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Results for “spatial patterning”

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PubMed2003

Changes in the spatial pattern of low birth weight in a southern California county: the role of individual and neighborhood level factors.

Individual-level maternal risk factors have been able to explain only a small proportion of low birth weight (LBW) births in the US to date and neighborhood-level factors have not been recognized as important predictors of reproductive outcomes. At the US/Mexico border, tremendous demographic changes have taken place between 1980 and 1990. Whether high population growth, economic pressures, and community instability have affected reproductive health in this region is not known. We used spatial epidemiologic methods to investigate the importance of changes in neighborhood and individual-level risk factors in predicting changes in two measures of adverse reproductive health: term and preterm LBW. Using approximately 16,000 births in 1980 and 24,000 births in 1990, we produced a continuous surface of LBW change (Z scores for difference in proportions) for southern San Diego County, CA, and identified statistically significant "hot spots" of elevated risk. Using a geographic information system, data from the 1980 and 1990 US Census were smoothed to link neighborhood-level variables with individual-level data from the 1980 and 1990 California birth certificates. Multivariate regression models were developed to identify individual- and neighborhood-level variables of 1980-1990 changes which were predictive of Z scores of LBW change. Results of conditional autoregressive models were used to assess effects of spatial autocorrelation. The continuous surface of LBW identified areas with statistically significant increases (17 areas for term LBW and 14 areas for preterm LBW). While individual- and neighborhood-level variables explained about an equal amount of variance in term LBW, only neighborhood-level variables were significant predictors of preterm LBW. While changes in maternal race/ethnicity composition and a measure of stability were related to term LBW, measures of affluence were related to preterm LBW. This study highlights the importance of socioeconomic and demographic changes in a woman's neighborhood on reproductive health.

Adult↗

PubMed2003

The spatial pattern of response magnitude and selectivity for orientation and direction in cat visual cortex.

Optical imaging studies of orientation and direction preference in visual cortex have typically used vector averaging to obtain angle and magnitude maps. This method has shown half-rotation orientation singularities (pinwheels) located within regions of low orientation vector magnitude. Direction preference is generally orthogonal to orientation preference, but often deviates from this, particularly in regions of low direction vector magnitude. Linear regions of rapid change in direction preference terminate in or near orientation singularities. The vector-averaging method is problematic however because it does not clearly disambiguate spatial variation in orientation tuning width from variation in height. It may also wrongly estimate preferred direction in regions where preference is weak. In this paper we analyze optical maps of cat visual cortex by fitting model tuning functions to the responses. This new method reveals features not previously evident. Orientation tuning height and width vary independently across the map: tuning height is always low near singularities, however regions of broad and narrow orientation tuning width can be found in regions of low tuning height, often alternating in a spoke-like fashion around singularities. Orientation and direction preference angles are always closely orthogonal. Reversals in direction preference form lines that originate precisely in orientation singularities.

Animals↗

PubMed2001

A force-plate actometer for quantitating rodent behaviors: illustrative data on locomotion, rotation, spatial patterning, stereotypies, and tremor.

This report describes a new kind of actometer for recording the behavior of rodents or other small animals. The instrument, a force-plate actometer, uses a stiff, low-mass horizontal plate coupled to four supporting force transducers positioned at the corners of the plate. When an animal moves on the plate, its movements are sensed by the transducers whose signals are processed by computer to yield measurements of a wide range of behaviors or behavioral attributes, such as locomotor activity, rotation around the center, whole-body tremor, and amphetamine-induced stereotypies. Spatial resolution is less than 1 mm, and temporal resolution is 0.02 s. Sample data were presented comparing the locomotor activity of CD-1, BALB/c, and C57BL/6 mice before and after treatment with D-amphetamine sulfate. Rotational behavior was recorded in an amphetamine-treated rat that had sustained a unilateral 6-hydroxydopamine-induced lesion of the nigrostriatal system. In the C57BL/6 mouse, harmaline-induced tremor was quantified. With rats as subjects, the force-plate actometer was used to quantify amphetamine-induced stereotypies, to demonstrate the development of sensitization to amphetamine's effects, and to quantitate the consistent 11-12 Hz rhythmicities that underlie the sterotypies. The performance of the force-plate actometer was compared with that of a variety of instruments reported in the literature on behavioral instrumentation. Finally, potential applications in neuroscience research other than those illustrated in this report were discussed.

Amphetamine↗

PubMed2001

Temporal and spatial patterns of DNA fragmentation following focally or systemically-evoked status epilepticus in rats.

Status epilepticus (SE) triggers neuronal degeneration comprised of both necrotic and apoptotic components. Here we determined whether internucleosomal DNA fragmentation reflects the severity of SE-induced neuronal damage. We utilized both a systemic (kainic acid) and a focally-induced model of SE in rats. DNA fragmentation was analyzed in rhinal cortex and hippocampus at various time points following SE episodes of varying durations (30-120 min). Radioactively labeled DNA fragments were analyzed by agarose gel electrophoresis and quantified by liquid scintillation counting. The spatial and temporal characteristics of the SE-evoked DNA fragmentation indicated that this marker of apoptosis appears as early as 8 h after SE and reaches peak expression at 48 h. This method permitted us to quantitatively monitor the evolution of the apoptotic component of cell death over the acute post-injury period (8-72 h). Moreover, in both models of SE, the DNA fragmentation varied directly as a linear function of the duration of SE between 30 and 120 min suggesting that this marker should be highly responsive to neuroprotective intervention.

Animals↗

PubMed1997

Light modulates the spatial patterns of 3-hydroxy-3-methylglutaryl coenzyme A reductase gene expression in Arabidopsis thaliana.

Although the coordinated biosynthesis of isoprenoid compounds is thought to be essential to the normal processes of plant growth and development, the mechanisms that regulate the mevalonate pathway in plants are not well understood. As the first committed step in the pathway, the conversion of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) to mevalonic acid by HMG CoA reductase and the regulation of the genes encoding this enzyme have been implicated in the network that controls isoprenoid biosynthesis in higher plants. Using histochemical staining for beta-glucuronidase, as well as conventional RNA hybridization analysis, the temporal and spatial regulation of HMG1, one of the genes encoding HMG CoA reductase in the crucifer Arabidopsis thaliana, has been characterized. Furthermore, the HMG1 promoter is shown to be differentially responsive to illumination in different organs, and promoter activation by light deprivation is confined primarily to immature leaves. In contrast, expression of the HMG1 gene in roots is confined to the elongation zone and is not responsive to illumination. Light-mediated regulation of HMG1 expression is shown to be an organ-autonomous response that depends on direct illumination, and environmental cues regarding light do not appear to be exchanged between different organs in Arabidopsis. These studies reveal several new features of HMG1 regulation, and indicate that the high levels of HMG CoA reductase expression detected in immature leaves may be primarily attributed to the dark-induced expression of HMG1, and that HMG1 is expressed at low levels throughout the plant in response to light. Thus, environmental cues interact with the developmental program to define the pattern of HMG1 gene expression in Arabidopsis.

Arabidopsis↗

PubMed1999

Exploring spatial patterns of mortality: the new atlas of United States mortality.

The National Center for Health Statistics, CDC, has produced an Atlas of United States Mortality which includes maps of rates for the leading causes of death in the United States for the period 1988-1992. As part of this project, many aspects of statistical mapping have been re-examined to maximize the atlas's effectiveness in conveying accurate mortality patterns to epidemiologists and public health practitioners. Because recent cognitive research demonstrated that no one map style is optimal for answering many different map questions, maps and graphs of several different mortality statistics are included for each cause of death. New mixed effects models were developed to provide predicted rates and improved variance estimates. Results from these models were smoothed using a weighted head-banging algorithm to produce maps of general spatial trends free of background noise. Maps of White female lung cancer rates from the new atlas are presented here to illustrate how this innovative combination of maps and graphs permits greater exploration of the underlying mortality data than is possible from previous single-map atlas designs. Published in 1999 by John Wiley & Sons, Ltd. This article is a U.S. Government work and is in the public domain in the United States.

Adult↗

PubMed1995

Developmental changes in the distribution of the endoplasmic reticulum and inositol 1,4,5-trisphosphate receptors and the spatial pattern of Ca2+ release during maturation of hamster oocytes.

During maturation of hamster oocytes, the distribution of the endoplasmic reticulum (ER) and inositol 1,4,5-trisphosphate receptors (InsP3Rs) was found to change dramatically, as observed using confocal microscopy with DiI and electron microscopy for the ER and immunohistochemistry for InsP3Rs. In immature oocytes at the germinal vesicle (GV) stage, ER and InsP3Rs were located predominantly in several large masses near the surface and also in the perinuclear region near the surface. In contrast, fine ER networks and low-density InsP3Rs were present in the inner cytoplasm. The ER appeared to be formed as vesicles from annulate lamellae (AL) in the subcortical area. Rises in Ca2+ concentration occurred in the cytoplasm and the GV when immature oocytes were inseminated, but clear Ca2+ waves did not occur. Ca2+ rises began preferentially from the perinuclear region in response to low doses of serotonin or to uniform stimulation of InsP3Rs with photocleavage of caged InsP3. Serum also induced inhomogeneous Ca2+ release, shown by nonpropagating Ca2+ rises at multiple surface sites. Between the GV stage and prometaphase I the number and size of the surface ER masses increased, and the AL disappeared. This quantitative ER maturation was followed by a second step, spatial maturation. After prometaphase I, surface ER masses gradually dispersed to a number of much smaller ER clusters near the surface and, together with the perinuclear mass, were incorporated into thicker ER networks, resulting in a reticular pattern of the ER with small patches of InsP3Rs throughout the mature egg. The ER shifted to the peripheral surface with apposition to cortical granules. These developmental changes in ER Ca2+ stores may account, at least partly, for the acquisition of the ability of an egg to undergo normal fertilization.

Animals↗

PubMed1994

Isolation of an Arabidopsis thaliana Mutant, mto1, That Overaccumulates Soluble Methionine (Temporal and Spatial Patterns of Soluble Methionine Accumulation).

We isolated Arabidopsis thaliana mutants that are resistant to ethionine, a toxic analog of methionine (Met). One of the mutants was analyzed further, and it accumulated 10- to 40-fold more soluble Met than the wild type in the aerial parts during the vegetative growth period. When the mutant plants started to flower, however, the soluble Met content in the rosette region decreased to the wild-type level, whereas that in the inflorescence apex region and in immature fruits was 5- to 8-fold higher than the wild type. These results indicate that the concentration of soluble Met is temporally and spatially regulated and suggest that soluble Met is translocated to sink organs after the onset of reproductive growth. The causal mutation, designated mto1, was a single, nuclear, semidominant mutation and mapped to chromosome 3. Accumulation profiles of soluble amino acids suggested that the mutation affects a later step(s) in the Met biosynthesis pathway. Ethylene production of the mutants was only 40% higher than the wild-type plants, indicating that ethylene production is tightly regulated at a step after Met synthesis. This mutant will be useful in studying the translocation of amino acids, as well as regulation of Met biosynthesis and other metabolic pathways related to Met.

Journal Article↗

PubMed2002

Design and constraints of the Drosophila segment polarity module: robust spatial patterning emerges from intertwined cell state switches.

The Drosophila segment polarity genes constitute the last tier in the segmentation cascade; their job is to maintain the boundaries between parasegments and provide positional "read-outs" within each parasegment for the entire developmental history of the animal. These genes constitute a relatively well-defined network with a relatively well-understood patterning task. In a previous publication (von Dassow et al. 2000. Nature 406:188-192) we showed that a computer model predicts the segment polarity network to be a robust boundary-making device. Here we elaborate those findings. First, we explore the constraints among parameters that govern the network model. Second, we test architectural variants of the core network, and show that the network tolerates a wide variety of adjustments in design. Third, we evaluate several topologically identical models that incorporate more or less molecular detail, finding that more-complex models perform noticeably better than simplified ones. Fourth, we discuss two instances in which the failure of the network model to behave in a life-like fashion highlights mechanistic details that need further experimental investigation. We conclude with an explanation of how the segment polarity network can be understood as an interwoven conspiracy of simple dynamical elements, several bistable switches and a homeostat. The robustness with which the network as a whole maintains a spatial regime of stable cell state emerges from generic dynamical properties of these simple elements.

Animals↗

PubMedDate not supplied

Spatial patterns of anthropometric variation in India with reference to geographic, climatic, ethnic and linguistic backgrounds.

BACKGROUND: Anthropometric variation can be fruitfully utilized to investigate microevolutionary processes. Anthropometric variations in the Indian subcontinent based on stature and three indices (Cephalic Index, Nasal Index, and Total Facial Index) are highly variable and discriminative among populations across geographical regions. AIMS: Anthropometric variation in stature, Cephalic Index (CI), Nasal Index (NI) and Total Facial Index (TFI) were investigated with respect to ethnic, linguistic, geographical and climatic affiliation, across the Indian subcontinent. SUBJECTS AND METHODS: Published data on anthropometric variations of 531 populations from the Indian subcontinent were analysed using discriminant analysis and spatial autocorrelation analysis. RESULTS: Discriminant analysis of the four anthropometric variables shows that stature and NI are good discriminators for populations of different languages. Stature, NI and CI discriminate well among populations of diverse ethnic origin and climatic conditions in different regions. TFI is not a good discriminator for populations of diverse ethnic, linguistic and climatic attributes. Spatial autocorrelation analysis showed significant departure from randomness, suggesting geographic structuring. The Moran's I estimate is positive and statistically significant for the four variables at low distances but exhibits significant negative association at higher values. CONCLUSION: The results suggest geographical clines for the four anthropometric variables and indicate the influence of population structure on the studied variables.

Analysis of Variance↗

PubMed1999

Use of developmental marker genes to define temporal and spatial patterns of differentiation during embryoid body formation.

Mouse embryonic stem cells are pluripotent cells that are derived from the inner cell mass of blastocysts. When induced to synchronously enter a program of differentiation in vitro, they form embryoid bodies that contain cells of the mesodermal, hematopoietic, endothelial, muscle, and neuronal lineages. Here, we used a panel of marker genes with early expression within the germ layers (oct-3, Brachyury T, Fgf-5, nodal, and GATA-4) or a variety of lineages (flk-1, Nkx-2.5, EKLF, and Msx3) to determine how progressive differentiation of embryoid bodies in culture correlated with early postimplantation development of mouse embryos. Using RNA in situ hybridization, we found that the temporal and spatial relationships existing between these marker genes in vivo were maintained also in vitro. Studying the onset of marker gene expression allowed us also to determine the time course of differentiation during the formation of embryoid bodies. Thus, stages equivalent to embryogenesis between implantation and the beginning of gastrulation (4.5-6.5 d.p.c.) occur within the first two days of embryoid body differentiation. Between days 3 and 5, embryoid bodies contain cell lineages found in embryos during gastrulation at 6.5 to 7.0 d.p.c., and after day 6 in culture, embryoid bodies are equivalent to early organogenesis-stage embryos (7.5 d.p.c.). In addition, we demonstrate that the panel of developmental markers can be applied in a screen for stage- or lineage-specific genes. Reporter gene expression from entrapment vector insertions can be co-localized with expression of specific markers within the same cell during embryoid body formation as well as during embryogenesis. Our results thus demonstrate the power of embryoid body formation as an in vitro model system to study early lineage determination and organogenesis in mammals, and indicate that they will prove to be useful tools for identifying developmental genes whose expression is restricted to particular lineages.

Animals↗

PubMed1998

Regional analysis of the spatial patterns of Fos induction in brain following flurothyl kindling.

We have recently demonstrated that eight, daily flurothyl-induced generalized clonic seizures, followed by a four week stimulus-free interval, results in a long-lasting reduction in generalized seizure threshold and a change in the type of seizure expressed in response to flurothyl from clonic to tonic. There is a progressive increase in the probability that a mouse will express a tonic seizure during the four week interval, suggesting that prior flurothyl seizures initiate a proepileptogenic process that requires time to develop. In this study, the immunohistochemical detection of the c-fos protein (Fos) was used to evaluate whether seizure-induced epileptogenesis resulted in regional differences in the degree of neuronal activation. Fos immunoreactivity was examined 1.5 h following either a single generalized seizure, the last of eight consecutive daily seizures or a retest seizure evoked two weeks after the last of eight seizures. In each condition, generalized seizure behaviours were elicited in C57BL/6 mice using flurothyl and classified as either "forebrain" (face and forelimb clonus) or "brainstem" (running/bouncing, treading, tonic extension). The spatial distribution of Fos induction was compared on the basis of the seizure phenotype and the seizure history. The predominant differences in Fos distribution were found to be related to the type of seizure expressed regardless of the seizure history. Furthermore, the different motor components that make up a "brainstem" seizure could not be distinguished by the pattern of Fos labelling suggesting that multiple convulsive behaviours are mediated by one anatomical system. Finally, Fos induction in the ventromedial hypothalamic nucleus preceded and predicted the change in seizure type from "forebrain" to "brainstem". These data support the concept that separate anatomical systems mediate the expression of the two generalized seizure phenotypes. In addition, the ventromedial nucleus of the hypothalamus may be a point of interaction between the systems and may play a role in seizure-induced neural reorganization.

Animals↗

PubMed1995

[Temporal and spatial pattern analysis of pharyngeal swallowing in patients with abnormal sensation in the throat].

There are many patients who complain of abnormal sensations, such as an obstructive sensation, foreign body sensation, difficulty in swallowing, etc., in the throat, which do not have an obvious cause. The causes of such unpleasant symptoms have not been adequately investigated. As one of the potential factors in volved in abnormal sensations in the throat, we considered the existence of subclinical dysphagia. We then performed videofluoroscopic analysis in patients with an abnormal sensation in the throat to examine whether or not there were functional disorders in swallowing. Videofluoroscopy was performed in 42 subjects, 30 patients with abnormal sensation in the throat and 12 volunteers without swallowing problems. We devised a temporal and spatial analysis system of swallowing using personal computer technology. Videofluoroscopic swallowing sequences during spoon feeding (3-5ml) and drinking from a cup (15-20ml) of liquid barium, were analyzed. The results suggest that two temporal measurements of swallow from videofluoroscopic studies are appropriate for parameter of subclinical dysphagia: the time it takes the bolus to move through pharynx from the point at which the bolus head passes the tongue base until the bolus head extends caudally beyond the piriform sinus while feeding from a spoon (S2), and the time it takes the bolus to move through the upper esophagus from the point at which the bolus head passes the bottom of the piriform sinus until the bolus tail passes the same point while drinking from a cup (C1). Then, we selected C1 and S2 for variables and detect the patients who have subclinical dysphagia with cluster analysis. Forty-two subjects were divided into two groups: those composed of 14 patients (cluster 1), and those composed of 16 patients and 12 controls (cluster 2). We thought 14 patients in cluster 1 would have subclinical dysphagia for the cause of abnormal sensation in the throat. Temporal and spatial analysis revealed three forms of pharyngeal swallow in cluster 1. In 6 patients, the bolus stall in the valleculae prior to the onset of the pharyngeal swallow. In other 6 patients, the bolus stall in the piriform sinus before swallowing reflex. In the other 2 patients, the bolus moved smoothly but slowly without delay in pharynx. Our results indicate that a delayed swallowing reflex is the main functional finding in videofluoroscopy in patients with subclinical dysphagia contributing to an abnormal sensatin in the throat.

Adult↗

PubMed2004

[Regional spatial patterns of water circumstances in loess plateau area based GIS].

Based on the integration of GIS and geo-synthesis analysis, the water circumstances for plant growth in the Shaanxi Loess Plateau area were studied and a map reflecting regional water circumstances at the scale of 1:500,000 was made. The results showed that the water circumstances for plant growth in the Loess Plateau area were affected by the integration of precipitation soil texture, loess deposition, geomorphology and coverage, and could be measured by sub-indicators from the mentioned aspects. The index from the view point of plant development was used for the water circumstance assessment. The water circumstances of the Loess Plateau including forest zone, shrub zone and grassland zone appeared a complex spatial mosaic structure, and the main of the plateau was suitable for forestry which meant the plateau had an expected potential for eco-restoration.

China↗

PubMed1996

Temporal-spatial pattern of c-fos expression in the rat brain in response to indispensable amino acid deficiency. I. The initial recognition phase.

Rats reduce their food intake after ingestion of a small amount of an amino acid imbalanced (AA-IMB) diet that induces a pronounced amino acid deficiency. Two hours after ingesting a threonine-IMB diet, just when food intake is depressed significantly, the concentration of threonine is decreased in some but not all brain areas. Neural recognition of this decrease in the limiting amino acid is thought to be the first step in the anorectic responses to AA-IMB diets. To identify the regions of the brain that may be activated upon recognition of an AA-IMB diet, we examined the temporal-spatial distribution of Fos immunoreactive neurons at intervals after introduction of either threonine-IMB or control diets. We found that Fos immunoreactivity in the anterior piriform cortex and immediately surrounding areas, along with the infralimbic cortex, was increased selectively early (by 2 h) after introduction of the AA-IMB diet, and remained elevated through 3 h. The anterior piriform cortex is believed to function in neural recognition of amino acid deficiency. Fos immunoreactivity in the AA-IMB group increased over the control diet groups somewhat later in the dorsomedial nucleus of the hypothalamus. We hypothesize that these areas in the rostral forebrain may serve as neural relays in the early phases of the anorectic responses that occur upon recognition of amino acid deficiency.

Amino Acids↗

PubMed1990

Hydroxyproline-Rich Glycoprotein Transcripts Exhibit Different Spatial Patterns of Accumulation in Compatible and Incompatible Interactions between Phaseolus vulgaris and Colletotrichum lindemuthianum.

The distribution of transcripts encoding hydroxyproline-rich glycoproteins in hypocotyls of Phaseolus vulgaris L. infected with Colletotrichum lindemuthianum was examined by in situ hybridization to tissue sections. The expression of hypersensitive resistance in an incompatible interaction was accompanied by a massive early accumulation of transcripts in the epidermal, cortical, and perivascular parenchymal tissues immediately adjacent to the inoculation site. In a compatible interaction, there was no accumulation of transcripts in the epidermal and cortical tissues even though fungal hyphae ramified throughout these tissues. However, transcripts accumulated at a later stage in the perivascular tissue directly below the site of infection and in tissue several millimeters from the inoculation site. Thus, there is a spatial and tissue-specific counterpart to the differential timing of transcript accumulation in incompatible versus compatible interactions (AM Showalter, JN Bell, CL Cramer, JA Bailey, CJ Lamb [1985] Proc Natl Acad Sci USA 82: 6551-6555). These differences in the spatial distribution and tissue specificity of transcript accumulation imply the differential induction of signaling systems involved in race:cultivar-specific interactions.

Journal Article↗

PubMed2004

Monitoring change in spatial patterns of disease: comparing univariate and multivariate cumulative sum approaches.

Prospective disease surveillance has gained increasing attention, particularly in light of recent concern for quick detection of bioterrorist events. Monitoring of health events has the potential for the detection of such events, but the benefits of surveillance extend much more broadly to the quick detection of change in public health. In this paper, univariate and multivariate cumulative sum methods for disease surveillance are compared. Although the univariate method has been previously used in the context of health surveillance, the multivariate method has not. The univariate approach consists of simultaneously and independently monitoring the disease rate in each region; the multivariate approach accounts explicitly for any covariation between regions. The univariate approaches are limited by their lack of ability to account for the spatial autocorrelation of regional data; the multivariate methods are limited by the difficulty in accurately specifying the multiregional covariance structure. The methods are illustrated using both simulated data and county-level data on breast cancer in the northeastern United States. When the degree of spatial autocorrelation is low, the univariate method is generally better at detecting changes in rates that occur in a small number of regions; the multivariate is better when change occurs in a large number of regions.

Breast Neoplasms↗

PubMed1982

Analysis of temporal and spatial patterns of rat vestibular hair cell differentiation by tritiated thymidine radioautography.

The location in time and space of the terminal mitoses of type I and type II sensory hair cells (HCI and HCII) of the developing crista ampullaris in rat lateral semicircular canal and macula utriculi was determined by radioautographs of specimens exposed to tritiated thymidine from the 13th to the 20th day of gestation. Qualitative analysis and statistical treatment of the percentages of labeled HCI and HCII show that the terminal mitoses occur first in the macula utriculi with a maximum percentage of the 14th day of gestation, for the HCI, and on the 15th day of gestation, for the HCII. In the lateral crista, the maximum percentage of labeled HCI occurs on the 17th and 18th day of gestation and on the 19th day of gestation for the HCII. A spatial distribution of this labeling activity is also described: the older cells are located at the top of the crista and at the level of the striola of the macula utriculi while the younger cells are found at the bottom of the crista and on the sides of the utricle. A study of the vestibular receptors in the fetuses shows that synaptic contacts already exist on the 18th day of gestation in the macula utriculi at the level of the striola and on the 19th day at the top of the crista; the cells situated on the periphery are still immature. The first hair cells to undergo their terminal mitoses are, therefore, connected first. These results also suggest that the two types of cells are genetically programmed and that the HCI start functioning first during the development of the labyrinth.

Acoustic Maculae↗