CELL KINETICS OF GROWTH CARTILAGE IN THE RAT TIBIA II. MEASUREMENTS DURING AGEING

A number of cell kinetic techniques using labelled thymidine and autoradiography have been applied to study growth cartilage in the rat tibia during ageing. No change in the duration of the synthesis phase was found from 4 to 13 weeks of age but there was a reduction in cell proliferation rate during this period. Measurements of labelling index, proliferation zone size and height of hypertrophic cells were used to calculate the growth rate of the bone from 7 days to 1 year. The results agreed well with radiographic measurements of bone growth.     

CELL KINETICS OF GROWTH CARTILAGE IN THE RAT TIBIA I. MEASUREMENTS IN YOUNG MALE RATS

Cell kinetic parameters for the proximal growth plate of the tibia have been measured in young rats. Analysis of a pulse labelled mitosis study gave values of 55 ± 40 hr for the cycle time and 6.5 ± 0.3 hr for the synthesis time in 6-week-old rats. The results of a simulated continuous labelling experiment agreed with this data and provided further information on the size and proliferation rate of the stem cell zone. Diurnal variations in mitotic index and labelling index in the tissue have been investigated.     

THE FINE STRUCTURE OF OSTEOBLASTS IN THE METAPHYSIS OF THE TIBIA OF THE YOUNG RAT

The appearance of osteoblasts after fixation with OsO₄ is described in this paper. They have the basic structures found in other types of cells. The most striking feature is the array of rough-surfaced membranes of the endoplasmic reticulum; this feature is in keeping with the osteoblast's function of producing collagen as the bone grows. The sacs formed by these membranes probably represent the protein-containing granules described by other workers using the light microscope. They contain fine fibrillary material, and similar fibrils are to be found free in the cytoplasm. These fibrils could be tropocollagen units, although fibrils recognizable as collagen by their structure are found only outside the cell. The arrangement of the cell organelles does not seem to be related to the formation of collagen, but correlation of the fine structures of the cells with the histochemical and cytochemical findings in these cells reported by other workers leaves no doubt that they are directly concerned in the production of the organic matrix. It has not been possible to show that osteoblasts influence the passage of calcium or phosphate ions from the blood to the bone matrix.     

山地麻蜥继饥饿后的补偿生长

动物继饥饿后一段时间后恢复喂食,在恢复生长阶段中常出现高于正常生长速度的补偿生长现象.有关脊椎动物补偿增长的研究主要集中在畜禽类、哺乳类和鱼类(Wilson et al.,1960;Plavnik et al.,1985;Drew et al.,1975;Pitts,1986;Kim et al.,1995),并且已在一些经济动物的饲养中利用补偿增长效应而提高经济效益.爬行动物是否存在补偿生长的现象迄今不明.本研究以山地麻蜥(Eremias breuchleyi)作为实验对象,研究其继饥饿后的补偿生长,预期为揭示爬行动物饥饿胁迫条件下的生长对策提供基础资料.     

CRYSTAL GROWTH IN RAT ENAMEL

Observations have been made, using electron microscopy and x-ray diffraction, on the changes in crystal size and shape which occur in developing rodent enamel during mineralization. Small enamel pieces isolated from ground sections of rat molars and incisors were either embedded in methacrylate and sectioned with a diamond knife for electron microscopy, or they were mounted intact on glass fibers in a Debye-Sherrer type powder camera for x-ray diffraction. By either approach it was found that the apatite crystals were very long in the c axis direction from the beginning of enamel mineralization. Morphologically, the early crystals took the shape of extremely thin, long plates arranged in such a manner that there seemed to be little room for any further length-wise growth. It was demonstrated clearly, on the other hand, that the crystals increased in both thickness and width with advancing mineralization. As a result, the thin crystal plates gradually developed into hexagonal rods, which in the most mature enamel examined measured 500 to 600 A in width and 250 to 300 A in thickness.     

日粮添加塞曼特罗（CIM）对大鼠生长胴体组成及GH水平的影响

选用２４只２月龄ＳＤ处女鼠配对分组,实验组日粮添加１０μｇ／ｇ塞曼特罗（ＣＩＭ）,试验期３０天。与对照组比较,ＣＩＭ显著提高大鼠生长速度（２７．３０％,Ｐ＜０．０１）和胴体比率,降低腰胁部脂肪重,提高腓肠肌、比目鱼肌和趾浅屈肌的鲜重和ＲＮＡ合量及ＰＮＡ／ＤＮＡ值,同时提高大鼠垂体和血清ＧＨ水平分别达３６．７０％（Ｐ＜０．０１）和２３．７７％（Ｐ＜０．０５）,降低血清脲氮含量。表明ＣＩＭ可显著促进大鼠生长,降低体脂含量,促进肌肉肥大,促进蛋白沉积。其作用机理可能还与其促进ＧＨ的合成和分泌有关。     

表皮生长因子受体在正常大鼠眼组织中的表达

采用免疫组织化学方法观察了表皮生长因子受体在正常大鼠眼组织的表达。结果发现：角膜上皮的深层细胞和角膜缘上皮细胞、部分结膜上皮细胞和结膜下结缔组织内成纤维细胞均强烈表达表皮生长因子受体。结果显示：表皮生长因子受体阳性细胞主要分布于眼表层组织。这些细胞不仅是眼组织损伤后修复、而且是多种手术能否成功和某些疾病形成中起重要作用的细胞     

刈割后两种不同体型植物的补偿式样对比研究

对比了两种不同体型植物燕麦(Avena sativa)和油菜(Brassica campestris)在不同施肥水平下的刈割反应特点。结果表明:对于燕麦而言,在不施肥条件下,3个时期的轻度刈割处理与对照相比,其生物量、总生物量、果重、果数等都有增加,但只有某些指标出现超补偿;在施肥条件下,各种刈割处理后均没有发生超补偿。并且无论施肥与否,分蘖期与拔节期的补偿指数均高于抽穗期的补偿指数。可以认为,不施肥条件下营养期轻度刈割处理较有利于燕麦的补偿生长。对于油菜而言,花蕾期轻度刈割处理后植物补偿指数最大,且施肥条件下的补偿指数高于不施肥条件下的补偿指数。比较两种植物在不同资源下补偿反应的特点,可认为因休眠芽位置及其活动方式不同而所造成的体型差异对植物的补偿反应式样有很大影响。     

THE ROLE OF NERVE GROWTH FACTOR IN THE RAMIFICATION OF SYMPATHETIC NERVE FIBRES INTO THE RAT IRIS IN ORGAN CULTURE

Small amounts of nerve growth factor (NGF) were present in the superior cervical ganglion and the iris of the rat. The observations that NGF content in each of the tissues was depleted during organ culture and that more NGF appeared in the media than was originally present in the tissues indicated that synthesis or activation of NGF had occurred in organ culture. Antibody to NGF or the depletion of endogenous NGF retarded growth of new sympathetic axons into irides in organ culture. Exogenously added NGF appeared to enhance the initiation of axonal sprouting and the rate of the ramification of nerve fibres.     

国人胫骨的测量及其性别判别分析

为积累国人资料,本文对长春、通辽两地出土的１２７副胚骨（男７１,女５６）进行了胚骨最大长、胚骨全长等２６项指标的测量,计算出胫骨中部断面指数和胚骨指数等４项指数及其分型,进行了侧别、性别及地区比较,并用胫骨最大长等７项因素进行了Ｆｉｓｈｅｒ法性别判别分析,得出５个判别式．结果显示：除个别测量项外均无显著性侧别差异,但均具有显著性性别差异,部分项目存在显著性地区差异;判别分析中判别正确率（７８．３％－８２．３％）介于美国白人与黑人之间。     

正常大鼠肺内表皮生长因子受体(EGFR)的免疫组化定位

作者以免疫组织化学技术对大鼠肺组织内表皮生长因子受体(EGFR)进行了定位研究.结果显示 EGFR 广泛分布于支气管粘膜上皮细胞、肺泡细胞、血管内皮下结缔组织和血管平滑肌细胞上。其提示 EGF 通过作用于肺组织内的特异性 EGFR 而发挥其生理和/或病理学功能。     

FAILURE TO FIND A HUMORAL FACTOR WHICH INFLUENCES THE COMPENSATORY RESPONSE AFTER RESECTION OF THE RAT SMALL BOWEL

Small bowel resection was performed in one parabiont of a parabiotic rat pair to determine whether there was a ‘humoral’ or other circulating factor present which could influence the compensatory response seen in the remainder of the small bowel. Following intestinal resection in one parabiont, there was an increase in DNA synthesis in the intestine of that member provided at least 40% of the small intestine was removed. the compensatory response seen in a resected animal was not observed in its parabiotic partner, even though an attempt was made to make the potentially responding animal more sensitive to the influence of any circulating ‘factors’ by resecting its intestine as well. The results obtained are in disagreement with the one closely related report in the literature; it is suggested that there is no good evidence for the existence of a resection-induced circulating factor with the capability of crossing a vascular anastomosis and controlling proliferation of small intestinal epithelium.     

西伯利亚鲟在高温下饥饿后的补偿生长

在高温(29±1)℃下将西伯利亚鲟幼鱼(21.61±0.03)g饥饿0(对照)、6、12和18d后恢复摄食3周, 研究摄食、生长和鱼体组成的变化。结果表明, 经过不同程度饥饿的鱼体重均显著低于对照组(P0.05), 而饥饿18d(S18组)的鱼体重显著低于对照(P0.05)。在饥饿过程中,鱼体脂肪含量和肝脏肝糖原含量下降的同时, 各饥饿组的灰分含量上升, 但仅S18组与对照差异显著(P0.05)。结果表明, 西伯利亚鲟在高温下表现出完全补偿现象, 且是通过同时提高摄食率和饲料效率来实现补偿生长的, 因此在夏季高温时对鲟鱼进行一段时间适度的饥饿可以在不影响生长和体成分的前提下节约饲料成本, 减少因过量投饵而引起的环境污染。       

THE GEOMETRY OF PERIPHERAL MYELIN SHEATHS DURING THEIR FORMATION AND GROWTH IN RAT SCIATIC NERVES

In rat sciatic nerves, a small bundle of fibers was identified in which myelin sheaths were absent at birth, appeared within 3 days, and grew rapidly for 2 wk. During this interval, nerves were removed from littermates and were sectioned serially in the transverse plane. Alternating sets of thin and thick sections were used to prepare electron micrograph montages in which single myelinating axons could be identified and traced distally. During the formation of the first spiral turn, the mesaxon's length and configuration varied when it was studied at different levels in the same Schwann cell. The position of the mesaxon's termination shifted while its origin, at the Schwann cell surface, remained relatively constant. Along myelin internodes composed of two to six spiral turns, there were many variations in the number of lamellae and their contour. Near the mesaxon's origin, longitudinal strips of cytoplasm separated the myelin layers. Thicker sheaths were larger in circumference, more circular in transverse sections, and more uniform at different levels. Irregularities were confined to the paranodal region, and separation of lamellae by cytoplasm occurred at Schmidt-Lantermann clefts. Approximate dimensions of the bundle, its largest fibers, and their myelin sheaths were measured and calculated. The myelin membrane's transverse length and area increased exponentially with time; the growth rate increased rapidly during the formation of the first four to six spiral layers and remained relatively constant during the subsequent enlargement of the compact sheath.     

RNA POLYMERASE ACTIVITY IN THE SUPERIOR CERVICAL GANGLION OF THE NEONATAL RAT: THE EFFECT OF NERVE GROWTH FACTOR

The activity of RNA polymerase in the superior cervical ganglia of the neonatal rat has been studied. The characteristics of the activity with respect to enzyme concentration, temperature, time, and ion concentrations are presented. Ionic conditions of the assay favoring polymerase I and polymerase II were each studied in the presence of specific inhibitors of DNA-dependent RNA synthesis. The K_m for GTP under either polymerase I or polymerase II conditions was found to be 10^?5M, and the relative amounts of poly(A)-containing RNA synthesized under both conditions was 4-5%. A decrease in the activity of RNA polymerase with age has been observed. The time course of increased activity following treatment of the animals in vivo or treatment of the isolated ganglia in organ culture with nerve growth factor is presented. The increase in activity observed after the administration of nerve growth factor is discussed in terms of possible mechanisms of action of nerve growth factor in this tissue.