Mediolateral damping of an overhead body weight support system assists stability during treadmill walking.

BACKGROUND: Body weight support systems with three or more degrees of freedom (3-DoF) are permissive and safe environments that provide unloading and allow unrestricted movement in any direction. This enables training of walking and balance control at an early stage in rehabilitation. Transparent systems generate a support force vector that is near vertical at all positions in the workspace to only minimally interfere with natural movement patterns. Patients with impaired balance, however, may benefit from additional mediolateral support that can be adjusted according to their capacity. An elegant solution for providing balance support might be by rendering viscous damping along the mediolateral axis via the software controller. Before use with patients, we evaluated if control-rendered mediolateral damping evokes the desired stability enhancement in able-bodied individuals. METHODS: A transparent, cable-driven robotic body weight support system (FLOAT) was used to provide transparent body weight support with and without mediolateral damping to 21 able-bodied volunteers while walking at preferred gait velocity on a treadmill. Stability metrics reflecting resistance to small and large perturbations were derived from walking kinematics and compared between conditions and to free walking. RESULTS: Compared to free walking, the application of body weight support per-se resulted in gait alterations typically associated with body weight support, namely increased step length and swing phase. Frontal plane dynamic stability, measured by kinematic variability and nonlinear dynamics of the center of mass, was increased under body weight support, indicating reduced balance requirements in both damped and undamped support conditions. Adding damping to the body weight support resulted in a greater increase of frontal plane stability. CONCLUSION: Adding mediolateral damping to 3-DoF body weight support systems is an effective method of increasing frontal plane stability during walking in able-bodied participants. Building on these results, adjustable mediolateral damping could enable therapists to select combinations of unloading and stability specifically for each patient and to adapt this in a task specific manner. This could extend the impact of transparent 3-DoF body weight support systems, enabling training of gait and active balance from an early time point onwards in the rehabilitation process for a wide range of mobility activities of daily life.

The efficacy of hyaluronic acid in postextraction sockets of impacted third molars: A pilot study.

OBJECTIVE: This study aims to evaluate the effectiveness of local hyaluronic acid (HA) administration to surgically remove impacted third molar sockets and measure pain, swelling, and trismus. MATERIALS AND METHODS: The study included a total of 25 healthy patients aged 18-29 years with asymptomatic bilaterally impacted lower third molars. All cases have been performed under local anesthesia. In the study group, 0.8% HA (Gengigel®) was applied in the postextraction sockets of the right third molars and in the control group nothing was applied to the extraction sockets of the left third molars. Postoperative pain, trismus, and swelling were evaluated on the 1st, 3rd, and 7th postoperative days. RESULTS: No difference was determined between groups in facial swelling and maximum mouth opening. However, the amount of pain significantly reduced in HA groups according to visual analog scale (P = 0.001). CONCLUSION: The results of this study showed that HA can produce an analgesic action in postextraction sockets after surgical removal of impacted teeth and therefore it has a clinical benefit to reduce usage of nonsteroidal anti-inflammatory drugs after dentoalveolar surgery.

Changes to insulin sensitivity in glucose clearance systems and redox following dietary supplementation with a novel cysteine-rich protein: A pilot randomized controlled trial in humans with type-2 diabetes.

We recently developed a novel keratin-derived protein (KDP) rich in cysteine, glycine, and arginine, with the potential to alter tissue redox status and insulin sensitivity. The KDP was tested in 35 human adults with type-2 diabetes mellitus (T2DM) in a 14-wk randomised controlled pilot trial comprising three 2×20 g supplemental protein/day arms: KDP-whey (KDPWHE), whey (WHEY), non-protein isocaloric control (CON), with standardised exercise. Outcomes were measured morning fasted and following insulin-stimulation (80 mU/m2/min hyperinsulinaemic-isoglycaemic clamp). With KDPWHE supplementation there was good and very-good evidence for moderate-sized increases in insulin-stimulated glucose clearance rate (GCR; 26%; 90% confidence limits, CL 2%, 49%) and skeletal-muscle microvascular blood flow (46%; 16%, 83%), respectively, and good evidence for increased insulin-stimulated sarcoplasmic GLUT4 translocation (18%; 0%, 39%) vs CON. In contrast, WHEY did not effect GCR (-2%; -25%, 21%) and attenuated HbA1c lowering (14%; 5%, 24%) vs CON. KDPWHE effects on basal glutathione in erythrocytes and skeletal muscle were unclear, but in muscle there was very-good evidence for large increases in oxidised peroxiredoxin isoform 2 (oxiPRX2) (19%; 2.2%, 35%) and good evidence for lower GPx1 concentrations (-40%; -4.3%, -63%) vs CON; insulin stimulation, however, attenuated the basal oxiPRX2 response (4%; -16%, 24%), and increased GPx1 (39%; -5%, 101%) and SOD1 (26%; -3%, 60%) protein expression. Effects of KDPWHE on oxiPRX3 and NRF2 content, phosphorylation of capillary eNOS and insulin-signalling proteins upstream of GLUT4 translocation AktSer437 and AS160Thr642 were inconclusive, but there was good evidence for increased IRSSer312 (41%; 3%, 95%), insulin-stimulated NFκB-DNA binding (46%; 3.4%, 105%), and basal PAK-1Thr423/2Thr402 phosphorylation (143%; 66%, 257%) vs WHEY. Our findings provide good evidence to suggest that dietary supplementation with a novel edible keratin protein in humans with T2DM may increase glucose clearance and modify skeletal-muscle tissue redox and insulin sensitivity within systems involving peroxiredoxins, antioxidant expression, and glucose uptake.

Human ß-defensins differently affect proliferation, differentiation, and mineralization of osteoblast-like MG63 cells.

Purpose of this study was to investigate whether human ß-defensins (hBDs) affect maturation and proliferation of osteoblast-like MG63 cells in vitro. Osteoblast-like MG63 cells were stimulated with hBD-1, -2, and -3 under control conditions and with hBD-2 during experimental inflammation (induced by interleukin-1ß, tumor necrosis factor-α, toll-like receptor-2 and -4 agonists). Expression of different osteogenic markers and hBDs were analyzed by real-time PCR, immunohistochemistry, and enzyme-linked immunosorbent assay. In addition, alkaline phosphatase (ALP) enzyme activity and biomineralization as markers for differentiation were monitored. All tested hBDs were expressed on mRNA and protein level in MG63 cells. Only stimulation with hBD-2 elevated the proliferation rate. hBD-2 and hBD-3 positively affected the differentiation of osteoblast-like cells provided by increased transcript levels of osteogenic markers, up-regulated ALP enzyme activity and enhanced mineralized nodule formation. All pro-inflammatory stimuli enhanced interleukin-6 and hBD-2 expression and down-regulated markers of osteoblastic differentiation. In accordance, inflammation increased transcript level of Notch-1 (an inhibitor of osteoblastic differentiation). hBD-2 was not able to revert effects of inflammation on differentiation. In bone cells human ß-defensins exhibit further functions than antimicrobial peptide activity. These include stimulation of proliferation and differentiation. Differentiation arrest due to inflammation could not be overcome by hBD-2 alone.

Complete denture displacement following open-mouth reline.

In 21 complete denture wearers, six upper and 15 lower denture relines were performed with the open-mouth technique. The centric relation (CR) was recorded with the Central-Bearing-Point (CBP) method three times before and three times after the reline. For each registration, the right and left condylar position was recorded in three dimensions using a custom-made measuring device. The average denture displacement from an initial reference position (CR) was calculated for each registration. An upper denture reline leads to a mean displacement of 2·5 mm, both in the right and left condylar area. With an average of 2·0 mm, this displacement was smaller following a lower denture reline (right and left mean, 1·6 mm). The precision of the CBP-registrations proved 0·5 mm before and 0·3 mm after reline; hence, the measured condylar displacement after reline could not attribute to a methodological bias. This clinical-experimental study demonstrates that relining complete dentures with the open-mouth technique may lead to a substantial denture shift and thus imply inevitably clinically relevant occlusal discrepancies. It is therefore important to carefully check the occlusion at denture delivery and remount the prostheses if necessary.

[Adapted and standardised patient management in the treatment of neovascular AMD in the outpatient setting of a university eye hospital]. / Angepasstes und standardisiertes Patientenmanagement bei der Behandlung der neovaskulären AMD im ambulanten Bereich einer Universitäts-Augenklinik.

Visual results in treating neovascular age-related macular degeneration (AMD) using intravitreal injected anti-VEGF (IVT) clearly depend on injection frequency. Regarding to the European approval Ranibizumab has to be used only in cases of recurrent visual loss after the loading phase. In contrast monthly treatment--as also provided in the ANCHOR and MARINA studies--is generally allowed in Switzerland. However, it is commonly tried to reduce the injection frequency because of the particular cost situation in all health systems and of cause also due to the necessary strict monitoring and reinjection regimes, which raise management problems with increasing patient numbers. In this article the special treatment regimes of our University Eye Hospital is presented, in which a reduced injection frequency basically leads to the same increased and stable visual results as in ANCHOR and MARINA; however, needing significantly more injections as generally provided in other countries of Europe. The main focus for achieving this in a large number of patients is placed on re-structuring our outpatient flow for IVT patients with particular emphasis on patient separation and standardisation of treatment steps leading to significantly reduced time consumption per patient. Measurements of timing and patient satisfaction before and after restructuring underline its importance in order to be able to treat more patients at a high quality even in the future. The exceptional importance of spectral domain OCT measurements as the most important criterium for indicating re-treatment is illustrated.

Neurons in the rat dentate gyrus granular layer substantially increase during juvenile and adult life.

Volumetric estimates of the total number of granule cells in rats 30, 120, 200, and 365 days old increase linearly by approximately 35 to 43 percent between 1 month and 1 year. Total volume of the granular layer also grows linearly during that time. These results demonstrate a numerical increase in a neuronal population during adulthood in the mammalian brain.

In situ hybridization analysis of Girk2 expression in the developing central nervous system in normal and weaver mice.

A mutation in the gene Girk2 that encodes an inwardly rectifying potassium channel is the genetic defect causing the behavioral and pathologic abnormalities of the weaver mutant mouse. Of the pathologic abnormalities, the best studied is the neuronal degeneration that occurs in the cerebellar cortex and in the midbrain dopaminergic neurons. A detailed characterization of the topographic and temporal expression of Girk2 is fundamental to elucidate the mechanisms underlying neurodegeneration in these mutant mice. In this study we utilized in situ hybridization to determine the expression of Girk2 mRNA during prenatal and postnatal development in the murine central nervous system (CNS). Girk2 expression was seen in multiple regions of embryonic CNS including the cerebellum and midbrain. During postnatal development, the highest expression was seen in the cerebellum, midbrain and hippocampus. However, since the developing cerebellum undergoes significant neuronal loss due to the degeneration of granule cell precursors, Girk2 mRNA expression in this area decreases progressively.

The development of the septal region in the rat. II. Morphogenesis in normal and x-irradiated embryos.

Morphogenesis of the septal region was examined in normal rat embryos from embryonic day (E) 10 to E22. The greater part of the septal region is postulated to form from two separate anlagen which can be clearly distinguished in the telencephalon by E13 and E14. One lies in the anterior ventromedial wall and presumably forms the nucleus of the diagonal band, medial, lateral, and triangular septal nuclei. The other lies in the posterior ventrolateral ridge and presumably forms the bed nuclei of the stria terminalis and the anterior commissure. On E15, the early differentiating cells in these anlagen fuse in the same region where the anterior commissure will cross on E17. With later embryonic development, differentiating cells of the strial bed nucleus accumulate rostral and caudal to the fused area. The same pattern is found in the medial and triangular septal nuclei and in the nucleus of the diagonal band. The differentiating cells of the lateral septal nucleus accumulate dorsal and lateral to medial and triangular septal nuclei. On E16 and E17, a prominent subependymal zone develops in the anterior septal region and presumably gives rise to the nucleus accumbens. A quantitative analysis was made of three cell zones (neuroepithelium, subependymal zone, differentiating cell zone) at coronal levels through the developing nucleus accumbens and the nucleus of the diagonal band (anterior level) and the medial and lateral septal nuclei (middle and posterior levels). At all levels, the area of the neuroepithelium continually declines, that of the differentiating cell zone continually increases, and that of the subependymal zone shows a rise and decline. On a proportional basis, both the neuroepithelium and subependymal zone occupy significantly more area anteriorly than posteriorly, while the differentiating cell zone shows the reverse gradient. To accurately locate regions of primitive mitotic and migratory cells within the zones at each level, the number of cells surviving a single exposure to 200 R X-rays in embryonic brains (E15-E22) were compared with controls. Each zone responded differently to X-ray insult. The radiosensitivity of the neuroepithelium decreases significantly after E19; the subependymal zone is highly radiosensitive throughout; the differentiating cell zone is radioresistant throughout. The significance of these findings is discussed in the light of the autoradiographic determination of the time of formation of septal neurons (Bayer, '79).

The development of the septal region in the rat. I. Neurogenesis examined with 3H-thymidine autoradiography.

Neurogenesis in the rat septal region was examined with 3H-thymidine autoradiography. The rats in the prenatal groups were the offspring of pregnant females given two injections of 3H-thymidine on consecutive days in an overlapping series: embryonic day (E) 13 + E14, E14 + E15,. . . E21 + E22. The rats in the postnatal groups were injected in a nonoverlapping series: the day of birth and postnatal day (P) 1, P2 + P3, P3 + P4. On 60 days of age, the percentage of labelled cells and the proportion of cells added during each day of formation were determined at several anatomical levels within the midline nuclear group (nucleus of the diagonal band, medial and triangular septal nuclei), the lateral septal nucleus, and the ventrolateral nuclear group (nucleus accumbens, bed nuclei of the stria terminalis and the anterior commissure). The neurons within each nuclear group form in significantly different waves, those of the midline group forming between E13-E17, the lateral septal nucleus between E15-E19, the bed nuclei of the stria terminalis and anterior commissure between E14-E18, the nucleus accumbens between E17-P2. All nuclei and nuclear groups show characteristic gradients of formation. Both the midline nuclear group and the bed nucleus of the stria terminalis (including the commissural bed nucleus) have their earliest forming neurons lying near the crossing of the anterior commissure; younger nuerons are located both rostrally and caudally with the youngest neurons lying in the most rostral extension of the diagonal band nucleus and the strial bed nucleus. The lateral septal nucleus forms along a strong mediolateral gradient throughout its length after neurogenesis is almost complete in the midline nuclear group. Throughout the length of the nucleus accumbens, the oldest neurons are located ventrally while progressively younger cells are found dorsally beneath the inferior horn of the lateral ventricle.

Neurogenetic and morphogenetic heterogeneity in the bed nucleus of the stria terminalis.

Neurogenesis and morphogenesis in the rat bed nucleus of the stria terminalis (strial bed nucleus) were examined with [3H]thymidine autoradiography. For neurogenesis, the experimental animals were the offspring of pregnant females given an injection of [3H]thymidine on 2 consecutive gestational days. Nine groups of embryos were exposed to [3H]thymidine on E13-E14, E14-E15,... E21-E22, respectively. On P60, the percentage of labeled cells and the proportion of cells originating during 24-hour periods were quantified at six anteroposterior levels in the strial bed nucleus. On the basis of neurogenetic gradients, the strial bed nucleus was divided into anterior and posterior parts. The anterior strial bed nucleus shows a caudal (older) to rostral (younger) neurogenetic gradient. Cells in the vicinity of the anterior commissural decussation are generated mainly between E13 and E16, cells just posterior to the nucleus accumbens mainly between E15 and E17. Within each rostrocaudal level, neurons originate in combined dorsal to ventral and medial to lateral neurogenetic gradients so that the oldest cells are located ventromedially and the youngest cells dorsolaterally. The most caudal level has some small neurons adjacent to the internal capsule that originate between E17 and E20. In the posterior strial bed nucleus, neurons extend ventromedially into the posterior preoptic area. Cells are generated simultaneously along the rostrocaudal plane in a modified lateral (older) to medial (younger) neurogenetic gradient. Ventrolateral neurons originate mainly between E13 and E16, dorsolateral neurons mainly between E15 and E16, and medial neurons mainly between E15 and E17. The youngest neurons are clumped into a medial "core" area just ventral to the fornix. For morphogenesis, pregnant females were given a single injection of [3H]thymidine during gestation, and their embryos were removed either 2 hours later (short survival) or in successive 24-hour periods (sequential survival). The embryonic brains were examined to locate areas of intensely labeled cells in the putative neuroepithelium of the strial bed nucleus, to trace migratory waves of young neurons, and to establish their final settling locations. Two different neuroepithelial sources produce neurons for the strial bed nucleus. The anterior strial bed nucleus is generated by a neuroepithelial zone at the base of the inferior horn of the lateral ventricle from the anterior commissural decussation area forward to the primordium of the nucleus accumbens.(ABSTRACT TRUNCATED AT 400 WORDS)

Development of the brain stem in the rat. III. Thymidine-radiographic study of the time of origin of neurons of the vestibular and auditory nuclei of the upper medulla.

Groups of pregnant rats were injected with two successive daily doses of 3H-thymidine from gestational days 12 and 13 (E12 + 13) until the day before parturition (E21 + 22). In adult progeny of the injected rats the proportion of neurons generated on specific embryonic days was determined quantitatively in the vestibular and auditory nuclei of the upper medulla. In the vestibular nuclei, neurons are generated between days E11 and E15 in an overlapping sequential order, yielding a lateral-to-medial and a rostral-to-caudal internuclear gradient. In the lateral vestibular nucleus peak production time is day E12; in the superior nucleus, E13; in the inferior nucleus, E13 and E14; and in the medial nucleus, E14. The early generation of neurons of the lateral vestibular nucleus may reflect the early differentiation of the circuit from the gravity receptors (utricle) to neurons of the spinal cord controlling postural balance. The later production of neurons of the superior vestibular nucleus may reflect the subsequent differentiation of the circuit from the rotational receptors (semicircular canals) to the neurons of the brain stem controlling eye movements. The generation time of neurons of the nucleus prepositus hypoglossi overlaps with that of the medial vestibular nucleus. The neurons of the anteroventral and posteroventral cochlear nuclei are produced from days E13 to E17, with no temporal differences between the two nuclei. The neurons of the dorsal cochlear nucleus are generated over a very long time span, beginning on day E12 and extending into the postnatal period. There is a sequence in the production of neurons forming the different layers of the dorsal cochlear nucleus in the following order: pyramidal cells, cells of the inner layer, cells of the outer layer and, finally, cells of the granular layer. There is also a sequential production of neurons in four nuclei of the superior olivary complex. In the lateral trapezoid nucleus peak production time is day E12; in the medial superior olivary nucleus, day E13; in the medial trapezoid nucleus, day E15; and in the lateral superior olivary nucleus, day E16. This order yields a medial-to-lateral gradient in the dorsal aspect of the superior olivary complex, and a lateral-to-medial gradient ventrally. These mirror-image gradients were also seen intranuclearly in the lateral superior olivary nucleus and the medial trapezoid nucleus. The cytogenetic gradients could not be related to tonotopic representation; however, they could be related to the lateral location of ipsilateral cochlear nucleus input to the lateral superior olivary nucleus and the medial location of the contralateral cochlear nucleus input to the medial trapezoid nucleus.

Development of the brain stem in the rat. IV. Thymidine-radiographic study of the time of origin of neurons in the pontine region.

Groups of pregnant rats were injected with two successive daily doses of 3H-thymidine from gestational day 12 and 13 (E12 + 13) until the day before parturition (E21 + 22) in order to label in their embryos the proliferating precursors of neurons. At 60 days of age the proportion of neurons generated (or no longer labeled) on specific embryonic days was determined quantitatively in 14 nuclei of the pontine region. Peak production time of neurons of the trigeminal mesencephalic nucleus was on day E11 or earlier, with a small proportion generated on day E12. Peak production time of the trigeminal motor neurons was on day E12, with a small proportion produced earlier. Neurons of the principal sensory nucleus were generated between days E13 and E16, with a peak on day E14; the late-produced neurons tended to belong to a class of intermediate and large cells. The bulk of the neurons of the supratrigeminal and infratrigeminal nuclei arose on days E15 and E16. Neurons of the locus coeruleus are produced mostly on day E12, with about 20% of the cells arising on day E13. The bulk of the neurons of the dorsal tegmental nucleus (Gudden's) are produced between days E13 and E15, whereas most of the neurons of the deep (ventral) tegmental nucleus are produced on day E15. A dorsal-to-caudal gradient was also obtained between the dorsal and ventral nuclei of the lateral lemniscus, the neurons of the former being generated between days E12 and E15; the latter, between days E13 and E17. The neurons of both the pars lateralis and the pars medialis of the parabrachial nucleus were produced simultaneously between days E13 and E15, with a peak on day E13. The heterogeneous collection of neurons of the pontine paramedial reticular formation was produced for day E11 (or earlier) until day E15. Finally, the neurons of the raphe pontis parvicellularis were generated at an even rate between days E13 and E15, whereas the bulk of the neurons of the raphe pontis magnocellularis were produced on days E15 and E16. On the basis of datings obtained for 9 subdivisions of the entire brain stem trigeminal complex, hypotheses were offered of the cytogenetic components of the system. The sequence of neuron production in the dorsal and deep tegmental nuclei was related to their connections with divisions of the mammillary and habenular nuclei on a "first come-first serve" basis.

Development of the precerebellar nuclei in the rat: I. The precerebellar neuroepithelium of the rhombencephalon.

Short-survival thymidine radiograms from rat embryos aged 13-19 days were analyzed to delineate the precerebellar neuroepithelium of the rhombencephalon. The original definition of the term "rhombencephalon" was modified to refer only to the unique dorsal portion (surface plate) of the medulla and pons where the neural groove fails to fuse and, instead, the medullary velum covers the rhomboid lumen of the fourth ventricle. Initially, the neuroepithelial tissue of the rhombencephalon consists of a pair of rostral and caudal bridgeheads: the former the primary neuroepithelium of the cerebellum and the latter the primary neuroepithelium of the octavo-precerebellar system. The spatial relationship between the cerebellar and precerebellar neuroepithelia soon changes as a result of ongoing morphogenetic events, such that the cerebellar primordium assumes a dorsal position and the precerebellar primordium a ventral position, and the distance between the two decreases. Concurrently the tela choroidea invaginates into the fourth ventricle and a secondary precerebellar neuroepithelium develops. The rostral portion of the secondary precerebellar neuroepithelium grows forward along the choroid plexus and forms the medial recess of the anterior fourth ventricle, while its caudal portion grows in the opposite direction beneath the medullary velum and forms the rostral wall of the posterior fourth ventricle. Evidence will be presented in the succeeding papers that the primary precerebellar neuroepithelium first generates the neurons of the inferior olive that migrate by a circumferential intramural (parenchymal) route to their destination. Next, the neurons of the lateral reticular and external cuneate nuclei are generated. These migrate by a posterior extramural (superficial) route and settle contralaterally. Subsequently, the primary precerebellar neuroepithelium produces the neurons of the nucleus reticularis tegmenti pontis and these form the anterior extramural migratory stream and settle ipsilaterally. Finally, the secondary precerebellar neuroepithelium produces the latest generated neurons of the basal pontine gray that follow the anterior extramural stream and settle ipsilaterally.

Development of the precerebellar nuclei in the rat: II. The intramural olivary migratory stream and the neurogenetic organization of the inferior olive.

Sequential thymidine radiograms from rats labeled on days E13 and E14, and killed at daily intervals thereafter, were analyzed to trace the migratory route and settling pattern of neurons of the inferior olive. Long-survival thymidine radiograms from perinatal rats injected on day E14 were used to subdivide the inferior olivary complex on the basis of neurogentic criteria. The inferior olivary neurons originate on days E13 and E14 in the primary precerebellar neuroepithelium. The olivary neurons labeled on day E14 (the late generated components) translocate into the inferior olivary premigratory zone on day E15. On day E16 these cells join the olivary migratory stream, which follows an intramural circumferential path between the gray and white matters of the medulla. By day E17 the olivary migratory stream is reduced to a small band near the corpus of the inferior olive, which has been settled by this time by neurons generated on day E13. As a result, the unlabeled cells are situated on day E17 dorsomedially and the labeled cells ventrolaterally. The regional segregation of neurons forming subdivisions of the inferior olive begins on day E18, and by day E19 the major subdivisions are all recognizable. In thymidine radiograms from perinatal rats injected on day E14, four neurogenetic components can be distinguished in the inferior olive, those composed: (1) of unlabeled cells (generated on day E13), (2) of predominantly unlabeled cells, (3) of predominantly labeled cells (generated on day E14), and (4) of labeled cells. By combining these neurogenetic differences with the morphological features of the inferior olivary complex, we propose a modification of the currently accepted classification. The four major divisions of the inferior olive are the successively produced posterodorsal olive, anterolateral (principal) olive, posteroventral olive, and anteroventral olive. The location and configuration of these divisions are illustrated in relation to the traditional classification both in the coronal and the sagittal plane.

Development of the precerebellar nuclei in the rat: III. The posterior precerebellar extramural migratory stream and the lateral reticular and external cuneate nuclei.

Sequential thymidine radiograms from rats injected on day E15 and killed thereafter at daily intervals up to day E22 were analyzed to trace the migratory routes and settling patterns of neurons of the lateral reticular nucleus and the external cuneate nucleus. The neurons of the lateral reticular and external cuneate nuclei originate in the primary precerebellar neuroepithelium at the same site as the inferior olivary neurons but follow a different migratory route. The labeled young neurons that are produced on day E15 (the last one-third of the total) join the posterior precerebellar extramural migratory stream. The cells move circumferentially over the wall of the medulla in a ventral direction and by day E17 reach the midline and cross it beneath the inferior olive. The crossing cells apparently continue to migrate circumferentially on the opposite side. One complement of these cells begins to form a ventrolateral extramural condensation on day E19. By day E20 some cells begin to penetrate the parenchyma and settle as neurons of the lateral reticular nucleus. The settling of the lateral reticular neurons continues on the following day, and by day E22 all the cells destined for the lateral reticular nucleus have penetrated the parenchyma. A dorsomedial-to-ventrolateral neurogenetic gradient is indicated for the settling lateral reticular neurons. Another complement of migrating cells continues dorsally and forms a condensation on day E19 that we interpret as the external cuneate component of the crossed stream. These cells begin to penetrate the parenchyma on day E20, and by days E21 and E22 two components of the external cuneate nucleus are identifiable-the dorsal and ventral external cuneate nuclei. The neurons of the lateral reticular and external cuneate nuclei differ from neurons of all the other precerebellar nuclei in that their cerebellar projection is predominantly ipsilateral. We speculate that the axons of all precerebellar neurons are genetically specified to cross the midline ventrally to provide a contralateral efferent projection, but this is modified in the case of the ipsilaterally projecting lateral reticular and external cuneate neurons by the cell bodies following their neurites to the opposite side.

Development of the precerebellar nuclei in the rat: IV. The anterior precerebellar extramural migratory stream and the nucleus reticularis tegmenti pontis and the basal pontine gray.

Sequential thymidine radiograms from rats injected on days E16, E17, E18, and E19 and killed 2 hours after injection and at daily intervals up to day E22 were used to establish the site of origin, migratory route, and settling patterns of neurons of the nucleus reticularis tegmenti pontis and basal pontine gray. The nucleus reticularis tegmenti pontis neurons, which are produced predominantly on days E15 and E16, derive from the primary precerebellar neuroepithelium. These cells, unlike those of the lateral reticular and external cuneate nuclei, take an anteroventral subpial route, forming the anterior precerebellar extramural migratory stream. This migratory stream reaches the anterior pole of the pons by day E18. In rats injected on day E16 and killed on day E18 some of the cells that reach the pons are unlabeled, indicating that they represent the early component of neurons generated on day E15. The cells labeled on day E16 begin to settle in the pons on day E19, 3 days after their production. These cells, migrating in an orderly temporal sequence, form a posterodorsal-to-anteroventral gradient in the nucleus reticularis tegmenti pontis. Unlike the neurons of all the other precerebellar nuclei, the basal pontine gray neurons derive from the secondary precerebellar neuroepithelium. The secondary precerebellar neuroepithelium forms on day E16 as an outgrowth of the primary precerebellar neuroepithelium, and it remains mitotically active through day E19, spanning the entire period of basal pontine gray neurogenesis. The secondary precerebellar neuroepithelium is surrounded by a horizontal layer of postmitotic cells, representing the head-waters of the anterior precerebellar extramural migratory stream. In rats injected on day E18 and killed on day E19 the cells are labeled in the proximal half of the stream around the medulla but those closer to the pons are unlabeled, indicating an orderly sequence of migration. In rats injected on day E18 and killed on day E20 the labeled cells reach the pole of the pons. In the basal pontine gray the sequentially generated neurons settle in a precise order. The neurons generated on day E16 form a small core posteriorly and the neurons generated on days E17, E18, and E19 form regular concentric rings around the core in an inside-out sequence.

Development of the preoptic area: time and site of origin, migratory routes, and settling patterns of its neurons.

Neurogenesis and morphogenesis in the rat preoptic area were examined with [3H]thymidine autoradiography. For neurogenesis, the experimental animals were the offspring of pregnant females given an injection of [3H]thymidine on two consecutive gestational days. Nine groups were exposed to [3H]thymidine on embryonic days E13-E14, E14-E15, E21-E22, respectively. On postnatal day P5, the percentage of labeled cells and the proportion of cells originating during 24-hr periods were quantified at four anteroposterior levels in the preoptic area. Throughout most of the preoptic area there is a lateral to medial neurogenetic gradient. Neurons originate between E12-E15 in the lateral preoptic area, between E13-E16 in the medial preoptic area, between E14-E17 in the medial preoptic nucleus, and between E15-E18 in the periventricular nucleus. These structures also have intrinsic dorsal to ventral neurogenetic gradients. There are two atypical structures: (1) the sexually dimorphic nucleus originates exceptionally late (E15-E19) and is located more lateral to the ventricle than older neurons; (2) in the median preoptic nucleus, where older neurons (E13-E14) are located closer to the third ventricle than younger neurons (E14-E17). For an autoradiographic study of morphogenesis, pregnant females were given a single injection of [3H]thymidine during gestation, and their embryos were removed either two hrs later (short survival) or in successive 24-hr periods (sequential survival). Short-survival autoradiography was used to locate the putative neuroepithelial sources of preoptic nuclei, and sequential survival autoradiography was used to trace the migratory waves of young neurons and their final settling locations. The preoptic neuroepithelium is located anterior to and in the front wall of the optic recess. The neuroepithelium lining the third ventricle is postulated to contain a mosaic of spatiotemporally defined neuroepithelial zones, each containing precursor cells for a specific structure. The neuroepithelial zones and the migratory waves originating from them are illustrated. Throughout most of the preoptic area, neurons migrate predominantly laterally. The older neurons in the lateral preoptic area migrate earlier and settle adjacent to the telencephalon. Younger neurons migrate in successively later waves and accumulate medially. The sexually dimorphic neurons are exceptional since they migrate past older cells to settle in the core of the medial preoptic nucleus.(ABSTRACT TRUNCATED AT 400 WORDS)

Development of the rat thalamus: I. Mosaic organization of the thalamic neuroepithelium.

Short-survival, sequential, and long-survival thymidine radiograms of rat embryos, fetuses and young pups were analyzed in order to delineate the boundaries of the proliferative thalamic neuroepithelium, describe its early transformations, identify its regional divisions, and, finally, attempt to relate its distinct neuroepithelial components to specific thalamic nuclei that they supply with neurons. On day E13 the thalamic neuroepithelium consists of two divisions, the rostral lobe and the caudal lobe, and interposed between the two is a small transient structure, the reticular protuberance. By day E14 the rostral lobe has become partitioned into the anterior lobule and the reticular lobule, and the caudal lobe into the intermediate lobule and the posterior lobule. By day E15 these four lobules have become further partitioned into sublobules, characterized as regional eversions and inversions (concavities and convexities) of the thalamic neuroepithelium. Several of these sublobules are still recognizable on day E16 but progressively disappear thereafter. In this introductory paper, some evidence is presented in support of the hypothesis that the identified thalamic sublobules represent putative cell lines committed to produce neurons for specific, early-generated thalamic nuclei. Detailed documentation of the evidence on which the identifications are based is provided in subsequent papers of this series which deal with the early development of specific thalamic regions and nuclei. In our attempt to identify these putative cell lines, we sought to meet the following criteria: (1) a good match between the time course of mitotic activity in a neuroepithelial sublobule and the birth days of neurons in the nucleus that it is postulated to supply with neurons, (2) relative proximity between the putative neuroepithelial source and the thalamic target structure, and, where possible, (3) the tracing of migrating cells from the germinal source to its destination. Using these criteria we have made the following tentative identifications. The early derivatives of the anterior thalamic lobules are the sublobules (committed cell lines) of the anterior thalamic nuclei, and of the central lateral and mediodorsal nuclei. The early derivatives of the reticular lobule and reticular protuberance are the sublobules of the reticular nuclear complex. The early derivatives of the intermediate lobule are the sublobules of the ventrolateral and ventrobasal nuclei. Finally, the early derivatives of the posterior lobule are the sublobules of the dorsal geniculate, ventral geniculate, and medial geniculate nuclei.(ABSTRACT TRUNCATED AT 400 WORDS)

Development of the rat thalamus: III. Time and site of origin and settling pattern of neurons of the reticular nucleus.

Short-survival, sequential, and long-survival thymidine radiograms of rat embryos, fetuses, and young pups were analyzed in order to examine the time of origin, settling pattern, migratory route, and site of origin of neurons of the reticular nuclear complex of the thalamus. On the basis of its chrono-architectonics, the reticular nucleus was divided into a central, medial, and lateral subnucleus. The central subnucleus is the earliest produced component of the entire thalamus with over 50% of its neurons being generated on day E13 and another 40% on day E14. Peak production of neurons of the lateral and medial subnuclei is on day E14. There is a lateral (earlier) to medial (later) neurogenetic gradient between these two components of the reticular complex: only about 12% of the lateral subnucleus neurons, but close to 30% of the medial subnucleus neurons, are generated on day E15. Because the lateral and medial subnuclei display the typical outside-in gradient found in the thalamus, they are considered to constitute a single cytogenetic sector; the early generated central subnucleus, which violates this order, is considered to constitute a separate cytogenetic sector. Observations are presented that neurons of the central reticular subnucleus originate in a unique neuroepithelial region, the reticular protuberance. The migration of heavily labeled cells was traced from this region in rats labeled with 3H-thymidine on day E13 and killed on the subsequent days. The neurons of the lateral and medial reticular subnuclei originate in the reticular lobule of the thalamic neuroepithelium. The migration of heavily labeled, spindle-shaped cells was traced from this region in rats labeled with 3H-thymidine on days E14 and E15 and killed at daily intervals thereafter. The neurogenetic gradient of the reticular thalamic complex seen in postnatal rats is established before birth.