摘要:

AbstractA soluble form of the D2 glycoprotein, detected in the rat brain hypotonic extract, is described. Its specific relative concentration did not differ significantly in the three examined cerebral regions (forebrain, brainstem and cerebellum), while in the cerebellum the membrane‐bound form was about three and four times more concentrated than in the forebrain and brainstem, respectively. No sizeable developmental variations of the soluble D2 concentration could be detected in forebrain, whereas the amount of the membrane‐bound protein rose from birth to postnatal day 6 and then decreased to the adult value (about 40% of the newborn concentration). Ontogenetic modifications of the membranous D2 glycans (studied through the binding of the molecule to several lectins) occur around postnatal day 18 when the binding to Ricinus communis lectin, specific for galactose, becomes evident. At all ages both soluble and membrane‐bound forms bind to Concanavalin A, specific for mannose and glucose, and to wheat germ agglutinin, specific forN‐acetylglucosamine, while the lack of binding to Ulex europeus lectin suggests the absence of discrete amount of fucose. The results are discussed in relation to the possible involvement of D2 glycoprotein in cell‐to‐cell adhesion.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90001-7

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe ontogenesis of immunoreactive (ir) LHRH neurons was investigated in rats applying the double‐bridge PAP method of Vaccaet al. (J. Histochem. Cytochem.28, 297–307, 1980). Ir LHRH was first evident in the cell bodies confined in the ventromedial surface of the anterior part of the forebrain vesicles on day 16.5 of gestation. Only one or two cells, if any, were found in the brains examined; the cells are oval showing ir brown granules within the perikarya and also within the processes extended from both poles. On day 17.5 of gestation, a few ir cells appeared in the olfactory cortex, medial septum, medial preoptic area, diagonal band of Broca, and ventro‐lateral surface of the anterior hypothalamus, and, with development, their numbers increased gradually. During the prenatal period, no ir cell exists in the arcuate nucleus or in the medial‐basal hypothalamus. Beaded ir fibers appeared in the organum vasculosum of the lamina terminalis (OVLT) and in the external layer of the median eminence on 18.5 and 19.5 days of gestation, respectively. The present findings ascertain that the hypothalamic regulation of hypophysial gonadotrophic function exists during fetal period in rats.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90002-9

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractA degeneration of the retinal cone photoreceptor cells, but not of the rod photoreceptor cells, is present in rhesus monkeys raised from birth for 26 months on a commercially available human infant protein hydrolyzate formula. This degeneration is associated with a selective decrease in plasma taurine concentration, and is entirely prevented by supplementing the formula with taurine. A reduced conedominated ERG was present at 10 months, but not at 18 or 26 months. These results suggest that the implications of the reduced taurine concentrations in human infants fed synthetic formulas containing little or no taurine should be reconsidered, since adverse effects on the visual system may only be detectable at the ultrastructural level.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90003-0

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe effect of brain extracts from rat and beef, and of 2′,5′‐dibutyryl cyclic AMP on the CAII content was investigated in rat primary glial cultures maintained in serum‐containing or serum‐free medium. All cultures contained a mixed population of oligodendroglial and astroglial cells, but under certain conditions the cultures were highly enriched in oligodendroglial cells. An immunocytochemical positive reaction to CAII was observed in oligodendrocytes, while astrocytes were not stained. The content of CAII per culture and per oligodendroglial cell was higher after treatment of the culture with soluble brain extract and a partially purified fraction. A combined autoradiographic‐ immunohistochemical study, after [3H]thymidine incorporation and staining for CAII, showed that under the influence of rat brain extract the number of mitotic CAII positive cells was greater at day 11 compared to control cultures. But the proliferation rate decreased with time in culture after brain extract treatment and the number of mitotic CAII positive cells became far below that of controls. Since at the same time CAII quantity per cell was higher in the treated ones it is suggested that brain extract not only influences the proliferation of oligodendroglial cells, but also their maturation. The addition of 2′,5′‐dibutyryl cyclic AMP had no effect on oligodendroglial cells and the amount of CAII in the cultures was not affected. It is discussed that agents, which stimulate 3′,5′‐cyclic AMP content, may not influence the CAII content, but may stimulate the enzymatic activity.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90004-2

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThein vivouptake by neuroepithelial cells of rat serum proteins injected into the mesencephalic cavity of developing chicken was demonstrated by immunohistochemical methods. It was found that 48 h after inoculation, rat alphafetoprotein (AFP) and serum albumin (SA) localize in the same places as do chicken AFP and SA. No labelling was present for rat or chicken IgG. We also present evidence showing that chicken ovalbumin, which is not normally found inside ependymal cells is not internalized even when injected into the cerebrospinal fluid at 30‐fold its physiological concentration. The existence of transient specific receptors which could be responsible for this protein uptake is proposed. The possible implications in relation to developmental biology are discussed.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90005-4

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractWe sought to examine further the regulation of muscarinic receptors in the developing expansor secundariorum, a smooth muscle of the avian wing. [3H]Quinuclidinyl benzilate binding was used as a measure of muscarinic receptors present in the muscle, which gradually decline in density from hatch during the following few weeks. Receptor loss can be prevented by denervation of the muscle immediately after hatch, but receptor density is not recovered by denervation in older birds. As the major innervation is provided by sympathetic, noradrenergic fibres with no evidence of a cholinergic input, the action of several pharmacological agents known to affect noradrenergic transmission was examined. Reserpine partially prevented the early receptor decline but phenoxybenzamine and dimethylphenylpiperazinium did not significantly affect receptor density. The muscle was also immobilized by tenotomy, since this unique muscle is attached to the shoulder by a long, discrete tendon. Tenotomy significantly retarded the normal developmental receptor loss. It is suggested that in this muscle, muscarinic receptor density is regulated by noradrenergic nerves, possibly by a mechanism involving the transmitter, noradrenaline.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90006-6

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractHypothyroidism induced by perinatal administration of propylthiouracil (PTU) had profound effects on growth of the heart, with major organ weight deficits persisting well beyond the termination of drug treatment. These effects were preceded by disruption of the developmental patterns of cardiac ornithine decarboxylase (ODC) and the polyamines, which are thought to be intracellular modulators of cellular maturation. Activity of cardiac ODC was depressed in the PTU‐treated group and putrescine and spermidine levels were markedly subnormal. PTU administration also affected brain growth, but much less so than in the heart. The disruption of the brain ODC/polyamine system was also less pronounced, with relatively small degrees of spermidine depletion and a slight elevation of ODC. For both tissues, the biochemical effects of perinatal hypothyroidism were opposite to those found previously for administration of exogenous thyroid hormones. These results support the views that: (1) endogenous thyroid hormones contribute to the maintenance of normal developmental patterns of ODC and the polyamines, and (2) the ODC/polyamine system participates in events modulating subsequent tissue growth.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90007-8

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractNeurogenesis in the rat neostriatum was examined with [3H]thymidine autoradiography. For the animals in the prenatal groups, the initial [3H]thymidine exposures were separated by 24 h; they were the offspring of pregnant females given two injections on consecutive embryonic (E) days (E13–E14, E14–E15, … E21–E22). For the animals in the postnatal (P) groups, the initial [3H]thymidine exposures were separated by 48 h, each group receiving four consecutive injections (P0–P3, P2–P5, P4–P7). On P60, the percentage of labeled cells and the proportion of cells originating during either 24 or 48 h periods were quantified at several anatomical levels for both the large and medium‐sized neurons. Neurogenesis of the large neurons occurs mainly between E13 and E16 in a strong caudal‐to‐rostral gradient. The medium‐sized neurons throughout the neostriatum are generated in a prominent ventrolateral‐to‐dorsomedial gradient so that ventrolateral cells originate mainly between E14 and E18, dorsomedial cells between E18 and E21–22 (fewer than 10% originate between P0 and P4). Medium‐sized neurons also show two other gradients. First, there is a superficial‐to‐deep gradient in the anterior part of the caudoputamen, while more posterior levels have a deep‐to‐superficial gradient. Second, anterior parts have a caudal‐to‐rostral gradient while posterior parts have a gradient in the opposite direction. This shift in neurogenetic gradients along both superficial‐deep and rostrocaudal directions is developmental evidence that an anterior ‘caudate’ can be separated from a posterior ‘putamen’ in the rat. Finally, neurogenetic gradients in the medium‐sized caudoputamen neurons can be linked to the patterns of their anatomical interconnections with the substantia nigra.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90008-X

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractCiliary neuronotrophic factors (CNTFs) are proteins defined by their ability to promote the survival in tissue culture of chick embryo ciliary ganglionic neurons. CNTF activity has been reported in several source materials. Among these sources, the highest specific activity, i.e. 16,000 TU/mg, has been found in the intraocular tissue innervated by the ciliary ganglionic neurons. We now report that extracts of adult rat peripheral nerve and spinal nerve roots contain CNTF at a specific activity equal to or greater than the intraocular tissue. Equally high concentrations of CNTF activity are found in both motor and sensory nerves. The possible cellular source(s) of this mammalian CNTF is discussed.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90009-1

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe presence and morphology of GFA‐ and vimentin‐positive astrocytes were studied immunohistochemically in rats using smear preparations of single intraocular grafts of the cortex cerebri anlage and of cortex pieces grafted to eyes containing a previously grafted piece of the locus coeruleus area. Similarly, astrocytes were studied in lesioned cortex cerebriin situ. A high number of GFA and vimentin‐positive cells were found in smears of both types of cortex grafts as well as in smears of the lesioned cortex cerebriin situ. In contrast, only a limited number of GFA‐positive astrocytes were seen in smears of normal cortex. Using computerized image analysis, the two‐dimensional cell area and cell perimeter were found to be significantly increased in individual GFA‐positive astrocytes in both types of intraocular cortex grafts as well as in the lesioned cortex when compared to GFA‐positive astrocytes in normal cortex cerebri.GFA‐positive cells in smears of cortex grafts from locus coeruleus‐cortex combinations had significantly smaller cell area and cell perimeter values compared to similar cells from single cortex grafts. A similar, although less pronounced difference was observed between vimentin‐positive cells from the same type of grafts. This suggests that the presence of the mature locus coeruleus graft in some as yet unknown way influences the development of the adjacent cortex graft towards a more normal astrocytic maturation. An additional finding was the large size difference between GFA‐ and vimentin‐positive cells in the intraocular grafts. Since most evidence indicates that vimentin‐positive cells are also GFA‐positive, this may indicate that the two intermediate filament systems have a partially different distribution within individual astrocytes.It is concluded that computerized image analysis of smears processed for immunohistochemistry with antisera against GFA and vimentin is a useful technique for studies of astrocyte morphology in normal as well as experimentally perturbed CNS tissue. Cortex tissue that develops in contact with a locus coeruleus graft in the eye chamber show a significantly lesser degree of gliosis than cortex tissue developing in isolation in the eye.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90010-8

出版商:Wiley    

年代:2003

数据来源: WILEY