Postembryonic development of tapeworms — source of novel phylogenetic characters for analysis of cestode evolution: comparative TEM studies

Summary Ultrastructural features of juvenile cestodes (metacestodes) can provide useful characters for phylogenetic and evolutionary analyses. Until now, however, they have been relatively little utilised (Beveridge 2001, Chervy 2002). The postembryonic development and structure of fully formed metacestodes were examined in two cyclophyllideans: Taenia parva Baer, 1926 (Taeniidae); and Sobolevitaenia verulamii (Mettrick, 1958) Korniushin, 1972 (Dilepididae). In T. parva, three developmental stages were recognized: (1) an early stage of exogenous budding at the surface of the central vesicle; (2) a stage of polycephalic cyst development accompanied by segmentation of the growing metacestode strobila and an obvious decrease in the size of the central vesicle; (3) a fully formed metacestode of the strobilocercus type with 14–24 invaginated scoleces. The tegument, scolex, subtegumental musculature of the strobilar segments, protonephridial system, calcareous corpuscles and medullary parenchyma of larvae exhibit general similarity to the same structures in adults at both LM and TEM levels. The morphogenesis of the metacestode of T. parva is compared with that of polycephalic metacestodes of other Taenia spp. (T. krepkogorski, T. twitchelli and T. endothoracica) and with other asexually multiplying metacestodes (Mesocestoides vogae, hymenolepidids and dilepidids). In S. verulamii, the body of the cysticercoid with invaginated scolex armed with a double crown of rostellar hooks was completely surrounded by the cercomer, which appears to be separated from the cyst and scolex. The surface of the suckers is covered with a thick layer of glycocalyx. Five cell types were distinguished in the sections: (1) perikarya of metacestode tegument; (2) glycolgen-storing parenchymal cells; (3) glandular-type cells with large, electron-dense secretory-like granules; (4) flame cells; and (5) calcareous corpuscle-forming cells. The surface of the cercomer is covered by elongated microvilli, which evidently differ from characteristic microtriches covering all other parts of the metacestode surface. The ultrastructure of S. verulamii evidently differs from that of the other dilepidid cestode examined to date, Lateriporus geographicus, the cyst wall of which more resembles cysticercoids of Hymenolepididae than those of Dilepididae. Concluding remarks: Ultrastructural studies on metacestodes have considerable promise for providing important new characters for phylogenetic analysis. New TEM data on a great variety of cestode species are urgently needed. Until now, this field has not been exploited in a systematic fashion. Until more comprehensive studies become available, the current data are not yet amenable to analysis.     

Fetal behavior in multifetal pregnancies studied by four-dimensional sonography

Rapid improvements in the capacity of data processing due to technological breakthroughs in processor engineering is the basis of spatial imaging. Spatial imaging is the main benefit of three-dimensional sonography and it is used for visualization of fetal anatomy in three dimensions. Modern machines are capable of performing spatial imaging in near real time, called four-dimensional sonography. Four-dimensional sonography in multifetal pregnancies can be used for detection and evaluation of intertwin contacts, because it allows simultaneous visualization of both fetuses and assessment of their motor activity. The main benefits of four-dimensional sonography include: accurate recognition of an isolated motor activity of a single fetus; distinguishing between spontaneous and stimulated motor activity; and spatial visualization of the intertwin area.     

血清瘦素在男生青春发育期的动态观察

目的 探讨血清瘦素在男生青春期发育中的作用。方法 健康男生170名，调查首次遗精时间，测定血清瘦素、睾酮、促卵泡成熟激素、黄体生成激素水平，采用多元Logistic回归模型分析男生青春期发育的影响因素；同时，连续两年观察，分析血清瘦素在青春期的动态变化。结果 末次研究已遗精组血清瘦素、睾酮、促卵泡成熟激素、黄体生成激素水平均明显高于未遗精组。多因素分析显示血清瘦素、睾酮、促卵泡成熟激素、体重为男生青春期发育的独立影响因素。初次资料分析，遗精前组血清瘦素、睾酮明显高于未遗精组。结论 血清瘦素、睾酮、促卵泡成熟激素、体重为男生青春期发育的独立影响因素，男生遗精前期血清瘦素、睾酮已有明显改变。     

Implicit memory is independent from IQ and age but not from etiology: evidence from Down and Williams syndromes

Background In the last few years, experimental data have been reported on differences in implicit memory processes of genetically distinct groups of individuals with Intellectual Disability (ID). These evidences are relevant for the more general debate on supposed asynchrony of cognitive maturation in children with abnormal brain development. This study, comparing implicit memory processes in individuals with Williams syndrome (WS) and Down syndrome (DS), was planned to verify the ‘etiological specificity’ hypotheses pertaining to the skill learning abilities of individuals with ID. Method A modified version of Nissen and Bullemer's (1987) Serial Reaction Time (SRT) task was used. The performances of three group were evaluated. The first group consisted of thirty‐two people with WS (18 males and 14 females). The second group was comprised of twenty‐six individuals with DS (14 males and 12 females). The two groups of individuals with ID were selected so that the groups were comparable as for mental age and chronological age. The third group consisted of forty‐nine typically developed children with a mental age similar to that of the groups with WS and DS. Results The two groups of individuals with ID demonstrated different patterns of procedural learning. WS individuals revealed poor implicit learning of the temporal sequence of events characterizing the ordered blocks in the SRT task. Indeed, differently from normal controls, WS participants showed no reaction time (RT) speeding through ordered blocks. Most importantly, the rebound effect, which so dramatically affected normal children's RTs passing from the last ordered to the last block, had only a marginal influence on WS children's RTs. Differently from the WS group, the rate of procedural learning of the participants with DS was comparable to that of their controls. Indeed, DS and typically developed individuals showed parallel RT variations in the series of ordered blocks and, more importantly, passing from the last ordered to the last block. Therefore, a substantial preservation of skill learning abilities in this genetic syndrome is confirmed. Conclusions The results of the present study document that procedural learning in individuals with ID depends on the aetiology of the syndrome, thus supporting the etiological specificity account of their cognitive development. These results are relevant for our knowledge about the qualitative aspects and the underlying neurobiological substrate of the anomalous cognitive development in mentally retarded people.     

Developmental spectrum of the excitotoxic cascade induced by ibotenate: a model of hypoxic insults in fetuses and neonates

Ibotenate, a glutamatergic agonist, was used to study the spectrum of excitoxic disturbances at different ages of cerebral development. Cultures of whole mouse embryo were submitted to ibotenate at E8 for 20 h: during the phase of early premigratory differentiation; ibotenate did not induce any detectable histological lesion. During migration of supragranular neurons, newborn hamsters intracerebrally injected at P0 with ibotenate display neuronal migration disorders graded from nodular heterotopias to extensive laminar heterotopias mimicking some aspects of lissencephalic and double-cortex syndromes. After completion of neuronal layer V, P0 mice injected with ibotenate exhibit laminar neuronal depopulation of layer V-VIa mimicking human micro-gyria. At P5 in mouse, after completion of neuronal migration of the cortical plate, ibotenate induces neuronal loss in all cortical layers and the formation of porencephalic cysts. This study emphasizes the dramatic role played by glutamate in brain development, in the occurrence of neuronal migration disorders in the cortex. and in grey and white matter damage.     

贵阳市婴幼儿和青少年发育调查研究 Ⅰ．骨龄研究

对贵阳市１５００名健康婴幼儿童和青少年进行骨发育的调查，根据手腕部骨Ｘ线解剖变化规律，观察每块骨从出现至成熟的过程中，骨化点的出现顺序、数量、形态和密度的改变等指标的系列变化，提出了骨发育评价标准。可供我省运动员选材、儿童少年发育咨询和临床治疗参考。     

胚胎脊髓细胞悬液植入急性成年大鼠损伤脊髓

目的：建立胚胎脊髓细胞悬液移植于脊髓损伤模型，以评价其治疗脊髓损伤的可能性。方法：４２只Ｗｉｓｔａｒ大鼠以改良Ａｌｅｎ法（５０ｇｃｍ）打击脊髓，３天后将孕１４天（Ｅ１４）ＦＳＣＳ２０μｌ植入损伤空腔，移植后２、４、６、８、１０、１２周，以光、电镜、免疫组织化学观察移植物存活、分化及其与宿主之间关系。结果：移植细胞逐渐长大。充满不规则空腔，宿主ＮＦ、５－ＨＴ、ＣＧＲＰ纤维分别出现于移植物，ＧＦＡＰ纤维于宿主移植物交界处适量存在。移植成神经细胞、成少突胶质细胞、成星形细胞的细胞器日渐完善，细胞功能活跃。复杂及多样突触与细胞连接，将上述细胞与神经纤维、胶质纤维、毛细血管网在三维空间内连接成一体，并与宿主紧密嵌合。结论：（１）成年大鼠脊髓损伤３天后植入ＦＳＣＳ可以存活。（２）移植物进入宿主后，出现再分布，继而器官样分化。（３）长、短传导束进入移植物，显示了移植物的桥作用。（４）成少突胶质细胞的神经营救作用。（５）移植区内出现多种突触，提示移植物中继作用的可能性。     

Drawing the Boundaries: Exploring gender issues in young children's classifications of work using visual representations

This study examines young children's perceptions of work through a specific example. Reception class children at an inner city school were shown pictures of the same figure washing in four different contexts, ranging from housework to paid employment, in order to examine early classifications and conceptual systems relating to the concept of work and to ascertain whether these were gender related. Individual children varied in the complexity of their ideas, but the majority had not yet began to form hierarchical classifications of work which favour paid employment. There was evidence however that some children were beginning to devalue traditional women's work, suggesting that gender stereotypes are still prevalent amongst this age group, despite efforts by the educational system to counter this.