摘要:

AbstractThis study correlates the ontogeny of basic fibroblast growth factor (FGF) with the development of the vasculature of the anterior pituitary (AP) in two strains of rat, Sprague‐Dawley (SD) and Fischer 344 (F344). Immunolocalization of FGF was followed from the first appearance of Rathke's pouch (RP) in 12‐day (12d) fetuses, through each day of fetal development, and in 5, 20, and 50d postnatal female rats. In addition, the ontogeny of folliculo‐stellate cells (FSC) is described, since previous studies suggested that these unique cells might function as phagocytes in the regulation of FGF. In both rat strains, vascularization of the AP commenced in 16d fetuses. In 15–20d fetuses, dense foci of immunopositivity for extracellular FGF were apparent at sites of capillary penetration adjacent to partially disrupted, immature gonadotropes. Localization of FGF was first detected in immature gonadotropes in 18d fetuses and persisted in the cytosol of a subpopulation of gonadotropes thereafter. In 15d fetuses, FGF was localized within the cytosol intimately associated with the peripheral‐facing plasma membranes of all cells of the adenohypophysis, and persisted to variable degrees in later fetal stages. Localization of FGF within nuclei of AP parenchymal cells was evident only in 16–17d fetuses. Although the ontogeny of FGF and vascularization of the AP was very similar in both rat strains, the ontogeny of FSC differed markedly. In both strains, follicular lumens contained FGF during late fetal and early postnatal development. However, both electron microscopy and immunostaining for S‐100 marker protein revealed that the postero‐lateral edges of the AP of F344 rats often lacked FSC when compared to SD rats, a situation which could compromise regulation of FGF by FSC at the AP periphery in that strain, and thereby contribute to the neovascularization from systemic blood vessels known to occur in that strain during prolactinoma formation. © 1993

ISSN:1058-8388    

DOI:10.1002/aja.1001970202

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

年代:1993

数据来源: WILEY

摘要:

AbstractCD9 is a cell surface protein implicated in intercellular signaling that has been identified in selected cell types of the hematopoietic system. To begin a study of the role of CD9 in the developing and adult nervous system, we used the anti‐rat CD9 monoclonal antibody ROCA2 to determine the distribution of this protein. The identity of the antigen in these tissues was confirmed by immunoblotting and peptide sequencing. Early embryonic sympathetic and dorsal root ganglion sensory neurons and adrenal chromaffin cells all express CD9. ROCA2 also labels the somas, axons, and growth cones of cultured sympathetic and sensory neurons. In the central nervous system (CNS), CD9 is transiently and specifically expressed in embryonic spinal motorneurons. In the adult, central and peripheral glia intensely express CD9. Thus, CD9 is developmentlly regulated in a variety of peripheral and central neurons and glia, including proliferating progenitors as well as mature cells. These findings suggest that CD9 may have diverse roles in the nervous system. © 1993 Wiley‐Liss,

ISSN:1058-8388    

DOI:10.1002/aja.1001970203

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

年代:1993

数据来源: WILEY

摘要:

AbstractF9 embryonal cells can be induced to differentiate and synthesize basement membrane proteins. Perlecan and laminin are two basement membrane constituents that have extensive regions of homology. Expression of perlecan and laminin B1 genes was followed during differentiation of F9 cells by measurements of transcription rate and mRNA abundance using nuclear run on assays and Northern hybridizations, respectively. The rate of precursor protein synthesis was determined by immunoprecipitation from lysates of pulse‐labeled F9 cells. The results showed that perlecan gene expression responds more rapidly after induction than does laminin B1 gene expression but is ultimately expressed at a substantially lower level than laminin. Thus, the perlecan and laminin genes appear to be regulated by different mechanisms and their gene products are not made in stoichiometric amounts. © 1993 Wiley‐Liss,

ISSN:1058-8388    

DOI:10.1002/aja.1001970204

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

年代:1993

数据来源: WILEY

摘要:

AbstractSynaptic vesicles are essential for neuronal synaptic function. We have analyzed the temporal and spatial pattern of mRNA accumulation of two integral membrane proteins specific for synaptic vesicles (synaptophysin and SV2) and a small GTP‐binding protein associated with the vesicles (rab3a), using in situ hybridization to mouse embryonic tissue sections. Our results indicate that transcription of these mRNAs is not synchronous in the embryo. Detectable levels of synaptophysin and rab3a mRNAs appear during early neurulation (embryonic day [ED] 9.5) both in the CNS and PNS, whereas SV2 mRNA is not observed before ED 10.5. We have also compared the accumulation of these synaptic vesicle protein transcripts during neuroblast proliferation and neuronal differentiation in vitro, using as a model system the embryonic carcinoma cell line P19 which can be induced to differentiate into neurons and glial cells. We observe that transcripts for all three proteins appear in neurons virtually simultaneously soon after withdrawal from the cell cycle. These data suggest that the program of differentiation in vitro is similar to that observed in vivo, but markedly accelerated. In both embryos and P19 cells, transcripts for these three proteins are detectable at a time when most of the neurons have withdrawn from the cell cycle, but prior to neurite extension and synapse formation. © 1993 Wiley‐Liss,

ISSN:1058-8388    

DOI:10.1002/aja.1001970205

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

年代:1993

数据来源: WILEY

摘要:

AbstractMany projection systems within the peripheral and central nervous system are topographically organized, and it has become increasinging clear that interactions which occur during development determine the projection patterns these systems exhibit in the adult. The olivocerebellar system was chosen as a model system for this study of afferent pattern formation because it has several characteristics which lend themselves to a study of this type. Applications of horseradish peroxidase were made to both the cerebellar primordium and to the inferior olive of embryonic and neonatal mice using an in vitro perfusion system to support the tissue during the transport period. Fibers labeled after restricted olivary applications are limited to particular mediolateral regions of the cerebellum. Similarly, olivary cells retrogradely labeled after discrete cerebellar applications are restricted to particular olivary subdivisions. The results indicate that the olivocerebellar projection displays elements of topographic organization as early as E15 and that the pattern displayed is roughly comparable to that of the adult mammal. The observed trajectories of olivocerebellar fibers and their concomitant association with both Purkinje and cerebellar nuclear cells during embryonic development suggests a role for either or both cell types in the pattern formation process. © 1993 Wiley‐Liss, I

ISSN:1058-8388    

DOI:10.1002/aja.1001970206

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe spatial and temporal distribution of transcripts for the TRE/CRE‐binding basic region‐leucine zipper protein hXBP‐1 was determined by in situ hybridization. Analysis of embryos from day 10.5 to 18.5 pc revealed high level expression of hXBP‐1 RNA in two developing organ systems: (1) in bone and cartilage cells of the developing skeleton and toothbuds, and (2) in exocrine glands including the pancreas and the submandibular and salivary glands. High level expression was also found in whisker follicles and in selected cells in brown adipose tissue. In the developing skeleton, hXBP‐1 RNA was expressed starting on day 11.5 pc in osteoblasts of newly formed intramembranous bone. Thereafter, hXBP‐1 was expressed in both osteoblasts and preosteoblasts in bone formed directly by intramembranous formation as well as in bone formed during endochondral ossification. The most intese signal was observed in preosteoblasts and osteoblasts of newly forming bone. At day 11.5 pc low level hXBP‐1 expression was also observed in matrix secreting chondroblasts of bones which are formed initially of cartilage, at the stage where they consist entirely of cartilage, at the stage where they consist entirely of cartilage. Signal was also present in matrix producing chondroblasts of the mature zone of the growth region during endochondral ossification although at significantly lower level than in osteoblasts. hXBP‐1 is thus the first transcription factor described, to our knowledge, whose level of expression is modulated during the osteoblast developmental sequence in vivo. The pattern of expression of hXBP‐1 in the developing skeleton was found to be very similar to that of the genes encoding the tissue inhibitor of metalloproteinase and alkaline phosphatase throughout development. These observations suggest that hXBP‐1 may play a role in regulating the expression of tissue specific genes (TIMP, osteonectin, osteopontin, osteocalcin) expressed in osteoblasts. It is intriguing that the promoter regions of several such genes contain potential hXBP‐1 binding sites.

ISSN:1058-8388    

DOI:10.1002/aja.1001970207

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

年代:1993

数据来源: WILEY

ISSN:1058-8388    

DOI:10.1002/aja.1001970201

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

年代:1993

数据来源: WILEY