Longitudinal Compartments Research Articles

Associative learning drives longitudinally graded presynaptic plasticity of neurotransmitter release along axonal compartments.

Anatomical and physiological compartmentalization of neurons is a mechanism to increase the computational capacity of a circuit, and a major question is what role axonal compartmentalization plays. Axonal compartmentalization may enable localized, presynaptic plasticity to alter neuronal output in a flexible, experience-dependent manner. Here, we show that olfactory learning generates compartmentalized, bidirectional plasticity of acetylcholine release that varies across the longitudinal compartments of Drosophila mushroom body (MB) axons. The directionality of the learning-induced plasticity depends on the valence of the learning event (aversive vs. appetitive), varies linearly across proximal to distal compartments following appetitive conditioning, and correlates with learning-induced changes in downstream mushroom body output neurons (MBONs) that modulate behavioral action selection. Potentiation of acetylcholine release was dependent on the CaV2.1 calcium channel subunit cacophony. In addition, contrast between the positive conditioned stimulus and other odors required the inositol triphosphate receptor, which maintained responsivity to odors upon repeated presentations, preventing adaptation. Downstream from the MB, a set of MBONs that receive their input from the γ3 MB compartment were required for normal appetitive learning, suggesting that they represent a key node through which reward learning influences decision-making. These data demonstrate that learning drives valence-correlated, compartmentalized, bidirectional potentiation, and depression of synaptic neurotransmitter release, which rely on distinct mechanisms and are distributed across axonal compartments in a learning circuit.

Reorganization of longitudinal compartments in the laterally protruding paraflocculus of the postnatal mouse cerebellum.

The paraflocculus and the neighboring smaller flocculus form a remarkable protrusion in the ventrolateral aspect of the mouse cerebellum, in which the longitudinal compartments are conspicuously oriented perpendicularly to the sagittal plane. The developmental process of such anatomical arrangements in these lobules has not been fully clarified. Here, we used the genetic tractability of pcdh10-lacZ knock-in (OL-KO), IP 3 R1-nls-lacZ transgenic (1NM13) and Gpr26cre-Ai9-AldocV mice to track the development of compartments and examined local longitudinal orientation of Purkinje cells within the paraflocculus and flocculus. We observed a distinct pcdh10-positive (pcdh10+) compartment in the flocculus, whereas the paraflocculus and other lobules had a continuous paravermal pcdh10+ compartment, in the embryonic OL-KO cerebellum. During the first postnatal week, the parafloccular pcdh10+ compartment shifted laterally to the most lateral edge in the caudal part of the protruding paraflocculus. Although the most medial edge of the parafloccular pcdh10+ compartment remained in the nonprotruding part of the paraflocculus, it was disrupted from the originally continuous pcdh10+ compartment in the copula pyramidis. The local longitudinal orientation changed gradually along with the mediolateral extent of the copula pyramidis, almost becoming perpendicular to the sagittal plane in the laterally connected paraflocculus in the adult cerebellum. This rotational change in orientation was derived from the short U-shaped embryonic cerebellum, in which the surfaces of the flocculus and paraflocculus were oriented laterally. These results indicated that the peculiar compartmental organization of the paraflocculus originates from the embryonic common hemispheric compartmental organization and shaped by the significant reorganization process in the first postnatal week.

The entire trajectories of single pontocerebellar axons and their lobular and longitudinal terminal distribution patterns in multiple aldolase C-positive compartments of the rat cerebellar cortex.

The mammalian cerebellar cortex is compartmentalized, both anatomically and histochemically, into multiple parasagittal bands. To characterize the multiple zonal patterns of pontocerebellar mossy fiber projection, single neurons in the basilar pontine nucleus (BPN) were labeled by injecting biotinylated dextran amine into the BPN, and the entire axonal trajectory of single labeled neurons (n = 25) was reconstructed in relation to aldolase C compartments of Purkinje cells in rats. Single pontocerebellar axons, after passing through the contralateral middle cerebellar peduncle, ran transversely in the deep cerebellar white matter toward and often across the midline, and on their ways, gave rise to 2-10 primary collaterals at almost right angles in specific lobules only contralaterally or bilaterally with contralateral predominance. Each primary collateral further branched in a parasagittal plane to form a strip-shaped longitudinal termination zone with rosette-type swellings clustered in aldolase C-positive compartments in a single or multiple lobules, mainly in compartment 4+//5+, 5+//6+, and 6+//7+. Axons arising from the central, rostral, and lateral part of the BPN projected with multiple branches, mainly to simple lobule, crus II and paramedian lobule, to crus I and dorsal paraflocculus, and to ventral paraflocculus and lobule IXc, respectively. The results showed the pontocerebellar projection is closely related to lobular and compartmental organization of the cerebellum. A comparison of single axon morphologies of different mossy fiber systems indicates that the projection pattern of single pontocerebellar neurons with multiple collaterals innervating different longitudinal compartments arranged in a mediolateral direction represents a general feature of mossy fiber projection.

Clustered Fine Compartmentalization of the Mouse Embryonic Cerebellar Cortex and Its Rearrangement into the Postnatal Striped Configuration

Compartmentalization is essential for a brain area to be involved in different functions through topographic afferent and efferent connections that reflect this organization. The adult cerebellar cortex is compartmentalized into longitudinal stripes, in which Purkinje cells (PCs) have compartment-specific molecular expression profiles. How these compartments form during development is generally not understood. To investigate this process, we focused on the late developmental stages of the cerebellar compartmentalization that occur from embryonic day 17.5 (E17.5), when embryonic compartmentalization is evidently observed, to postnatal day 6 (P6), when adult-type compartmentalization begins to be established. The transformation between these compartmentalization patterns was analyzed by mapping expression patterns of several key molecular markers in serial cerebellar sections in the mouse. A complete set of 54 clustered PC subsets, which had different expression profiles of FoxP2, PLCβ4, EphA4, Pcdh10, and a reporter molecule of the 1NM13 transgenic mouse strain, were distinguished in three-dimensional space in the E17.5 cerebellum. Following individual PC subsets during development indicated that these subsets were rearranged from a clustered and multilayered configuration to a flattened, single-layered and striped configuration by means of transverse slide, longitudinal split, or transverse twist spatial transformations during development. The Purkinje cell-free spaces that exist between clusters at E17.5 become granule cell raphes that separate striped compartments at P6. The results indicate that the ∼50 PC clusters of the embryonic cerebellum will ultimately become the longitudinal compartments of the adult cerebellum after undergoing various peri- and postnatal transformations that alter their relative spatial relationships.

Improved Penile Histology by Phalloidin Stain: Circular and Longitudinal Cavernous Smooth Muscles, Dual-endothelium Arteries, and Erectile Dysfunction-associated Changes

To investigate whether fluorochrome-conjugated phalloidin can delineate cavernous smooth muscle (CSM) cells and whether it can be combined with immunofluorescence (IF) staining to quantify erectile dysfunction (ED)-associated changes. ED was induced by cavernous nerve crush in rats. Penile tissues of control and ED rats were stained with Alexa-488-conjugated phalloidin and/or with antibodies against rat endothelial cell antigen (RECA), CD31, neuronal nitric oxide synthase (nNOS), and collagen-IV (Col-IV). Phalloidin was able to delineate CSM as composed of a circular and a longitudinal compartment. When combined with IF stain for CD31 or RECA, it helped the identification of the helicine arteries as covered by endothelial cells on both sides of the smooth muscle layer. When combined with IF stain for nNOS, it helped the identification that nNOS-positive nerves were primarily localized within the dorsal nerves and in the adventitia of dorsal arteries. When combined with IF stain for Col-IV, it helped identify that Col-IV was localized around smooth muscles and beneath the endothelium. Phalloidin also facilitated the quantitative analysis of ED-related changes in the penis. In rats with cavernous nerve injury, RECA or Col-IV expression did not change significantly, but CSM and nNOS nerve contents decreased significantly. Phalloidin stain improved penile histology, enabling the visualization of the circular and longitudinal compartments in the CSM. It also worked synergistically with IF stain, permitting the visualization of the dual endothelial covering in helicine arteries, and facilitating the quantification of ED-related histologic changes.

Close correlation between the birth date of purkinje cells and the longitudinal compartmentalization of the mouse adult cerebellum

The adult cerebellum is organized into longitudinal compartments that are revealed by specific axonal projections (olivocerebellar and corticonuclear projections). These compartments in the adult cerebellum are closely correlated with the striped expression of zebrin II (aldolase C), a late-onset marker of Purkinje cells. Similarly, the embryonic cerebellum is organized into longitudinal compartments that are revealed by striped expression of other genes (early-onset markers). The cerebellar compartments are thought to be the basic and functional subdivisions of the cerebellum. However, the relationship between the embryonic (early-onset) and the adult (late-onset) compartments has remained unknown, because the pattern of the embryonic compartments is distinct from that of the adult compartments. To examine this issue, we labeled Purkinje cells (PCs) born at embryonic day (E) 10.5, E11.5, and E12.5 by using an adenoviral vector and traced their fated positions in the adult cerebellum. By comparing the striped distribution of each cohort of birth date-related PCs with the striped pattern of zebrin II immunoreactivity (zebrin II bands) in the entire adult cerebellum, we found that the striped distribution of PCs correlated strikingly with zebrin II bands. Generally, a single early-onset compartment was transformed directly into a single late-onset compartment. Therefore, our observation also indicated the close correlation between the compartments formed by birth date-related PCs and olivocerebellar projections. Furthermore, we found that the cerebellum was composed of three units showing lateral-to-medial developmental gradients, as revealed by the birth dates of PCs. The results suggest that PC birth dates play an important role in organizing cerebellar compartmentalization.

Limiting factors for phytoplankton growth in subtropical reservoirs: the effect of light and nutrient availability in different longitudinal compartments

Limited information is available on the interactions between environmental factors and algal growth in tropical and subtropical aquatic systems. We investigated the relationships between algal biomass (measured as chlorophyll, Chl-a) and light, total phosphorus (TP) and total nitrogen (TN) in longitudinal zones of subtropical reservoirs. We studied the seasonal variation of water variables in Itupararanga Reservoir (Brazil) and compared the results with 16 other subtropical lakes and reservoirs. The longitudinal zones in Itupararanga Reservoir were considered statistically different (p < 0.05, MANOVA). From the riverine zone to the dam region of the reservoir, Spearman Correlation Test suggested that light limitation and TP limitation tended to decrease and increase, respectively. Although nitrate concentrations were high (>400 μg/L), the Spearman coefficients between Chl-a and TN and the TN:TP ratios (11:1 < TN:TP < 35:1) indicated that nitrogen may be co-limiting algal growth in the studied water body. Putting Itupararanga in a regional context allowed assessment of potential influences of land use on trophic state. Within the subtropical dataset, TP explained a greater percentage of variance in Chl-a (R2 = 0.70) than TN (R2 = 0.17). The main land use type within the reservoirs drainage area significantly influenced the concentrations of TP, TN, and Chl-a (p < 0.05, MANOVA), with different relationships between nutrients and chlorophyll in forested (R2 = 0.12–0.33), agricultural (R2 = 0.50–0.68) and urban (R2 = 0.09–0.64) watersheds. Comparisons with literature values and those from reservoirs with less altered watersheds indicated that Itupararanga Reservoir is reaching the mesotrophic–eutrophic boundary, and further nutrient enrichment could cause water quality degradation.

Compartmentalization of the Deep Cerebellar Nuclei Based on Afferent Projections and Aldolase C Expression

The distribution of aldolase C (zebrin II)-positive and -negative Purkinje cells (PCs) can be used to define about 20 longitudinally extended compartments in the cerebellar cortex of the rat, which may correspond to certain aspects of cerebellar functional localization. An equivalent compartmental organization may exist in the deep cerebellar nuclei (DCN). This DCN compartmentalization is primarily represented by the afferent projection pattern in the DCN. PC projections and collateral nuclear projections of olivocerebellar climbing fiber axons have a relatively localized terminal arbor in the DCN. Projections of these axons make a closed olivo-cortico-nuclear circuit to connect a longitudinal stripe-shaped cortical compartment to a small subarea in the DCN, which can be defined as a DCN compartment. The actual DCN compartmentalization, which has been revealed by systematically mapping these projections, is quite different from the cortical compartmentalization. The stripe-shaped alternation of aldolase C-positive and -negative narrow longitudinal compartments in the cerebellar cortex is transformed to the separate clustering of positive and negative compartments in the caudoventral and rostrodorsal DCN, respectively. The distinctive projection of aldolase C-positive and -negative PCs to the caudoventral and rostrodorsal DCN underlies this transformation. Accordingly, the medial cerebellar nucleus is divided into the rostrodorsal aldolase C-negative and caudoventral aldolase C-positive parts. The anterior and posterior interposed nuclei generally correspond to the aldolase C-negative and -positive parts, respectively. DCN compartmentalization is important for understanding functional localization in the DCN since it is speculated that aldolase C-positive and -negative compartments are generally associated with somatosensory and other functions, respectively.

SIMDOT-AbMe: Microphysiologically Based Simulation Tool for Quantitative Prediction of Systemic and Local Bioavailability of Targeted Oral Delivery Formulations

The purpose of this study was to develop a physiologically based simulation tool that is able to predict local as well as systemic bioavailability of 5-aminosalicylic acid (5-ASA)-targeted delivery formulations using the existing understanding of the transport and metabolism mechanisms of 5-ASA. The model accounts for active and passive transcellular transport (absorptive and efflux), passive paracellular transport, intestinal biotransformation, and systemic metabolism and clearance. The intestinal physiology was represented by transverse segments for ileum and proximal colon and longitudinal compartments for the microphysiology of the intestinal tissue. The tool, equipped with an optimization routine that enables tuning model parameters, was developed in Matlab and uses a user-friendly graphical interface for data input and output. Physiologic and kinetic model parameters were estimated either from literature monolayer transport studies using nonlinear curve fitting or obtained directly from the literature. 5-ASA clinical pharmacokinetic profiles of a once-daily (one 4-g/day dose) and twice-daily (two 2-g/day doses) dosing regimen were used to partially calibrate and validate the model, respectively. Simulation results showed that drug C(max) in the gut mucosal layers reached a higher level and was achieved sooner than in the systemic blood level. The computed relative local bioavailability with respect to the systemic bioavailability was 0.063. With use of the model, the relative local bioavailability of different formulations can be established for fast performance verification of new preparations based on measured systemic bioavailability. These types of models play a critical role in designing such preparations and rapidly assessing their effectiveness and will foster efficient experimental designs, saving time and resources.

Subcellular redistribution of calponin underlies sustained vascular contractility following traumatic brain injury

Objectives: The purpose of this study was to observe temporal changes in calponin (Cp), a contractile protein, in response to traumatic brain injury (TBI).Methods: Double immunocytochemistry in conjunction with morphometric methods was used to study Cp temporal migration in smooth muscle cells (SM) of reacting microvessels following TBI, as induced using a weight-drop, acceleration impact method.Results: Quantification of migrated Cp in the SM wall after TBI was carried out on three-dimensional orthographic reconstructions of serial, digitally acquired images and optical densitometry. Color shifts in Cp intensity were measured in three arbitrary longitudinal compartments, luminal (lu), middle (m) and abluminal (ablu), of SM cytoplasm with respect to proximity to the vessel's lumen. By 24 and 48 hours after TBI, most Cp had migrated from the SM compartment closest to the lu to that farthest away or ablu. In addition, a qualitative increase in Cp was detected closest to the ablu compartment in those segments of the vessel severely constricted.Discussion: Cp migration from cytoskeletal to contractile regions of SM supports its role both in the initiation of vessel contractility and its interaction with cytoskeletal structures subjacent to the cell membrane in SM's contracted state.

Relationship of complex spike synchrony bands and climbing fiber projection determined by reference to aldolase C compartments in crus IIa of the rat cerebellar cortex

Synchronous complex spike (CS) activity occurs most often among cerebellar Purkinje cells located in a narrow longitudinal (parasagittal) strip of cortex (synchrony band). The relationship of the anatomical organization of the olivocerebellar projection to these synchrony bands has not been investigated in detail. Thus, we studied this relationship by using the aldolase C (zebrin II) expression pattern, another landmark for the cerebellar longitudinal organization, as a reference frame in rat crus IIa. Crus IIa consists of 10 aldolase C-positive and -negative longitudinal compartments. Aldolase C labeling after multiple-electrode recording of CSs indicated that in lateral crus IIa (compartments 5+ to 7+) synchrony bands were generally constrained to single compartments. In contrast, in medial crus IIa (compartments 4a- to 5a-) the synchrony within and across the compartments was much higher than in lateral crus IIa, resulting in wide synchrony bands covering multiple compartments. Retrograde labeling of olivary neurons by injections of biotinylated dextran amine into aldolase C compartments in crus IIa showed that compartments in medial crus IIa were all innervated by the caudal part of the medial accessory olive. On the other hand, each aldolase C compartment in the lateral crus IIa was innervated by a region in a different subnucleus in the rostral inferior olive. These regions in different subnuclei were located close to each other. These results suggest that CS synchrony bands reflect the olivocerebellar compartmental projection pattern and neuronal coupling within a particular olivary subnucleus, and that medial and lateral crus IIa may be functionally distinct.

Effect of Longitudinal Bulkheads on Damage Stability of Model RO/RO Ferries

The paper reports on experimental investigations which have been made on three model RO/RO ferries. One of these was based on a 1/100th scale model of the Herald of Free Enterprise ferry. The other models were modified versions of the Herald of Free Enterprise which were so modified that they did not decrease the efficient concept of the throughput of a conventional vessel. One modified model had nine longitudinal compartments, while another had six longitudinal compartments; these vessels should meet SOLAS90+50 regulations. The RO/RO ferry models with nine and six compartments had considerably better damage stability characteristics than the conventional model. The experiments were carried out on all models without the consideration of waves and wind. Small weights were placed on the model ferries, to represent motor vehicles, and water was added on the car deck. Measurements of the resulting heel angles were taken. All results were plotted on graphs and they were compared and discussed. The effect of cargo shift on the transverse damage stability of these vessels was found to be significant. The paper also contains a brief history of a few very important RO/RO ferry accidents that have taken place since the end of the Second World War.

Topical treatment of digital dermatitis associated with severe heel-horn erosion in a Swedish dairy herd

Two experiments were run in a commercial dairy herd to test the efficacy of topical treatments of digital dermatitis associated with severe heel-horn erosion. In Experiment I, topical treatments with solutions of either glutaraldehyde or oxytetracycline were compared with foot trimming and cleansing alone. After trimming of all feet, one front and one rear foot in each cow were treated with either glutaraldehyde or oxytetracycline (regardless of dermatitis status), while the other feet were used as controls and only trimmed. Two hundred foot records were obtained from 34 Swedish Red and White and 16 Swedish Holstein cows. The proportions ( p) of feet cured from digital dermatitis were compared between each group of medically treated feet and the control feet, assuming the feet to be independent observations with respect to curing. Oxytetracycline was significantly more effective than hoof trimming alone ( p=0.87 and 0.34, respectively; P<0.001) and than glutaraldehyde ( p=0.41; P=0.004). Treatment with glutaraldehyde was no more effective than hoof trimming alone. In Experiment II, a specially designed footbath with two longitudinal compartments was used to study the effectiveness of a solution of acidic ionised copper in preventing or curing digital dermatitis. The footbath—using water in one compartment—was constructed to make within-cow comparisons of treatment efficacy possible. The hoof health of 44 dairy cows (also included in Experiment I) were studied when the animals first were turned out to pasture and at the end of the grazing season (approximately 6 months later). During the grazing season, the cows were walked through the footbath twice daily after milking for a total of 47 days, divided into five separate periods ranging in length from 3 to 16 days. As judged by a two-sample comparison of proportions, a higher proportion of the cows’ hind feet that were affected by dermatitis were cured by the copper solution (20/24) than by water alone (12/23). The copper solution had no significant preventive effect on healthy feet.

Importance of the predator's ecological neighborhood in modeling predation on migrating prey

Most mathematical descriptions of predator‐prey interactions fail to take into account the spatio‐temporal structures of the populations, which can lead to errors or misinterpretations. For example, a compact pulse of prey migrating through a field of quasi‐stationary predators may not be well described by standard predator‐prey models, because the predators and prey are unlikely to be well mixed; that is, the prey may be exposed to only a fraction of the predator population at a time. This underscores the importance of properly accounting for the ecological neighborhood, or effective feeding range, of predators in models. We illustrate this situation with a series of models of salmon smolts migrating through a reservoir arrayed with predators. The reservoir is divided into a number of longitudinal compartments or spatial cells, the length of each cell representing the upstream‐downstream range over which predators can forage. In this series of models a 100‐km‐long reservoir is divided, successively into 2, 5, 10, 25, 50, 100, 200, and 400 cells, with respective cell lengths of 50, 20, 10, 4, 2, 1, 0.5, and 0.25 km. We used a detailed individual‐based simulation model at first, but to ensure robustness of results we supplemented this with a simple analytic model. Both models showed sharp differences in the predicted mortality to a compact pulse of smolt prey moving through the reservoir, depending on the number of spatial cells in the model. In particular, models with fewer than about 10 cells vastly overpredicted the amount of mortality due to predators with activity ranges of not more than a few kilometers. These results corroborate recent theoretical and simulation studies on the importance of spatial scale and behavior in modeling predator‐prey dynamics.

Pattern of cell kinetics in colorectal mucosa of patients with different types of adenomatous polyps of the large bowel

It is generally accepted that adenomatous polyps represent the natural precursor of many colorectal malignancies. The sequence, however, which leads from a normally appearing mucosa to cancer is complex and involves many steps, including a hyperproliferative mucosa with an upward expansion of the replicative compartment. The current study evaluates cell replication in normal colorectal mucosa of patients with adenomatous polyps of various types and relates the observed findings to the main clinical and morphologic features of adenomas. Forty-four patients with polyps and 27 controls entered the study. Samples of colorectal mucosa were taken at endoscopy and cell replication was evaluated with a standard autoradiographic procedure. Cell replication was expressed as labeling index (LI), in the whole crypt and in each of the five longitudinal compartments in which the crypts were divided. Total LI and LI per crypt compartment were significantly higher (P less than 0.02 and P less than 0.01, respectively) than in controls. There was no appreciable difference of LI values between patients with single or multiple, tubular or tubulovillous, small or large adenomas, but in all of these subgroups LI was significantly higher than in controls. In conclusion, in normally appearing colorectal mucosa of patients with adenomatous polyps there was a significant increase of cell replication and a marked upward expansion of the proliferative zone; these changes were more evident in the left colon and in the rectum. Finally, cell replication did not seem to be related to the number of polyps, to the most common histotypes, or to the pattern of recurrence.

Late cytokinetic abnormalities in irradiated reactal mucosa

Late cytokinetic changes of the colonic crypt epithelium after radiation therapy were investigated. A monoclonal antibody to bromodeoxyuridine (anti-BrdU MAb) was used in tissue specimens previously incubated with BrdU to show S-phase cells by immunohistochemical technique. Endoscopic rectal biopsies were taken from 30 patients previously treated with radiotherapy for gynaecological cancer and from 50 patients with comparable but untreated neoplasms, as controls. Number and height distribution of S-phase cells were evaluated by dividing each crypt column into 5 equal longitudinal compartments. No statistically significant differences were found in total Labelling Index (LI) between controls and irradiated mucosa, whereas LI per crypt compartment, percentage of labelled compartments and percentage of BrdU-positive cells in the middle and superficial portions of the crypt were significantly higher in patients submitted to radiation therapy. This kinetic abnormality corresponds to a progressive shift of the major zone of DNA synthesis to the upper third of the crypt as a late reaction to radiation and represents an early step in the histogenesis of colorectal cancer. These results lend support to the view that there is a higher risk of colorectal carcinoma after pelvic irradiation.

The influence of age on colonic epithelial cell proliferation.

Cancer of the large bowel is relatively rare in persons younger than 50 years of age, but its incidence increases sharply in persons older than 60 years of age. We thought that the evaluation of colonic cell proliferation, an accurate biomarker of predisposition to colorectal cancer, might help to elucidate the susceptibility of elderly persons to this common malignancy. Accordingly, 30 persons with normal lower endoscopy results were divided into three age groups (30 to 50,51 to 65, and 66 to 90 years of age; Groups 1, 2, and 3, respectively). Samples of rectal mucosa were taken at endoscopic examination, incubated with [3H]thymidine, and processed with standard autoradiographic techniques. At histologic examination, each intestinal hemicrypt was divided into five equal longitudinal compartments from the fundus (compartment 1) to the surface (compartment 5). The number and the position of labeled cells along the crypt were recorded. The total labeling index (LI) (the ratio of labeled cells to total cells) was significantly higher in Group 3 than in the two other groups. Similarly, the LI per crypt compartment in the most superficial portions of the crypts was consistently higher in persons older than 65 years of age (P less than 0.01 at least), indicating an expansion of the proliferative zone to the most superficial portion of the colonic glands. When the proliferative profiles of the three groups of subjects investigated were compared with those of patients with polyps, an almost complete overlap of values was observed between this population at increased risk for cancer and the subjects in Group 3. We conclude that aging is characterized by an overall increase of epithelial cell proliferation in colorectal mucosa and by an upwards expansion of the proliferative compartment, similar to that observed in a population at risk for cancer of the large bowel.

Segment-related, mosaic neurogenetic pattern in the forebrain and mesencephalon of early chick embryos: I. Topography of AChE-positive neuroblasts up to stage HH18.

Histochemical mapping of AChE-positive neuroblasts in sectioned and whole-mounted preparations of the chick embryo mesencephalon and prosencephalon allows a correlation of early neural tube morphogenesis (segmentation, longitudinal compartmentation) with the heterochronic pattern of neurogenesis. One significant finding is that the initial appearance of neuroblasts in the forebrain does not follow neuromeric segmentation, but evolves in parallel with it. Early neuroblasts appear as separate, distinct groups within specific matrix territories at the center of the transverse neuromeric segments. Neighbouring segments display different spatiotemporal patterns of neurogenesis. Overall gradients of differentiation in the rostrocaudal and ventrodorsal directions are absent, whereas a clear-cut segment-related, mosaic pattern becomes evident. Notwithstanding this, gross regularities of heterochrony in the neurogenetic behavior of the different segments lead to a definition of elemental longitudinal compartments of the forebrain and mesencephalon (floor, paramedian, basal, and alar regions) on the basis of precocious differentiation of the basal region and retarded differentiation of the paramedian and alar regions.

Chemoarchitectonic zonation of the monkey cerebellum

The modular organization of the monkey cerebellum is revealed in normal material by histochemical methods for demonstrating the presence of the enzymes acetylcholinesterase (AChE) and cytochrome oxidase (CO). In the cerebellar white matter, AChE- and CO-rich fibers are distributed in longitudinal compartments, which are aligned with AChE- and CO-rich bands in the granule cell layer, and with narrower AChE-rich strips in the molecular layer. The number and disposition of zones demonstrated histochemically are consistent with, and extend, the basic scheme of cerebellar zonation established by Voogd and Voogd and Bigare´.

Influence of matric potentials on carpogenic germination of sclerotia ofSclerotinia sclerotiorum. I. Development of an inclined box technique to observe apothecium production

A 4.1-m-long inclined box with five longitudinal compartments was filled with fine sandy loam and distilled water was added at the lower end. Due to capillary rise, steady state saturated and unsaturated flow of soil water, vapor movement in the soil atmosphere, and a controlled steady rate of evaporation from the soil surface, constant soil matric potentials between 0 and -15 bars were obtained in the box. The angle of inclination was reduced above the middle of the box to fit the moisture characteristic curve of the fine sandy loam. After soil moisture had reached equilibrium, sclerotia of Sclerotinia sclerotiorum pre-treated at -15 bars for 1 month at 5°C and non-pretreated sclerotia were placed at 2 cm intervals on the surface of the soil and at 1 cm depth. At about 15°C germination started after 2 weeks. There was no interaction between matric potential and speed of germination. The largest number of apothecia was produced near field capacity (-0.11 to -0.40 bar). However, apothecia developed between...