摘要:

AbstractWe recently demonstrated that large numbers of neurons in the spinal cord of rats project directly to the hypothalamus. In the present study, we used the retrograde tracer Fluoro‐Gold (FG) to examine this projection more completely. In the first series ofss studies, we attempted to label the entire population of spinal cord neurons that project to the hypothalamus. Injections that virtually filled the hypothalamus on one side without spreading into any other diencephalic area labeled a large number of neurons (estimated to be more than 9,000 in the case with the most neurons labeled) bilaterally at all levels of the spinal cord. Approximately 60° of the labeled neurons were contralateral to the injection. The greatest number of labeled neurons was found within the deep dorsal horn. Many were also found within the lateral spinal nucleus, the superficial dorsal horn, and the gray matter surrounding the central canal. A small number of labeled cells was located in the intermediate zone and ventral horn of the spinal gray matter. Labeled neurons were distributed bilaterally within the sacral parasympathetic nucleus and trigeminal nucleus caudalis.Injections of FG restricted to the medial hypothalamus labeled neurons within the spinal cord in a distribution similar to that produced by injections that filled the hypothalamus. However, fewer neurons were labeled in the spinal cord (estimated to be more than 6,200) and trigeminal nucleus caudalis.Injections of FG restricted to the lateral hypothalamus also labeled fewer neurons (approximately 3,300) than did injections that filled the hypothalamus. In these cases, also, the pattern of labeled neurons within the spinal cord was similar to that produced by injections within either medial or both medial and lateral hypothalamus. However, few neurons were labeled in the sacral parasympathetic nucleus following injections into the lateral hypothalamus.These findings show the distribution of a large number of spinal cord neurons that project directly to medial or lateral hypothalamic regions that are involved in autonomic, neuroendocrine, and emotional responses to somatosensory stimulation, including painful stimu

ISSN:0092-7317    

DOI:10.1002/cne.902910302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe terminal colon of thels/lsmouse is aganglionic because an intrinsic defect prevents its colonization by cells migrating from the neural crest. Previous studies showed that laminin, type IV collagen, and glycosaminoglycans accumulate in the region of the presumptive aganglionicls/lsbowel through which crest‐derived cells would be expected to migrate. It was suggested that crest‐derived cells might fail to enter the abnormal bowel because they receive inappropriate signals from a defective extracellular matrix. This hypothesis was evaluated by analyzing the ultrastructure of the extracellular matrix in mutant and control gut. Tissue was fixed in the presence of ruthenium red before or after selective enzymatic digestion. Heparan sulfate proteoglycan (diameter ≅ 15 nm) and chondroitin sulfate proteoglycan (diameter ≅ 20‐50 nm) granules were found in both control and presumptive aganglionic gut. The heparan sulfate proteoglycan granules were primarily located within formed basal laminae, while chondroitin sulfate proteoglycan granules decorated plasma membranes and 5 nm hyaluronic acid microfibrils that formed a network in the extracellular matrix. At day E11.5, the mutant gut differed from the control in the following: (1) Hyaluronic acid microfibrils were longer and more numerous. (2) There were larger numbers of chondroitin sulfate proteoglycan granules associated with cell membranes and with hyaluronic acid microfibrils. By day E13 the spaces between mesenchymal cells of the outer wall of the control bowel contained a regular lattice of hyaluronic acid microfibrils studded with chondroitin sulfate proteoglycan granules. Instead of this lattice, tangles of excessively long hyaluronic acid microfibrils, coated more heavily than in the control with chondroitin sulfate proteoglycan granules, were found in the presumptive aganglionic gut. These results confirm that the extracellular matrix is abnormal in the presumptive aganglionic bowel of thels/lsmouse; moreover, they also indicate that the defect involves not one, but several components of the extracellular matrix, as well as their distribution. The defective extracellular matrix is apparent at a time when crest‐derived cells would be expected to be migrating in the terminal bowel and is located in their path. The observations thus support the idea that a localized abnormality of the extracellular matrix interferes with the colonization of the terminal bowel by crest‐derived cells in

ISSN:0092-7317    

DOI:10.1002/cne.902910303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractGrowth hormone releasing factor (GRF) neurons in the arcuate nucleus of the hypothalamus and somatostatin (SRIF) neurons in the anterior periventricular region of the hypothalamus act to control the release of growth hormone from the anterior pituitary. To investigate the possibility that the growth‐controlling functions of these cells might be compromised by injuries to the developing brain, it is important to know the details of the production and differentiation of these small, specialized cell groups. The overall pattern of cell production in the hypothalamus is known from autoradiographic studies with general nuclear stains, but no data are available on the birthdates (times of final mitoses) of GRF‐producing cells. The present study was undertaken to determine when the GRF cells form. Counts of immunocytochemically identified GRF cells labeled on given days were taken from serial coronal sections through the hypothalamus of adult rats labeled on the 10th‐17th days of gestation (day of finding a vaginal plug = day 1). As has been shown for the hypothalamus in general, the GRF cells showed a gradient of production from anterior to posterior. The peak of anterior cell proliferation was on day 13, middle cells on day 14, and posterior cells on day 15. These dates are 1 or 2 days earlier than those of GRF‐negative cells in the same regions. No lateral to medial gradient of formation was seen in GRF cells. Rather, the laterally placed cells along the base of the brain and those surrounding the ventromedial nucleus formed simultaneously with the GRF cells of the arcuate nucleus. The birthdating results presented here are in agreement with the results of studies of teratogens which suggest that rat postnatal growth is reduced most severely by exposure to neurotoxic agents on days 12 or 13 of gestation. On the basis of data for the whole hypothalamus, such treatments would appear to be too early to interfere with cell production for the arcuate nucleus, but the timing fits the period of vulnerability as defined by the birthdates determined in the present study for the subpopulation of cells destined to prod

ISSN:0092-7317    

DOI:10.1002/cne.902910304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe segmental and topographical organization of motoneurons innervating the infrahyoid (IH) and the spinal accessory (AC) Muscles was studied in the Japanese monkey (Macaca fuscata) with thje retrograde horseradish peroxidase (HRP) method after application of HRP to the peripheral nerve branches supplying the IH and AC inuscles. IH motoneurons constitute two distinct slender cell columns, a longer medial and a shorter lateral one. The medial cell column extends from the most caudal level of the hypoglossal nucleus to the lower levels of the sececond cervical (C2) cord segment. In the medial column, motoneurons supplying the sternohyoid and sternothyroid muscles are distributed at the medullary and C1 levels, while those innervating the omohyoid muscle are primarily distributed at the C2 level. The lateral cell column consists of motoneurons supplying the thyrohyoid muscle and extends from the most caudal level of the hypoglossal nucleus to the middle levels of the C1 cord segment. Axons of thyrohyoid motoneurons follow a dorsomedially directed bent emergent course, making a hairpin turn.AC motoneurons supplying the sternocleidomastoid (SC) and trapezius (TZ) muscles form a single slender cell column extending from the most rostral level of the pyramidal decussation to the middle levels of the C6 cord segment. SC motoneurons are distributed from the most rostral level of the pyramidal decussation to the middle levels of the C3 cord segment, while TZ motoneurons are distributed from the upper levels of the C2 cord segment to the lower levels of the C6 cord segment. At the levels of the C2 and C3 cord segments, both SC and TZ motoneurons are distributed in the AC cell column; the cluster of SC motoneurons is located dorsomedial to that of TZ motoneurons.

ISSN:0092-7317    

DOI:10.1002/cne.902910305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractWe used an antiserum directed against γ‐aminobutyric acid (GABA) fixed with glutaraldehyde (Hoskins et al., Cell Tissue Res. 244:243‐252, '86) to label neurons with GABA‐like immunoreactivity (GLI) in wholemounts of the stomatogastric ganglion and each segmental ganglion of crayfish, except the brain. Each abdominal ganglion had an average of 63 labeled neurons, or 10% of all their neurons. Each peripheral nerve of each abdominal ganglion except the last contained labeled axons. Within each segment, the first peripheral nerve, N1, had five axons; the second peripheral nerve, N2, had at most four; and the third peripheral nerve, N3, had two. In the last ganglion, N2 had one labeled axon, N3 had two and N6 had two; the other nerves contained no labeled axons. A tabulation of the identified inhibitory neurons in the abdominal ganglia revealed that 40% of these GABA‐ergic neurons have been identified. The subesophageal ganglion had many labeled neurons in clusters that formed a repeating pattern; it also had labeled neurons near its dorsal midline. The thoracic ganglia contained more labeled neurons than did the abdominals, but their patterns of labeling were similar. The commissural ganglia contained three clusters of labeled neurons and sent labeled axons to the esophageal ganglion. The esophageal ganglion contained four labeled neurons and many labeled axons. The stomatogastric ganglion contained labeled axon terminals but no labeled

ISSN:0092-7317    

DOI:10.1002/cne.902910306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractInfant macaques recover tactile abilities better than older animals after somatosensory cortical lesions. To investigate the neural basis of this phenomenon, we ablated the hand representation in primary somatosensory cortex (SI) of infant and juvenileMacaca mulattaand recorded in ipsilateral second somatosensory cortex (SII) a year later. We also made tracer injections to verify the lesion boundaries and to study the connections of SII after the lesion of SI. Similar to the report of Pons et al. (Science 237:417‐420, '87), we found that substantial portions of the SII hand area were unresponsive to cutaneous stimulation of the hand in both age groups. Particularly, there were no cutaneous receptive fields restricted to the digits. Some responses were elicited in each animal by mechanical stimulation of the hand, including a proportion related to cutaneous receptive fields. This proportion was higher in the infants than in the juveniles, which may explain the greater capacity of the infants for recovery of tactile function after SI lesions. The residual somatic drive in the SII hand area of the juveniles was attributable to sparing of parts of areas 3a and 3b. However, in the infants, this explanation was not tenable since the responses noted in SII occurred even after total ablations of the postcentral gyrus. The pattern of corticocortical connections revealed by injections of HRP into the medial margin of the SI lesion and of Fast Blue into SII in one infant confirmed the absence of SI inputs to the region of SII where responses were recorded from the hand. Representations of body parts other than the hand were normally responsive, and their location was consistent with normal somatotopy in SI

ISSN:0092-7317    

DOI:10.1002/cne.902910307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractOlivocerebellar fiber maturation was examined in normal and lurcher mutant mice between postnatal day 5 (P5) and P15, using the anterograde transport of wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP) from the inferior olive. Immunocytochemistry for the Purkinje cell marker PEP‐19 was used to demonstrate Purkinje cell development in the same material. In mutant and normal animals, a regional developmental variation is observed such that, when compared at a given age, cortex lining the vermal fissures appears developmentally advanced over cortex in the cerebellar hemispheres. In the primary fissure of the normal animals, the first recognizable Purkinje cell dendrites appear on P6, and the olivocerebellar fibers first enter the climbing stage of their development on P9. In lurcher animals Purkinje cell development proceeds on this schedule, but olivocerebellar fibers are never observed to enter the molecular layer. These afferents maintain dense perisomatic nests around Purkinje cells, even in P13‐15 lurchers. Examination of P14 lurchers by transmission electron microscopy indicates that the olivocerebellar fibers form synapses on Purkinje cell somatic spines and that the basket cell axons fail to form their typical perisomal nests around Purkinje cells. In addition, parallel fibers can be observed to synapse on dendritic spines on the Purkinje cell primary dendrites. We interpret these results as indicating a recognition defect between olivocerebellar fibers and Purkinje cell dendrites. An analysis of this defect in lurcher may reveal how the normal transformation of olivocerebellar fibers, from perisomal to dendritic terminals, is a

ISSN:0092-7317    

DOI:10.1002/cne.902910308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe mammalian cerebellar cortex consists of a number of parasagittal Purkinje cell compartments that can be demonstrated cytochemically. The afferent inputs to the cerebellum are also compartmentalized, and a complex but reproducible relationship exists between the afferents and the intrinsic maps. Developmental studies in the rat have shown that many of the main features of compartmentation are already established at birth, and are therefore not easily manipulated experimentally. The compartmentation antigen zebrin II is expressed selectively by Purkinje cell subsets in a range of species, including fish and primates. In this study, zebrin II immunoreactivity has been studied in the grey opossum,Monodelphis domestica, in order to develop a marsupial model of compartment formation in which the early developmental events are more readily accessible. A monoclonal antibody to zebrin II from the weakly electric fishApteronotusrecognizes a 36 kD polypeptide in homogenates ofMonodelphiscerebellum that appears to be identical to the antigen in the rat.Immunocytochemistry reveals that zebrin II in adultMonodelphisis confined exclusively to the cerebellum, where it is expressed by a subset of Purkinje cells. All regions of the cell, except the nucleus, are stained. The zebrin II+Purkinje cells are arranged in a set of parasagittal compartments interposed by similar zebrin II−compartments. In each hemicerebellum there is one zebrin II+band abutting the midline (P1+), and two others laterally in the vermis (P2+, P3+). A fourth zebrin II+compartment straddles the paravermian region (P4+). Three other compartments have been identified in the hemisphere (P5+, P6+, P7+). This arrangement is very similar to that found in the rat. During postnatal development, zebrin II is first expressed between P14 and P21 in Purkinje cells of the posterior lobe vermis, and spreads throughout the cerebellar cortex by P28. As in rat, there is a stage at which all Purkinje cells are zebrin II+, including those destined to be zebrin II−in the adult. The mature pattern of expression emerges after P35 as immunoreactivity gradually disappears from the cells destined to become zebrin II−. The adult appearance is attained only after P56. The developmental timetable is therefore similar to that in rat, but is rather more protracted.Monodelphisshould prove to be a valuable experimental model in which to study the early events leading to the formation of cerebellar compart

ISSN:0092-7317    

DOI:10.1002/cne.902910309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe production of song in passerine birds is under the control of steroid hormones, and brain regions involved in song production have been shown to contain androgen and/or estrogen receptors. Studies to date, however, have not considered the possible role of progestins in this behavior. As one approach to this question, the autoradiographic method was used to investigate the distribution of progestin‐concentrating cells in the brain of the adult male zebra finch (Poephila guttata) after injection of the radiolabeled synthetic progestin [17α‐methyl‐3H]‐promegestone. In the telencephalon, identifiable groups of progestin‐accumulating cells were found in the hyperstriatum dorsale, at the medial edge of the lobus parolfactorius, and in the medial septum. In the diencephalon, labeled groups of cells were found in the preoptic area, through much of the medial hypothalamus‐‐including nucleus periventricularis magnocellularis, nucleus medialis hypothalami posterialis, and area infundibularis‐‐and in the medial spiriform nucleus and dorsomedial thalamus. In the myelencephalon, labeled cells are described at the dorsal edge of the medulla and scattered lateral to nXII. These findings offer no support for the hypothesis that progestin acts on any of the known song regions, but do suggest areas of progestin action in the avian central nervous system outside of the known song system. Not surprisingly, these include many areas of the medial hypothalamus and other

ISSN:0092-7317    

DOI:10.1002/cne.902910310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe expression of the highly polysialylated form of the neural cell adhesion molecule (N‐CAM)—the so‐called embryonic N‐CAM (E‐N‐CAM)‐was investigated in the developing and adult mouse cerebellar cortex by immunohistology and immunocytology at the light and electron microscopic levels. E‐N‐CAM was never (from embryonic day 14 to postnatal day 15) detectable in the germinal zone of neuroblasts destined to form or forming the external granular layer and was only observed once small cerebellar interneurons had become postmitotic before the beginning of granule cell migration. Granule cells expressed E‐N‐CAM on cell bodies, axons, and leading and trailing processes also during migration but ceased to reveal detectable levels of E‐N‐CAM at the end of migration after having reached their final position in the internal granular layer. Other cerebellar cell types, such as Purkinje cells, Bergmann glia, astrocytes, oligodendrocytes, and most prominently, stellate and basket cells, also expressed E‐N‐CAM, but became E‐N‐CAM‐negative during the third and fourth postnatal weeks, coinciding with overt cessation of cerebellar histogenesis. Thus, except for neuroblasts, E‐N‐CAM appeared characteristic of growing and moving cellular structures, in agreement with the notion that the highly polysialylated form of N

ISSN:0092-7317    

DOI:10.1002/cne.902910311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY