On the appearance of monoamines in the sympathetic systems and the chromaffin tissue in the mouse embryo

Summary The early development of the sympathetic chain with adjacent ganglia and chromaffin tissue and the appearance of monoamines in these organs was mapped with the Falck-Hillarp fluorescence technique. In the 11 days embryo a few fluorescent cells are found lateral to the aorta in the thoracal region. During the following days the sympathetic chain with segmentally arranged ganglia develops. The cells have a weak to medium fluorescence intensity. A migration of fluorrescent cells ventral to the sympathetic chain can be seen in embryos 12 days old. These migrating cells will later form the prevertebral ganglia and the chromaffin tissue. At the 14 days old stage the adrenal medulla and the paraganglia can be distinguished, while the prevertebral plexa are differentiated in the 15 days old embryo.The chromaffin tissue has a brilliant fluorescence but in the neonatal stages parts of the paraganglia show a weaker fluorescence and though they have their largest extension around the 10th day of postnatal life a brilliant fluorescence can be seen only in a smaller part of the ganglia at that time. The paraganglia are reduced in adult stages.     

The development of synaptophysin immunoreactivity in the human sympathetic ganglia

Using an indirect immunohistochemical method, synaptophysin immunoreactivity (SYN-IR) has been studied in cryostat sections of stellate and thoracic ganglia in human fetuses, neonates, infants and adults. In the course of development, a progressive increase in SYN-IR in axonal terminals and around nerve cells was demonstrated. In contrast, large clusters of small intensely fluorescent (SIF) cells and paraganglionic cells increased in number in fetuses and premature neonates at 24-25 weeks. Such SIF cell clusters varied in form and often occurred at pole or subcapsular areas of sympathetic ganglia close to blood vessels or paraganglia. With increasing gestational age and during infancy, a decrease in sizes of SIF cell groups and paraganglionic cells as well as changes in their distribution were found. The results show that the amount and distribution of SYN-IR is temporally related to the maturation and functional activity of human sympathetic ganglia neurons. It was suggested that numerous SIF cells and paraganglia in human prenatal sympathetic ganglia were both indicative of incomplete cell migration and an important source of regulation of ganglionic microcirculation under the conditions of relative hypoxia and immature nervous regulation.     

Strain differences in baroceptor reflex in adult wistar kyoto rats

OBJECTIVES

A subset of normotensive Sprague–Dawley rats show lower baroreflex sensitivity; however, no previous study investigated whether there are differences in baroreflex sensitivity within this subset. Our study compared baroreflex sensitivity among conscious rats of this specific subtype.

METHODS

Male Wistar Kyoto (WKY) rats (16 weeks old) were studied. Cannulas were inserted into the abdominal aortic artery through the right femoral artery to measure mean arterial pressure (MAP) and heart rate (HR). Baroreflex gain was calculated as the ratio between change in HR and MAP variation (ΔHR/ΔMAP) in response to a depressor dose of sodium nitroprusside (SNP, 50 μg/kg, i.v.) and a pressor dose of phenylephrine (PE, 8 μg/kg, i.v.). Rats were divided into four groups: 1) low bradycardic baroreflex (LB), baroreflex gain (BG) between -1 and -2 bpm/mmHg tested with PE; 2) high bradycardic baroreflex (HB), BG < -2 bpm/mmHg tested with PE; 3) low tachycardic baroreflex (LT), BG between -1 and -2 bpm/mmHg tested with SNP and; 4) high tachycardic baroreflex (HT), BG < -2 bpm/mmHg tested with SNP. Significant differences were considered for p < 0.05.

RESULTS

Approximately 37% of the rats showed a reduced bradycardic peak, bradycardic reflex and decreased bradycardic gain of baroreflex while roughly 23% had a decreased basal HR, tachycardic peak, tachycardic reflex and reduced sympathetic baroreflex gain. No significant alterations were noted with regard to basal MAP.

CONCLUSION

There is variability regarding baroreflex sensitivity among WKY rats from the same laboratory.     

Origin and development of the epicardium in the mouse embryo

Summary The formation of the epicardium was investigated in the mouse embryo using scanning electron microscopy (SEM) in order to establish a three-dimensional perspective concerning epicardial development in mammals. The epicardium first appears as aggregates of cells scattered on the caudal surface of the ventricle and atria where these regions face the septum transversum in a 9-day-old embryo. These aggregated cells seem to have originated from the mesothelial projections extending from the surface of the septum transversum. Then, the cells of each aggregate flatten, subsequently fusing with each other to form a continuous sheet of epicardium. The fusion of aggregates proceeds in a cranial direction. Finally, the bulbus cordis and truncus arteriosus become invested by migrating cells at the cranial end of the epicardial sheet about 11 days after fertilization. The present observations are discussed in comparison with those made previously in avian embryos.     

小鼠长髓襻肾单位在髓质的分布

目的 肾髓质渗透梯度的形成与髓襻走行及转运功能关系密切,本研究拟建立长髓袢肾单位在髓质的走行规律。方法C57BL6/J小鼠3只,灌流固定后取肾组织块,树脂812包埋,垂直肾长轴连续半薄切片,从肾被膜到内髓,共得到2 000张2.5μm厚的连续切片,显微镜下获取数字图像,计算机配准,C语言编程,进而追踪26条长髓襻肾单位。结果 长髓襻肾单位来自中层和近髓质区的皮质,其髓襻襻曲分布在内髓不同水平,最深的可达肾乳头。通过数字追踪发现,在外髓内带外侧区,髓襻降支细段起始部高度盘曲走行,其盘曲部分的长度是其直线距离的2倍。在盘曲走行中,与同源的髓襻升支粗段间隔排列。最长的长髓襻升支粗段走行在外髓内带的血管丛。在外髓内带的内侧区,髓襻降支细段与髓襻升支粗段紧密相邻,直行进入内髓。结论 降支细段在外髓内带高度盘曲走行,在增加了这一节段长度的同时,也增加了这一节段的转运功能,提示此结构特征对该区域的渗透梯度形成可能产生重要影响。     

Circulatory control in hypoxia by the sympathetic nerves and adrenal medulla

1. The effects of severe arterial and primary tissue (carbon monoxide) hypoxia on cardiac output, arterial and right atrial pressures, heart rate and ventilation, have been studied in unanaesthetized normal rabbits, and in animals subjected to adrenalectomy, ;sympathectomy' (guanethidine), adrenalectomy + ;sympathectomy', and section of the carotid sinus and aortic nerves.2. In both arterial and primary tissue hypoxia the sympathetic nerves play a more important part in the normal circulatory response than the adrenal medullary hormones.3. Provided one adrenergic effector pathway remains intact, animals with intact chemoreceptors and baroreceptors tolerate both types of hypoxia well. Circulatory control during both types of hypoxia by means of sympathetic nerves alone produces relatively more peripheral vasoconstriction than is observed during reflex control through increased adrenal catecholamine secretion.4. The occurrence of tonic sympathetic activity in animals with section of carotid sinus and aortic nerves permits maintenance of a high cardiac output during hypoxia but the arterial pressure is low and there is probably less selective distribution of blood flow to the periphery than in animals with normal reflex control.5. Absence of any adrenergic activity in adrenalectomized and ;sympathectomized' animals results in a gradual fall in cardiac output during prolonged hypoxia, after an initial small rise.6. The results in guanethidine-treated animals suggest that the sympathetic discharge to the arterial chemoreceptors is a factor sustaining chemoreceptor discharge during prolonged arterial hypoxia.     

Nicotine-induced fos-like immunoreactivity in rat sympathetic ganglia and adrenal medulla

The expression of c-fos proteins (Fos) in principal sympathetic neurons and adrenal chromaffin cells was studied immunocytochemically after a single s.c. injection of nicotine (2mg/kg). One and 2 h after injection most of the adrenal chromaffin cells showed nuclear Fos-like immunoreactivity (Fos-IR). In the superior cervical ganglion more than 80% of the neuronal nuclei were Fos-IR 2-5 h after nicotine administration, whereas only 50-60% of the neurons in the hypogastric ganglion were immunoreactive at these time points. The results suggest that nicotinic receptor mediates signal transduction, which induces c-fos expression both in sympathetic neurons and in adrenal chromaffin cells in vivo.     

Different effect of methylazoxymethanol on mouse cerebellar development depending on the age of injection

Summary Methylazoxymethanol (MAM), a powerful antimitotic, has been extensively used to affect rodent CNS development. Here we show that MAM causes different effects on mouse cerebellum depending on the age of the injected pup. Sublethal doses were determined for each age. A single injection at birth permanently reduces the number of cells. In addition, the cytoarchitecture was greatly perturbed: Purkinje cells retained an immature aspect and were dispersed through the cerebellar cortex. A single dose of MAM injected into 5 day old mice also affected the number of cells but, at the level of light microscopy, the cytoarchitecture of the cerebellar cortex appeared not to be altered. Purkinje cells, however, showed some immaturity and degenerated around the 22nd postnatal day. This modulation of MAM effect appears to provide a good model for studying cerebellar ontogeny and neuronal plasticity.     

Morphology of the synovium during its differentiation and development in the mouse knee joint

Summary The prenatal and postnatal development of the mouse knee joint was investigated by transmission and scanning electron microscopy. In the prenatal stage, following the appearance of a narrow intercellular cleft between two skeletal elements on the 16th fetal day, clefting extended into the lateral synovial mesenchyme. In some regions, the extension of the cleft was very rapid, but in a certain region (future fat pad region), it was somewhat slower. Macrophage-like cells appeared in the synovial mesenchyme on the 16th fetal day, and then increased in number, and were distributed as if they were clustering around the presumptive clefting zone in the future fat pad region on the 17th–18th fetal day. This suggests that macrophage-like cells may participate in joint development, as they phagocytize and remove some kinds of solid extracellular matrix, and facilitate the cleft extension. In the early postnatal stage, scanning electron microscopic observations showed that there were two different types of cell in the synovial lining. One of them exhibited a surface morphology corresponding to that of macrophages: a spherical cell body and numerous pseudopodia. The other type of cell exhibited various cell shapes with many cytoplasmic processes extending along the synovial surface.     

小鼠前脑线粒体蛋白的增龄性变化

目的　探讨小鼠前脑不同发育阶段线粒体蛋白的表达变化。 方法　分别取妊娠12.5 d（E12.5）及17.5 d（E17.5）的胎鼠、出生2 d的新生鼠、出生3周的幼鼠和2月龄成年鼠的前脑组织,利用QRT-PCR和Western blotting检测小鼠前脑发育不同阶段中COX IV、HSP60、OGDH、PDHE1α的mRNA和蛋白表达水平。 结果　在E12.5 ~2 d的前脑组织中COX IV mRNA呈低水平表达,3周时表达量明显升高并达到顶峰;HSP60和PDHE1α mRNA在E17.5表达明显增高,OGDH mRNA则在2 d显著上升,三者表达水平均于2月达到顶峰。COX IV、HSP60、OGDH的蛋白水平从E12.5 ~3周无明显差异,但在2月时表达显著上升;PDHE1α蛋白随前脑发育其表达水平不断提高,并于2月达到高峰。此外,COX IV、HSP60、OGDH、PDHE1α mRNA与蛋白表达水平呈正相关。 结论　COX IV、HSP60、OGDH和PDHE1α可能参与了小鼠前脑发育过程且与年龄密切相关。     

小鼠胚胎气道平滑肌发育的形态学观察

目的 探讨肌特异性蛋白质在小鼠胚胎气道平滑肌的表达特点. 方法 用抗α-平滑肌肌动蛋白(α-SMA)、抗α-横纹肌肌动蛋白(α-SCA)和抗结蛋白(Desmin)单克隆抗体,对胎龄10～18d小鼠胚胎连续石蜡切片进行免疫组织化学显色. 结果 胎龄11 ～12d,前肠分隔为腹侧的气管和背侧的食管.胎龄12d,气管起始段后壁出现α-SMA阳性细胞,提示气管平滑肌开始发育,随着向气管下段延伸,α-SMA阳性逐渐减弱,肺静脉周围仅见极少量散在的α-SMA和α-SCA阳性细胞.胎龄13d,气管平滑肌α-SMA表达增强,并开始表达较弱的α-SCA和Desmin.胎龄14d,互为镜像的“C”形α-SMA阳性平滑肌表达出现在左、右支气管壁,α-SCA和Desmin的表达强度弱于α-SMA,此时肺静脉壁呈α-SMA强阳性表达.胎龄15d,α-SMA阳性平滑肌出现在细支气管壁.胎龄17～18d,平滑肌发育已延伸至终末细支气管,并显α-SMA阳性表达,而α-SCA和Desmin表达强度开始减弱. 结论 气道平滑肌发育始于胎龄12d气管上段,逐渐向下段延伸,胎龄18d,延伸至终末细支气管;Desmin的表达标志着平滑肌细胞骨架结构形成和气道平滑肌逐渐发育成熟,有助于气道平滑肌缓慢收缩功能的完善;气道平滑肌的发育早于肺静脉管壁平滑肌.     

小鼠放射状胶质细胞和小脑皮质的发育

目的探讨小鼠小脑皮质发育过程中放射状胶质细胞的分化。方法应用免疫荧光及5-溴脱氧尿嘧啶核苷(BrdU)检测技术,标记小鼠胚胎8d至生后180d小脑(57例,分为19组,每组3只)的神经干细胞、放射状胶质细胞、普肯耶细胞及颗粒细胞。结果放射状胶质细胞于胚胎13d的神经上皮出现,尔后该细胞分化为各种神经元和贝格曼胶质细胞,并在小脑皮质层状结构的形成中起着重要作用。结论放射状胶质细胞来源于神经上皮细胞,是神经细胞和神经胶质细胞的前体细胞。在小脑皮质的发育过程中,放射状胶质细胞能分化为普肯耶细胞和颗粒细胞,并为神经细胞的迁移提供路径和支架。     

Expression of the neural cell adhesion molecule (NCAM) during second- and third-molar development in the mouse

Distribution of the neural cell adhesion molecule (NCAM) during the development of the mandibular second- and third-molars of the mouse was studied by indirect immunofluorescence techniques. At the initial stage, NCAM was intensely expressed by the mesenchymal cells surrounding the dental lamina, and by the cap stage NCAM expression by the mesenchymal cells became restricted to the dental follicle. After that, in addition to the follicular mesenchyme, some cells in the basal part of the dental papilla showed NCAM-immunoreactivity for a while after the hard tissue formation had started. During root formation, the follicular cells lost NCAM first from the level of the cervical root and later from the coronal part, while an additional NCAM positive area appeared deep in the dental papilla. Even after the teeth had erupted, NCAM was expressed in the tissue surrounding the apical root and in the pulp core. During the initial and bud stages, the pattern of NCAM expression in the second and third molars was different from that in the first molar, where NCAM was found only after the late bud stage; while from the cap stage onward, it changed in the same sequence as in the first molar. The different pattern of NCAM expression implies that there is a difference in developmental events between the early stages of the first and the other two molars. On the other hand, the common sequence of NCAM expression in the tooth germs later than the cap stage suggests that NCAM plays an essential role in the formation of the basic structure of the teeth and periodontal tissues.     

小鼠短髓襻肾单位在外髓的分布

目的 肾外髓间质渗透梯度形成的机制与髓襻上皮转运功能及其毗邻关系有密切关系,本研究拟建立短髓袢肾单位在外髓的走行规律。方法C57/BL/6J小鼠3只,灌流固定后取肾组织块并树脂812包埋,垂直肾长轴连续半薄切片,从肾被膜到内外髓交界处,共得到1 200张2.5μm厚的连续切片,显微镜下获取数字图像,计算机配准,C语言编程,进而追踪来自皮质浅层和中层的120个短髓襻肾单位。结果 短髓襻肾单位的53%起于肾皮质外1/3,47%起于中间肾皮质。前者髓襻襻曲分布在外髓内带中部同一水平,其襻曲或完全由细段上皮构成,或由髓襻降支细段上皮与升支粗段上皮移行构成;来自中间皮质的短髓襻襻曲位于外髓内带内侧1/2的不同水平,其深度与其肾小球在中间皮质的深度成正比。其襻曲由髓襻升支粗段上皮构成,并在襻曲前构成约50~450μm长的髓襻降支。最深的襻曲在外髓内带弯曲走行。结论髓袢襻曲在外髓的位置及上皮类型不同,提示外髓不同区域的小管对超滤液重吸收的成分也有所区别,对外髓深部渗透梯度增高的形成产生一定的影响;而襻曲的位置和上皮构成与肾小球在皮质的位置相关,提示肾小球的滤过与肾小管的重吸收功能有整体的调节。     

Regional differentiation of sympathetic activity during hypothalamic heating and cooling in anesthetized rabbits

Summary In anesthetized rabbits immobilized with succinyl choline, the discharges of sympathetic efferents supplying cutaneous and visceral regions were simultaneously recorded. The effects of thermal stimulation of the hypothalamic region were tested on the basis of the integrated discharges. During hypothalamic heating cutaneous sympathetic activity decreased, corresponding to increased ear blood flow, while visceral sympathetic activity increased. During hypothalamic cooling there was, on the average, no significant change of regional sympathetic activity. However, in single experimental periods an increase of cutaneous and a decrease of visceral sympathetic activity was found.The observed responses of regional sympathetic activity were compared with findings about regional cutaneous and intestinal blood flow under the same thermal stimulus and further with corresponding former investigations on regional blood flow and regional sympathetic activity during spinal thermal stimulation. It is suggested by this comparison that regional differentiation of sympathetic activity represents a specific thermoregulatory response of the vasomotor system mediated by the hypothalamic thermoregulatory center.     

Expression of neural cell adhesion molecule (NCAM) during the first molar development in the mouse

NCAM, the neural cell adhesion molecule, was immunolocalized in the mandibular first molar tooth germ of the mouse. NCAM was first detected in the tooth germ of the late bud stage, where only the cells in the outer part of the condensed mesenchyme (primitive dental follicle) exhibited faint immunoreactivity. The entire dental follicle was intensely immunostained for NCAM from cap stage to the stage when root formation started. During root formation, NCAM disappeared from the follicular tissue surrounding the cervical root as well as from the part covering the crown top. This loss of NCAM proceeded in the direction of the root apex, but even after the tooth had achieved functional occlusion, NCAM was still expressed by the mesenchymal cells adjacent to the root apex. On the other hand, NCAM was negative in the dental papilla until birth. After birth, NCAM-immunoreactivity appeared in the basal portion of the dental papilla, but this NCAM-positive area gradually diminished in width during the root elongation. Instead, another NCAM-positive zone appeared in the core of the pulp during root formation. Even in the tooth that had already erupted, the pulp core contained cells that were strongly positive for NCAM immunostaining. In addition to its expression in the above two mesenchymal cell lineages, NCAM was transiently expressed by epithelial components of the tooth germ, some of the cells of the dental lamina and the enamel organ. The results suggest that NCAM participates in several processes of tooth development.     

Sympathetic nervous response to induced fall and rise of arterial blood pressure in anesthetized rabbits

Summary The baroreceptor reflex is thought to counteract both a rise and a fall in arterial blood pressure, but the evidence for this is incomplete. In 19 anesthetized rabbits, the relationship between blood pressure/aortic nerve activity and efferent sympathetic activity in renal and splanchnic nerves was therefore investigated during induced rise and fall of arterial pressure. Baroreceptor activity increased and sympathetic activity decreased with raised pressure. In contrast, reduction of baroreceptor activity during acute hemorrhagic hypotension had little or no effect on activity in the two sympathetic nerves. Following complete barodenervation, however, sympathetic activity rose on average to 238% of control values. We therefore conclude that the baroreceptor reflex mainly counteracts a rise in arterial blood pressure. Reduction of baroreceptor activity in the first few minutes of acute hemorrhagic hypotension does not lead to increased sympathetic activity. The small activity remaining in baroreceptor nerves at low pressures had a very potent sympathetic inhibitory effect.     

Bcl-2在小鼠肾脏发生发育中的表达

目的 探讨小鼠肾脏发育过程中抗凋亡蛋白Bcl-2的表达. 方法 选取胚龄16(E16d)、18d和出生后1d(P1d)、3、5、7d、14和21d的昆明小白鼠共54只,应用免疫组织化学技术并结合体视学分析方法,观察小鼠肾脏不同发育时期树脂切片上Bcl-2的表达. 结果 在小鼠肾脏发育过程中,Bcl-2的阳性表达主要出现在近端小管,从E18 d到P1 d,Bcl-2阳性表达肾小管面数密度的增长速度最快,在P7d之后,Bcl-2阳性表达肾小管面数密度的增长速度的变化不大. 结论 在肾的早期发育过程中,Bcl-2主要影响了近端小管的存活或死亡.