, percent platelike trabeculae (% plate) and percent bone in the load direction (% boneLD). The % plate, calculated from surface curvature, allowed the delineation of plates from rods. The % boneLD quantified the percentage of bone oriented along the long axis of the vertebral body. We showed that 3D MRmicroI can detect the subtle changes in trabecular architecture between the two age groups. ConnD, star volume, % plate, % boneLD, and BV/TV were found to be more effective than the model-based, derived indices (trabecular thickness [Tb.Th], trabecular separation [Tb.Sp], and trabecular number [Tb.N]) in differentiating the structural changes. BV/TV, % plate, and % boneLD significantly increased (p < 0.05) in all three vertebral sites of the mature minipigs. The significant decrease in ConnD and star volume in the mature vertebra was consistent with the concurrent increase of platelike trabecular bone (p < 0.05). Overall, ConnD, star volume, % plate, and % boneLD provided a coherent picture of the architectural changes between the two age groups. Apparent modulus and maximum stress were determined experimentally on biopsy specimens from L2 vertebrae (n = 16). When apparent modulus was predicted using 3D MRmicroI data sets as input for finite element modeling (FEM), the results were similar to the experimentally determined apparent modulus (p = 0.12). Both methods were then used to compare the young and the mature animals; the experimental and predicted apparent modulus were significantly higher for the mature group (p = 0.003 and 0.012, respectively). The experimental maximum stress in the vertebra of the mature animals was twice as high as that for the young animals (p = 0.006). Bone quantity (BV/TV or bone mineral content [BMC]) alone could explain approximately 74-85% of the total variability in stress and modulus. The inclusion of either ConnD or % boneLD with BV/TV in a multiple regression analysis significantly improved the predictability of maximum stress, indicating that architecture makes additional contributions to compressive strength in normal minipig vertebra.

Aging↗
PubMed2005

The evolution of genetic architecture. I. Diversification of genetic backgrounds by genetic drift.

The genetic architecture of a phenotype plays a critical role in determining phenotypic evolution through its effects on patterns of genetic variation. Genetic architecture is often considered to be constant in evolutionary quantitative genetic models. However, genetic architecture may be variable and itself evolve when there are dominance and epistatic interactions among alleles at the same and different loci, respectively. The evolution of genetic architecture by genetic drift is examined here by testing the breeding value of four standard inbred mouse strains mated across a set of 26 related recombinant quasi-inbred (RqI) lines generated from the intercross of the Large (LG/J) and Small (SM/J) inbred mouse strains. Phenotypes of interest include age-specific body weights, growth, and adult body composition. If the genetic architecture of these traits has differentiated by genetic drift during the production of the RqI strains, we should observe interactions between tester strain and RqI strain. The breeding values of the tester strains will change relative to one another depending on which RqI strain they are crossed to. The study included an average of 15.1 offspring per cross, over a total of 100 different crosses. Multivariate and univariate analyses of variance indicate that there is strongly significant interaction for all traits. Interaction is more pronounced in males than in females and accounted for an average of about 40% of the explained variation in males and 30% in females. These results indicate that the genetic architecture of these traits has differentiated by genetic drift in the RqI strains since their isolation from a common founder population. Further analysis indicates that this differentiation results in changes in the order of tester strain effects so that common patterns of selection in these differentiated populations could result in the fixation of different alleles.

Animals↗
PubMed1997

Diagnostic performance characteristics of architectural features revealed by high spatial-resolution MR imaging of the breast.

OBJECTIVE: Our objective was twofold: to determine which architectural features revealed by high spatial-resolution MR imaging of the breast contribute to diagnostic accuracy and to evaluate the diagnostic performance characteristics of those architectural features. MATERIALS AND METHODS: Eligible patients with suspicious mammographic or palpable findings or both underwent MR imaging. Ninety-three patients whose MR images revealed lesions that corresponded to the mammographically visible or palpable findings were included in the study. Patients were examined with sagittal T1-weighted spin-echo MR imaging, fat-saturated T2-weighted fast spin-echo MR imaging, and dynamically enhanced fat-saturated fast gradient-echo MR imaging. All patients underwent subsequent excisional biopsy or cyst aspiration. Lesions were identified initially by an experienced radiologist who was aware of the patient's clinical or mammographic information. Two radiologists who were unaware of the patients' histories and who had less experience in MR imaging of the breast then independently evaluated each lesion for the architectural-features and predicted each lesion's potential for malignancy. RESULTS: Architectural features that were highly predictive of benign disease included smooth or lobulated borders (97-100%), the absence of mass enhancement (100%), and enhancement that was less than the enhancement of surrounding breast fibroglandular tissue (93-100%). Nonenhancing internal septations were specific for the diagnosis of fibroadenoma. Architectural features that were highly predictive of malignant disease included spiculated borders (76-88%) and peripheral rim enhancement in the presence of central lesion enhancement (79-92%). CONCLUSION: Architectural features revealed by high spatial-resolution MR imaging of the breast can help distinguish benign from malignant disease.

Adult↗
PubMedDate not supplied

How architecture wins technology wars.

Signs of revolutionary transformation in the global computer industry are everywhere. A roll call of the major industry players reads like a waiting list in the emergency room. The usual explanations for the industry's turmoil are at best inadequate. Scale, friendly government policies, manufacturing capabilities, a strong position in desktop markets, excellent software, top design skills--none of these is sufficient, either by itself or in combination, to ensure competitive success in information technology. A new paradigm is required to explain patterns of success and failure. Simply stated, success flows to the company that manages to establish proprietary architectural control over a broad, fast-moving, competitive space. Architectural strategies have become crucial to information technology because of the astonishing rate of improvement in microprocessors and other semiconductor components. Since no single vendor can keep pace with the outpouring of cheap, powerful, mass-produced components, customers insist on stitching together their own local systems solutions. Architectures impose order on the system and make the interconnections possible. The architectural controller is the company that controls the standard by which the entire information package is assembled. Microsoft's Windows is an excellent example of this. Because of the popularity of Windows, companies like Lotus must conform their software to its parameters in order to compete for market share. In the 1990s, proprietary architectural control is not only possible but indispensable to competitive success. What's more, it has broader implications for organizational structure: architectural competition is giving rise to a new form of business organization.

Computer Systems↗
PubMedDate not supplied

Will architecture win the technology wars?

Success today flows to the company that establishes proprietary architectural control over a broad, fast-moving, competitive space, Charles R. Morris and Charles H. Ferguson claim in "How Architecture Wins Technology Wars" (March-April 1993). No single vendor can keep pace with the outpouring of cheap, powerful, mass-produced components, so customers have been stitching together their own local systems solutions. Architectures impose order on the system and make interconnections possible. An architectural controller has power over the standard by which the entire information package is assembled. Because of the popularity of Microsoft's Windows, for example, companies like Lotus must conform their software to its parameters to be able to compete for market share. Proprietary architectural control has broader implications for organizational structure too: architectural competition is giving rise to a new form of business organization.

Computer Systems↗
PubMed1999

[Histomorphometric measurement of the architecture of the trabecular bone in osteoporosis: comparative study of several methods].

Osteoporosis is now defined as a disease characterized by a decreased bone mass associated with micro-architectural modification of trabecular bone leading to an increased fragility and to bone fractures. Various histomorphometric methods have been described to measure bone architecture on histological sections. However, not all of methods are strictly equivalent and some of them appear able to detect differences earlier in the course of the disease. We have compared 8 histomorphometric methods known to characterize the architecture of trabecular bone in 55 male osteoporotic patients. Measurements were done on transiliac bone biopsies: Trabecular number, thickness and separation (Tb.N, Tb.Th, Tb.Sp); Trabecular Bone Pattern Factor (TBPf); Euler-Poincaré's number (E); Interconnectivity Index (ICI); strut analysis of the trabecular network with the ratio of nodes/free-end (N/F); star volume of the bone marrow (Vm) and trabeculae (Vtrab) and the Kolmogorov fractal dimension of the trabecular boundaries (D). Relationships between the various architectural parameters were studied by hierarchical cluster analysis. Linear, hyperbolic and exponential correlations were found between trabecular bone volume (BV/TV) and architectural parameters. Cluster analysis demonstrates the link between these architectural parameters. ICI, E and TBPf which reflect the amount of open/closed marrow cavities clustered together and appeared related to Tb.Sp, which are indicators of the mean size of marrow cavities. Tb.Th, Vm and N/F flocked together as they reflect the trabecular size. Tb.N and D segregated together and seemed to best describe the trabecular network complexity. These histomorphometric techniques are correlated but correlations may be linear or non linear. Several histomorphometric techniques need to be used in parallel to appreciate the pathophysiological mechanisms of osteoporotic states.

Bone and Bones↗
PubMed2000

Technology architecture guidelines for a health care system.

Although the demand for use of information technology within the healthcare industry is intensifying, relatively little has been written about guidelines to optimize IT investments. A technology architecture is a set of guidelines for technology integration within an enterprise. The architecture is a critical tool in the effort to control information technology (IT) operating costs by constraining the number of technologies supported. A well-designed architecture is also an important aid to integrating disparate applications, data stores and networks. The authors led the development of a thorough, carefully designed technology architecture for a large and rapidly growing health care system. The purpose and design criteria are described, as well as the process for gaining consensus and disseminating the architecture. In addition, the processes for using, maintaining, and handling exceptions are described. The technology architecture is extremely valuable to health care organizations both in controlling costs and promoting integration.

Computer Systems↗
PubMed2005

Security architecture for health grid using ambient intelligence.

OBJECTIVES: To propose a novel approach of incorporating ambient intelligence in the health grid security architecture. METHODS: Security concerns are severely impeding the grid community effort in spreading its wings in health applications. In this paper, we have proposed a high level approach to incorporate ambient intelligence for health grid security architecture and have argued that this will significantly improve the current state of the grid security paradigm with an enhanced user-friendly environment. We believe that the time is right to shift the onus of traditional security mechanisms onto the new technologies. The incorporation of ambient intelligence in the security architecture of a grid will not only render a security paradigm robust but also provide an attractive vision for the future of computing by bringing the two worlds together. RESULTS: In this article we propose an evolutionary approach of utilizing smart devices for grid security architecture. We argue that such an infrastructure will impart unique features to the existing grid security paradigms by offering fortified and relentless monitoring. This new security architecture will be comprehensive in nature but will not be cumbersome for the users due to its typical characteristics of not prying into their lives and adapting to their needs. CONCLUSIONS: We have identified a new paradigm of the security architecture for a health grid that will not only render a security mechanism robust but will also provide the high levels of user-friendliness. As our approach is a first contribution to this problem, a number of other issues for future research remain open. However, the prospects are fascinating.

Access to Information↗
PubMedDate not supplied

Architectural barriers to persons with disabilities in businesses in an urban community.

It is the purpose of this study to determine the frequency of architectural barriers to persons with disabilities in businesses in a small urban community in central Virginia. The survey was conducted by a trained volunteer using a one-page checklist. Only 27% of the businesses had no architectural barriers to individuals with disabilities. The most common architectural barrier for individuals with disabilities was the interference with parking and entrance into the business (65%). Faced with these architectural barriers, all individuals are encouraged to identify the architectural barriers in businesses and to file letters of complaints to the Department of Justice requesting their removal.

Architectural Accessibility↗
PubMedDate not supplied

Comparison of eight histomorphometric methods for measuring trabecular bone architecture by image analysis on histological sections.

Osteoporosis is defined as a disease characterized by low bone mass and microarchitectural deterioration of trabecular bone leading to enhanced bone fragility. Various histomorphometric methods have been described to measure bone architecture on histological sections. However, not all of the methods are strictly equivalent and some of them appear able to detect differences earlier in the course of the disease. We have compared 8 histomorphometric methods known to characterize the architecture of trabecular bone in 154 male osteoporotic patients. Measurements were done on transiliac bone biopsies: Trabecular number, thickness, and separation (Tb.N, Tb.Th, Tb.Sp); Trabecular Bone Pattern Factor (TBPf); Euler-Poincare's number (E); Interconnectivity Index (ICI); strut analysis of the trabecular network with the ratio of nodes/free-end (N/F); star volume of the bone marrow (V*m.space) and trabeculae (V*Tb) and the Kolmogorov fractal dimension of the trabecular boundaries (D). Relationships between the various architectural parameters were studied by hierarchical cluster analysis. Linear, hyperbolic, and exponential correlations were found between trabecular bone volume (BV/TV) and architectural parameters. Cluster analysis demonstrates the link between these architectural parameters. ICI, E, and TBPf, which reflect the amount of open/closed marrow cavities clustered together and appeared related to Tb.Sp, V*m.space which are indicators of the mean size of marrow cavities. Tb.Th, V*Tb and N/F flocked together as they reflect the trabecular size. Tb.N and D segregated together and seemed to best describe the trabecular network complexity. These histomorphometric techniques are correlated but correlations may be linear or nonlinear. Several histomorphometric techniques need to be used in parallel to appreciate the pathophysiological mechanisms of osteoporotic states.

Adult↗
PubMed1998

Architecture of the cancellous bone of the human talus.

The trabeculae of the cancellous bone are formed along the direction of the lines of stresses to which a bone is subjected. The talus sustains the weight of the body and transmits the weight in different directions (i.e., the calcaneus and navicular). The aim of the present study was to investigate the architecture of the cancellous bone of the talus to understand the mechanism of transmission of force within the bone. Twenty-five dry, macerated tali of adult male humans were used to study the trabecular architecture. In a few bones, serial longitudinal (parasagittal), transverse (coronal), and horizontal sections were cut; in other bones, the trabecular bone was exposed by removal of cortical bone. Trabecular architecture was studied by dissection microscope and by taking radiographs of the slices. The body of the talus consisted of vertical, parallel plates arranged posteroanteriorly. This kind of orientation of the plates facilitates the transmission of weight, when the tibia rolls posteroanteriorly on the trochlear surface during walking. The trabecular architecture in the head of talus consisted of semiarched plates running parallel to each other. The vertical limb of these semiarched plates were situated above the middle and anterior calcaneal facets on the plantar surface of the head, whereas the horizontal limbs of the arches were deep to the navicular articular surface of the head. The vertical plates of the body and semiarched plates of the head were interconnected by a meshwork of irregularly arranged trabecular bone of the neck. The architecture of this meshwork was such that it could facilitate the change in the direction and nature of force. In conclusion, the part of compressive force, acting vertically downward on the body of the talus during standing, was converted to tensile force in the neck, and its direction was made perpendicular to enable this force to go toward the head of the talus. In a similar manner, the semiarched pattern of plates in the head facilitated the change in the direction of the force, at the end of the stance phase, from the downward (toward calcaneus) to the forward (toward navicular) direction.

Heel↗
PubMed1996

Cellular sociology applied to neuroendocrine tumors of the lung: quantitative model of neoplastic architecture.

This paper reports on cellular sociology, which consists of modeling tissular architecture based on graph theory. Voronoi's diagram was chosen to build the models. This diagram derives from a cell neighborhood concept and generates parameters which objectively represent tissue architecture. Minimal spanning tree (MST) is probably the more frequently used among graphs and successfully discriminates different grades of pathological process. However, Voronoi's diagram is more comprehensive and a more complete representation of architecture with the advantage of stability. The lung neuroendocrine tumor classification is far from being consensual, especially for lesions which don't fall in with typical carcinoid and small cell carcinoma groups. By comparing architectural models of 20 neuroendocrine tumors of the lung, this work supports the morphologic spectrum concept of these tumors and also supports the recently proposed concept of large-cell neuroendocrine tumors of the lung. Finally, architectural parameters separate small-cell-lung carcinomas from neuroendocrine non-small-cell lung carcinomas.

Carcinoid Tumor↗
PubMed1994

Pattern formation in the developing superior colliculus: ontogeny of the periodic architecture in the intermediate layers.

The superior colliculus of mammals contains a striking neurochemical architecture in which histochemically identifiable compartments are distributed in an iterative arrangement in the intermediate layers. We used stains for acetylcholinesterase activity as a compartment marker to trace ontogenesis of this architecture during pre- and postnatal development in the domestic cat. We found that compartmentation in the intermediate collicular layers is virtually absent at birth, and only gradually emerges during the first weeks of postnatal life. Over the same postnatal period, acetylcholinesterase activity shifts from a predominantly perikaryal expression pattern immediately postnatally to a nearly exclusive localization in the neuropil at maturity. Remarkably, a striking compartmentation of the superior colliculus was readily apparent with acetylcholinesterase histochemistry prenatally. The first appearance of a periodic architecture in the superior colliculus was observed at embryonic day 34, a time at which the collicular plate had not yet become laminated. The compartments characterized by high levels of acetylcholinesterase activity then gained in prominence until late in the prenatal period, when they receded and disappeared. The loss of the acetylcholinesterase-positive compartments in the perinatal period did not reflect a loss of compartmentation altogether. Neonatally, there was a distinct compartmental architecture visible with enkephalin immunohistochemistry. The virtual absence of acetylcholinesterase-positive compartments in the superior colliculus at birth therefore reflects developmental regulation of enzyme expression in the compartments, not regulation of the compartments as structural entities. We conclude that the periodic architecture, which characterizes the intermediate collicular layers in the adult cat, arises early in ontogenesis. These observations raise the possibility that the histochemical compartments are ontogenetic units that undergo remodeling as the superior colliculus matures.

Acetylcholinesterase↗