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关键词： inflammation   embryonic liver   embryonic lung   placenta  

摘要： After 2 days of aseptic inflammation in pregnant rats the number of hematopoietic lineage cells in the embryonic liver decreased, while proliferative activity of cells in the embryonic lung increased. Degenerative changes were noted in the placenta.

ISBN: (纸本)753800355X

关键词： Animals   Arteriosclerosis   Connective Tissue   Connective Tissue Cells   Humans   Kidney Diseases   Mice   Mice   Knockout   Platelet-Derived Growth Factor   Pulmonary Fibrosis   Research Support   Non-U.S. Gov't   Research Support   U.S. Gov't   P.H.S.  

摘要： Studies of PDGF-A, FDGF-B and PDGF receptor-beta knock-out mice have revealed critical functions for the PDGF-PDGF receptor signaling systems in the ontogeny of connective tissue cells: the mesangial cells of kidney glomeruli and the alveolar smooth muscle cells (SMC) of the lung. The phenotypes of the PDGF mutant mice have also shed light on the identity and functions of these cell types, as well as revealed analogies suggesting that common morphogenetic principles have evolved for use in different organs, involving related growth factors and cell types. Although the lethality of PDCF knock-out mice has not allowed an investigation of the role of PDGF ir. SMC of the vessel wall, regulation of PDGF and its receptors in adult vessels following injury is consistent with a role for PDGF in the fibroproliferative response in the intima that occurs as part of the pathogenesis of atherosclerosis. PDGF modulation of connective tissue synthesis may thus be critical to connective tissue phenotype and proliferation in both embryogenesis and pathogenesis.

关键词： Orthopedics  

摘要： Normal growth and development of the skeleton require the presence of viable, actively contracting skeletal muscle throughout the fetal period. A chick embryo model of midgestation chemical paralysis and secondary muscle atrophy was used to test the hypothesis that functioning muscle stimulates the growth of long bones by influencing the proliferation, differentiation, and hypertrophy of chondrocytes in cartilage of the epiphysis and growth plate. Paralysis did not alter the overall developmental stage df the long bone or the organization of the growth plate. Compared with controls, however, uptake of bromodeoxyuridine in the paralyzed chick was reduced by 27-55% in the chondroepiphysis and uppermost zone of the tibial growth plate, indicating reduced proliferation of chondrocytes. A specific reduction in the size of the proliferative zone and a reduced number of proliferating cells were also observed. By contrast, in the second, post-proliferative zone of the growth plate, the height of the zone was unchanged and its area was only slightly reduced compared with controls. Finally, median hypertrophic cell profile area, a measure of cell size, was nor significantly affected by paralysis, although frequency analysis revealed modest numerical reductions in the population of the largest hypertrophic chondrocytes in the paralyzed group, These data suggest that the role of functioning fetal muscle in maintaining proper skeletal growth may be mediated primarily through specific stimulation of the recruitment or proliferation of of immature chondrocytes, or of both.

关键词： rats   developmental biology   extracellular space   neural pathways  

摘要： In the embryonic CNS, preformed pathways precede the growth of axonal fasciculi [Katz M. J. and Lasek R. J. (1980) Cell Motil. 1, 141-157;Katz M. J. er al. (1980) Neuroscience 5, 821-833]. What are the developmental events that lead to the elaboration of these preformed pathways? To answer this question, we investigated the organization of the primitive neural tube and more particularly the arrangement of the early-generated cells using [H-3]thymidine autoradiography or bromodeoxyuridine. Our data suggest that the position of early-generated cells might be involved in the setting of such pathways. In the brain stem of E12(0) (12 days and 0 h) and E12(15) rat embryos, the first-generated cells were organized into three longitudinal columns associated with glycoconjugate-rich extracellular spaces in the adjacent primitive marginal layer. Also, axons traced with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) were contiguous to the early-generated cellular columns and represented the primordium of the medial longitudinal fasciculus, the lateral longitudinal tract and the mesencephalic trigeminal tract. Our results show a correlation between the organization of early-generated cells, likely neurons, and the pattern of extracellular spaces in the marginal layer where axons grow. It has been reported in the literature that neurons produce elements of the extracellular matrix such as growth-modulating molecules or space-creating molecules. We therefore suggest that the position of early-generated neurons could be involved in the elaboration of a template for the setting of some major longitudinal tracts during embryonic development of the brainstem. (C) 1997 IBRO.

关键词： 医药、卫生   基础医学   习题、试题及题解  

ISBN: (纸本)753800355X

关键词： 鼻中隔   胚胎发育   偏曲   组织形态学  

摘要： 目的：为探讨鼻中隔偏曲的原因以及为临床鼻科医生对先天性鼻中隔偏曲的早期检查和矫正提供组织形态学依据。方法：观察８２例１２～４０ｗ胎儿鼻中隔发育的组织形态学特点。结果：①先天性鼻中隔偏曲发生率为３３％，其偏曲程度较轻，主要位于鼻中隔的垂直板中央区和垂直板与犁骨交界处；②筛骨垂直板的上下径生长大于犁骨，且骨化时间晚，至出生时仍未骨化；③筛骨垂直板中央区为鼻中隔最薄处；④犁骨沟呈“Ｕ”形，宽而深。结论：①鼻中隔偏曲在母体内即可发生，且主要发生在鼻中隔中部，而前部易受后天性损伤而致偏曲；②筛骨垂直板与犁骨之间的生长不平衡是导致先天性鼻中隔偏曲的重要原因，即为主动性偏曲。

关键词： 克劳茨基棉   组织培养   胚胎发生   器官分化   棉花  

摘要： 用扫描电镜观察克劳茨基棉不同类型的愈伤组织和胚状体。结果表明克劳茨基棉花药诱导产生的愈伤组织可分为胚性愈伤组织和非胚性愈伤组织两类；克劳茨基棉组织培养植株再生存在着两条途径，即胚胎发生途径和器官分化途径；胚状体表面光滑，不定芽表面密生着大量的表皮毛。本文提出了在扫描电镜下鉴别胚状体、不定芽。

关键词： 组织胚胎学   动情周期   共培养   胚泡着床   体外培养成熟   卵母细胞   细胞外基质   妊娠初期   子宫内膜   上皮细胞  

关键词： Animals   Beak   Calcification   Physiologic   Chick Embryo   Culture Techniques   Periosteum   Research Support   Non-U.S. Gov't   Research Support   U.S. Gov't   Non-P.H.S.   Toes  

摘要： Reliability in a culture system is essential if data derived from that system are to have meaning. We are using cultures of 17-d chick embryo periostea to study ionic and other controls of bone development. The ectodermal surfaces of periostea removed from the calvaria of such embryos provide a rich, relatively pure source of osteoblast precursors. When placed into culture, mineralized bone develops within 6 d. This bone is identical both in structure and ultrastructure to the intramembranous bone formed in vivo. While the cultures are quite reliable, we found that occasionally an explant cultured in complete medium did not mineralize. Such rare failures confound our experiments. We wanted to know whether failure to mineralize was random or was due to a property of the embryo used for that explant.