术中不同速率输注右美托咪定在全凭静脉麻醉中的量效关系研究

目的：以脑电双频指数（bispectral index,BIS）作为麻醉镇静程度指标,探讨不同速率输注右美托咪定（dexmedetomidine,DEX）对全凭静脉麻醉中丙泊酚用量,术中重要时点血液动力学及麻醉恢复质量的影响。方法：选择拟于全麻下行妇科腹腔镜手术的患者60例（ASAI～II级）,根据DEX输注速率不同随机分为四组,即D1、D2、D3和D4组,每组15例,麻醉诱导前四组均给予负荷剂量DEX0．5μg·kg-1,10min输注完毕,继而四组分别以0．2、0．4、0．6和0．8μg·kg^-1·h^-1输注速度持续输注至冲洗腹腔。四组麻醉诱导方法相同,术中以BIS作为麻醉深度指标,根据BIS值调节丙泊酚血浆靶浓度维持麻醉。记录入室用药前（T0）、DEX负荷量输注后（T1）、气腹即刻（T2）、气腹后5min（T3）、气腹后30min（T4）、解除气腹后5min（T5）、拔喉罩即刻（T6）、拔喉罩后1min（T7）时收缩压（SBP）、舒张压（DBP）、心率（HR）、丙泊酚平均用量、苏醒时间、拔喉罩时间、拔喉罩后15rainOAA／s评分、术中及术后24小时内不良反应的发生情况。结果：①D2、D3、D4组丙泊酚平均用量较D1组明显减少（P〈0．05）,D3、D4组丙泊酚平均用量较D：组明显减少（P〈0．05）。D3、D4组间差异无统计学意义（P〉0．05）。②与T0比较,Tl～T2时四组SBP、DBP、HR降低（P〈0．05）,T3～T4时D3、D4组SBP、DBP、HR降低（P〈0．05）,D1、D2组SBP、DBP无明显变化（P〉0．05）,T5～T7时四组SBP、DBP、HR降低（P〈0．05）;D3、D4组在T3～T4时SBP、DBP较D1、D2组明显降低（P〈O．05）,D1、D2两组间差异无统计学意义（P〉0．05）,D3、D4两组间差异无统计学意义（P〉0．05）。③D4组苏醒时间、拔喉罩时间、较Dlq组明显延长（P〈0．05）,D4组OAA／s评分较D1-3组明显降低（P〈0．05）。④D4组使用阿托品次数较D1-3组明显增多（P〈0．05）,四组术中使用麻黄碱次数和术后24小时内恶心、呕吐、寒战差异无统计学差异（P〉0．05）。结论：在妇科腹腔镜手术中,DEX作为全身麻醉辅助用药,负荷剂量0．5μg·kg-1,术中持续输注速率0．4μg·kg-1·h-1可以有效降低丙泊酚用量,使围手术期的血流动力学保持平稳,不延长苏醒时间和拔喉罩时间,且不良反应更少,值得临床推广应用。     

右美托咪啶复合芬太尼及七氟烷用于脑肿瘤手术的麻醉效果及对血流动力学的影响

目的:探讨右美托咪啶复合芬太尼及七氟烷用于脑肿瘤手术的麻醉效果及对血流动力学的影响。方法:择期全麻下行脑肿瘤切除术患者40例,随机分为右美托咪啶组(D组)和丙泊酚组(P组)各20例。麻醉诱导前D组静脉输注右美托咪啶0.5μg/kg,P组给予同等容量的生理盐水,均15 min泵注完成。静脉注射咪唑安定、芬太尼、顺式阿曲库铵、依托咪酯行麻醉诱导。术中均用芬太尼、七氟烷、顺式阿曲库铵维持麻醉,D组持续静脉输注右美托咪啶0.2~1.0μg·kg-1·h-1,P组给予丙泊酚3~10 mg·kg-1·h-1,调整右美托咪啶及丙泊酚用量,使BIS值维持于40~50。于麻醉用药前(基础值)(T0)、麻醉诱导气管插管前(T1)、气管插管后(T2)、切开硬脑膜(T3)、取瘤(T4)、术毕(T5)、拔气管导管时(T6)记录心率(HR)、血压(SBP、DBP)。记录手术时间、输液量、出血量、苏醒时间、拔管时间及拔管后10 min警觉/镇静(OAA/S)评分。结果:与T0比较,D组T1、T3、T4时SBP、DBP明显降低(P0.05),HR明显减慢(P0.05),但仍接近正常值,P组T1时SBP、DBP明显降低(P0.05),HR明显减慢(P0.05),T2、T5、T6时SBP、DBP明显升高(P0.05),HR明显加快(P0.05)。与P组比较,T2~T6时D组SBP、DBP明显低于P组(P0.05),HR明显慢于P组(P0.05)。D组苏醒时间、拔管时间明显短于P组(P0.05),拔管后10min OAA/S评分显著高于P组(P0.05)。结论:右美托咪啶或丙泊酚复合芬太尼、七氟烷麻醉用于脑肿瘤手术均能够提供满意的麻醉效果,右美托咪啶能抑制气管插管、拔管等引起的血流动力学反应,术后苏醒快且苏醒质量高。     

丙泊酚靶控输注麻醉维持对老年胃癌根治术患者血流动力学 及苏醒质量的影响

目的:探讨丙泊酚靶控输注麻醉维持对老年胃癌根治术患者血流动力学以及术后苏醒质量的影响.方法:ASAI～Ⅱ级行胃癌根治术的60例患者随机分为A组和B组.两组使用靶控输注麻醉诱导,起始血浆靶浓度为1μg·ml-1 1％丙泊酚泵注,A组采用靶控输注丙泊酚维持麻醉,B组采用七氟烷吸入维持麻醉.记录麻醉前(T0)、切皮后5min(T1)、手术开始30 rmin(T2)、手术开始60min(T3)、停药时(T4)、出室时(T5)各时间点的血流动力学指标的变化.记录患者术后睁眼时间、拔管时间、定向力恢复时间.结果:两组血流动力学指标(SBP、DBP、HR)在T1～T3时点迅速下降,与T0比较均有显著性差异(P＜0.05),T4时血流动力学指标(SBP、DBP、HR)开始上升,至T5时基本达到基线水平,与T0比较差异无统计学意义(P＞0.05).血流动力学指标(SBP、DBP、HR)在组间比较差异均无统计学意义(P＞0.05).两组术后睁眼时间比较差异无统计学意义(P＞0.05),A组术后拔管时间、定向力恢复时间均低于B组,相比较有显著性差异(P＜0.05).结论:丙泊酚靶控输注麻醉维持对老年胃癌根治术患者血流动力学影响小,患者术后苏醒质量高,是老年胃癌根治术患者理想的麻醉方法.     

七氟醚静吸复合麻醉对腹腔镜胆囊切除术中患者应激反应的影响

目的:探讨腹腔镜胆囊切除术中采用七氟醚静吸复合麻醉对老年患者应激反应.方法:60例拟行腹腔镜下胆囊切除(LC)的患者分为七氟醚组和丙泊酚组.七氟醚组采用七氟醚吸入和静脉泵入雷米芬太尼麻醉,丙泊酚组采用丙泊酚靶控输注和静脉泵入雷米芬太尼麻醉.分别于麻醉诱导前10min(T1)、诱导后10min(T2)、气腹后30min(T3)、气腹后60min(T4)和术后30min(T5)测定血浆肾上腺素(AD)、去甲肾上腺素(NE)和皮质醇含量.结果:两组T1和T2时血浆AD、NE和皮质醇含量无明显差异(P＞0.05).与T1时比较,两组在T3～T5三个时点血浆AD、NE含量均显著下降(P＜0.05),皮质醇含量显著上升(P＜0.05),且在T3～T5三个时点,七氟醚组血浆AD、NE和皮质醇含量与丙泊酚组比较显著下降(P＜0.05).结论:对老年LC手术患者七氟醚静吸复合麻醉可抑制交感神经兴奋,减轻机体的应激反应.     

不同剂量右美托嘧啶对胸腔镜下食管癌根治术患者心肌氧供及血流动力学的影响

目的:探讨不同剂量右美托嘧啶(DEX)对胸腔镜下食管癌根治术患者心肌氧供及血流动力学的影响。方法:选取66例我院拟行腔镜下食管癌根治术患者,随机分为三组,每组各22例:低剂量右美托嘧啶组(L组)(0.5μg/kg)、高剂量右美托嘧啶组(H组)(1.0μg/kg)、对照组(N组)(与L组和H组同等速率输注生理盐水),而后H组和L组均以0.5μg/kg/h维持输注DEX。记录各组输注前(T1)、输注后5 min(T2)、输注后10 min(T3)、输注后15 min(T4)、输注后30 min(T5)各组血流动力学指标:心率(HR)、收缩压(SBP)、平均动脉压(MAP)、每搏输出量(SV)、中心静脉压(CVP)、心排量(CO),计算HR与SBP的乘积RPP,抽取挠动脉和肺动脉血进行动脉血气分析,采用反向FICK法计算氧供(DO2)和氧耗(VO2)。结果:HR:H组和L组患者HR随时间的推移呈下降趋势,H组T3、T4、T5时间点HR较T1时间点显著降低(P0.05);与N组相比,H组和L组T3、T4、T5时间点HR显著降低(P0.05)。MAP:H组T3、T4、T5时间点MAP显著低于L组(P0.05);H组T3、T4时间点MAP显著低于N组(P0.05);H组T5时间点MAP显著低于同组T1、T2时间点(P0.05)。SBP:H组T3、T4、T5时间点SBP与L组和N组比较显著降低(P0.05);H组T5时间点SBP较同组T1、T2时间点显著降低(P0.05)。RPP:H组T3、T4、T5时间点RPP与同组T1、T2时间点和N组比较显著降低(P0.05)。DO2:H组T5时间点DO2与L组和N组比较显著降低(P0.05)。VO2:L组患者VO2T3、T4、T5时间点与组内T1、T2时间点和N组相比显著降低(P0.05);H组VO2T3、T4、T5时间点与组内T1、T2时间点和N组相比显著降低(P0.05)。结论:小剂量(0.5μg/kg)输注DEX能降低胸腔镜下食管癌患者心肌氧耗,维持血流动力学稳定,高剂量(1.0μg/kg)输注DEX降低心肌氧耗的同时会降低心肌氧供,存在一定风险,对于患有冠心病以及心肺功能低下的老年患者,建议给予小剂量输注DEX,并监测血流动力学指标,及时调整DEX用量。     

右美托咪定复合丙泊酚全麻在腰椎管减压、椎弓根钉内固定植骨、融合术中的应用

目的:观察右美托咪定复合丙泊酚全麻在腰椎管减压、椎弓根钉内固定植骨融合术中的应用价值。方法:将2015年7月至2019年8月于我院手术治疗84例腰椎退行性疾病患者按随机数字表法分为观察组和对照组,每组42例。观察组于麻醉诱导前静脉泵入0.5μg/kg右美托咪定并在术中以0.2μg/kg·h麻醉维持,对照组于麻醉诱导前静脉泵入生理盐水。对比两组麻醉诱导前(T0)、诱导后(T1)、插管后1 min(T2)和5 min(T3)、拔管1 min(T4)和5 min(T5)的心率(HR)、收缩压(SBP)及舒张压(DBP)的数值,同时记录患者的手术时间、苏醒时间、瑞芬太尼用量及12 h内吗啡用量。比较各时间点VAS评分及不良反应的发生率。结果:与T0比较,两组患者T1时HR、SBP、DBP均显著降低(P<0.05),与T1比较,两组患者T2、T3和T4时HR、SBP、DBP均显著升高(P<0.05),观察组在T3、T4和T5时HR、SBP、DBP均显著降低(P<0.05)。观察组患者各时间点VAS评分及瑞芬太尼用量和24 h吗啡用量均显著低于对照组(P<0.05),观察组患者不良反应发生率显著低于对照组(P<0.05)。结论:右美托咪定复合丙泊酚全麻能够维持术中血液动力学稳定,减少术中麻醉药物和术后镇痛药物用量,改善术后镇痛效果,且不良反应少。     

右美托咪定复合丙泊酚全麻对腰椎手术患者镇痛效果及术后恢复的影响

目的:探讨右美托咪定复合丙泊酚全麻对腰椎手术患者镇痛效果及术后恢复的影响。方法:选择我院于2015年10月~2016年10月择期行腰椎全麻手术患者92例,经随机数字表法分为观察组及对照组各46例,两组麻醉诱导方案相同,于麻醉诱导前给予观察组静脉泵入右美托咪啶,给予对照组静脉泵入生理盐水。术后均采用经静脉自控镇痛。记录两组患者麻醉诱导前(T0)、插管1 min(T1)、插管5 min(T2)、拔管后1 h(T3)及术毕(T4)的收缩压(SBP)、舒张压(DBP)、血氧饱和度(SPO_2)和心率(HR)。比较两组患者拔管后即刻疼痛及镇静情况。记录两组患者定向力恢复时间、苏醒时间、拔管时间以及吗啡使用剂量。统计两组患者不良反应情况。结果:两组患者T1时刻SBP、DBP水平较T0明显下降,对照组T3时刻SBP水平高于T0,差异有统计学意义(P0.05);观察组T1时刻DBP、SBP水平高于对照组,T3时刻SBP水平低于对照组,差异均有统计学意义(P0.05);T1、T2、T3、T4时刻观察组HR水平明显高于对照组,差异均有统计学意义(P0.05);拔管后观察组视觉模拟评分(VAS)低于对照组,而Ramasy评分高于对照组,差异有统计学意义(P0.05)。观察组吗啡使用剂量明显低于对照组,差异有统计学意义(P0.05),两组苏醒时间、定向力恢复时间以及拔管时间差异均无统计学意义(P0.05),两组不良反应发生率差异无统计学意义(P0.05)。结论:采用右美托咪定复合丙泊酚全麻对腰椎手术患者血流动力学的影响小,镇痛、镇静效果显著,术后镇痛药物使用量减少,值得临床推广。     

喉罩与气管插管全凭七氟醚吸入麻醉用于小儿眼科短小手术的效果分析

目的:对照研究喉罩与气管插管全凭七氟醚吸入麻醉用于小儿眼科短小手术的优缺点。方法:选取2012年1月至2013年12月于我院行行眼科手术的ASAⅠ~Ⅱ级小儿共80例,随机分为喉罩组(40例)和气管插管组(40例)两组,所有患儿均给予全凭七氟醚吸入麻醉,喉罩组采用喉罩通气,而气管插管组则采用气管插管通气。监测T1(诱导后下颌松弛)、T2(喉罩置入或气管插管后1min)、T3(喉罩或气管插管拔出前)、T4(喉罩或气管插管拔出后1min)四个时间点的血流动力学指标并记录两组患儿置入喉罩或气管插管的次数、手术时间、手术结束至拔除喉罩或气管插管的时间,以及可能产生的不良反应。结果:喉罩组血流动力学指标在四个测量时间点的差异均无统计学意义(P0.05);气管插管组血流动力学指标在四个测量时间点的差异均有统计学意义(P0.05),其中T2时间点均高于T1时间点,T4时间点均高于T1、T3时间点。两组患儿置入喉罩或者气管插管次数、手术时间、手术结束至拔除喉罩或者气管插管时间的差异均无统计学意义(P0.05);气管插管组患儿发生呛咳的比例高于喉罩组,差异有统计学意义(P0.05);气管插管组患儿发生呛咳的比例高于喉罩组,差异有统计学意义(P0.05)。结论:喉罩复合全凭七氟醚吸入麻醉可安全有效地应用于小儿眼科短小手术。     

三种不同麻醉方式对产妇血流动力学及新生儿的影响

目的;探讨硬膜外麻醉、蛛网膜下腔-硬膜外麻、气管插管全麻三种不同麻醉方式对剖宫产产妇血流动力学及胎儿的影响。方法:纳入行择期剖宫产产妇152例,采用随机表法将其分为硬膜外组(48例)、腰硬联合麻醉组(52例)、气管内插管全麻组(52例)。观察麻醉前正常状态时(T1)、麻醉成功后5 min(T2)、胎儿娩出时(T3)三个时间点产妇SBP、DBP、HR、SV、CO、SVR及胎儿相关指标,包括出生后1 min、5 min Apgar评分、脐动脉血pH、PCO_2、PO_2。结果:硬膜外麻、腰麻-硬膜外联合麻醉、全麻三组间麻醉起效时间有明显统计学差异(P0.05),气管内插管全麻组起效时间最快。三组间在T1时间点SBP、DBP、HR、SV、CO、SVR差异无统计学意义(P0.05)。在T2时间点,硬膜外麻、联合麻醉、全麻三组SBP、DBP、HR、SVR水平均较T1时间点明显降低,差异有统计学意义(P0.05)。T2时间点,全麻组SBP、DBP、HR、SVR水平高于硬膜外、联合麻醉组(P0.05)。T3时间点三组SBP、DBP、HR、SV、CO水平均较T2时间相比差异有统计学意义(P0.05)。T3时间点,全麻组SBP、DBP、SVR高于其他两组,心率低于其他两组,差异有统计学意义(P0.05)。三组间新生儿出生后1 min Apagr、5 min Apgar评分、脐动脉血学pH、PCO_2无统计学差异(P0.05)。三组间脐动脉血PO_2有明显统计学差异(P0.05),气管内插管全麻组脐动脉血PO_2最高。结论:三种麻醉均可以用于剖宫产术,全麻剖宫产术对产妇血流动力学影响最小,起效快,但对胎儿脐动脉血氧浓度有一定的影响。     

不同麻醉方法对二氧化碳气腹致应激激素和循环功能的影响

目的：观察比较全麻和全麻复合硬膜外麻醉在腹腔镜胆囊切除术（LC）时,对CO2气腹致应激激素和循环功能的影响。方法：40例LC患者随机分为全麻组（A组,n=20）和全麻复合硬膜外麻醉组（B组,n=20）,连续监测SBP、DBP、MAP、HR、ECG、SpO2、PETCO2,记录两组患者麻醉前（T1）、插管后（T2）、气腹后10min（T3）、气腹后20min（T4）和放气后10min（T5）的SBP、DBP、MAP、HR、同时抽静脉血测定血糖（Glu）、血浆皮质醇（Cor）、促肾上腺皮质激素（ACTH）和血管紧张素-Ⅱ（AT-Ⅱ）。结果：T1时两组所有检测值比较差异无显著性（P＆gt;0.05）;在T2、T3、T4、T5时A组SBP、DBP、MAP值明显升高,B组较基础值下降,组间差异显著（P＆lt;0.05）;气腹建立后A组HR,Glu、Cor、ACTH、AT-Ⅱ明显上升（P＆lt;0.05）,B组无显著变化（P＆gt;0.05）,（除ACTH外）组间差异显著（P＆lt;0.05）。结论：全麻复合硬膜外麻醉用于LC手术时,能相对更好的的抑制CO2气腹所致应激激素的升高,使循环更稳定。     

Ectogenesis and the case against the right to the death of the foetus

Ectogenesis, or the use of an artificial womb to allow a foetus to develop, will likely become a reality within a few decades, and could significantly affect the abortion debate. We first examine the implications for Judith Jarvis Thomson’s violinist analogy, which argues for a woman’s right to withdraw life support from the foetus and so terminate her pregnancy, even if the foetus is granted full moral status. We show that on Thomson’s reasoning, there is no right to the death of the foetus, and abortion is not permissible if ectogenesis is available, provided it is safe and inexpensive. This raises the question of whether there are persuasive reasons for the right to the death of the foetus that could be exercised in the context of ectogenesis. Eric Mathison and Jeremy Davis have examined several arguments for this right, doubting that it exists, while Joona Räsänen has recently criticized their reasoning. We respond to Räsänen’s analysis, concluding that his arguments are unsuccessful, and that there is no right to the death of the foetus in these circumstances.     

On the diversity of the Cladocera in the tropics

The mythical concept of an impoverished tropical cladoceran fauna is refuted. On a planetary scale, around half of the cladoceran species presently known occur exclusively in the tropics-subtropics, often with considerable restriction to particular geographical subzones. On a regional (political) scale, the situation is often unclear because of the continued fragmentary nature of studies, and because political units are not a good basis for biogeographical comparisons. At the finest level of resolution (lake-perlake comparisons), there appears to be an upper limit of c. 50 cladoceran species per individual lake. No significant difference between lakes in the temperate zone and in the tropics could be established here. Daphnia is largely absent from the tropics, but is replaced by more Sidids, Moinids, and Bosminids, such that the average cladoceran community in the limnetic zone of a tropical lake is not characterized by less species but rather by lower population densities. This, in turn, is considered a consequence of higher prevalent predation levels in the tropics.     

Tubular networks in the terminal endings of the visual receptor cells in the human,the monkey,the cat and the dog

Summary A tubular network was found in the terminal endings of the visual receptor cells in the human, the monkey (Macaca mulatta), the cat and the dog. These tubules are arranged in close groups in the vicinity of the synaptic lamellae and the invaginated dendrites. According to the form, diameter, density of the tubules and to the consistence of the network formed by them one can distinguish at these places an initial type (type I), a transitory (type II) and a vesicular one (type III). In the the type III branching, bizarre forms are frequent. The diameter of all the tubules reaches 500–600 Å, their density and walls being the same as in the synaptic vesicles.Similar networks also occur in the axons of the visual receptor cells of the monkey.

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Zusammenfassung In den Endigungen der Photorezeptorzellen von Mensch, Affe (Macaca mulatta), Katze und Hund kommen aus Tubuli bestehende Komplexe vor. Organellenartig in geschlossenen Gruppen angeordnet, liegen sie in Nähe der synaptischen Lamellen und der invaginierten Dendriten. An diesen Stellen kann man nach Form, Durchmesser, Dichte und Konsistenz der von den Tubuli gebildeten Komplexe drei Typen unterscheiden: 1. einen initialen (Typus I), 2. einen Übergangstypus (Typus II) und 3. einen vesiculären Typus (Typus III). In letzterem kommen häufig verzweigte, bizarre Formen vor. Der Durchmesser sämtlicher Tubuli erreicht 500–600 Å. Ihre Dichte und ihre Wand gleicht denen der synaptischen Vesikel.Ähnliche Komplexe fanden wir auch in den Axonen der Photorezeptorzellen vom Affen.

     

Assessing the Physiological State of the Fucoids from the Barents Sea Littoral by the End of the Polar Night

Methods of amperometry and potentiometric titration were used to follow dark respiration (DR) and apparent photosynthesis (AP) in the fucoids Ascophyllum nodosum (L.) Le Jol, Fucus vesiculosus L., and F. serratus L. from the Barents Sea littoral by the end of the 40-day-long polar night. The macroalgae were shown to manifest species-specific low rates of photosynthesis and respiration. However, in spite of their low photosynthetic status due to the effects of subzero temperature and prolonged low or zero illumination, the macroalgae have been able to restore DR and AP to the initial level already by the day 9; the ability to restore AP depended on the level of illumination. The study of the changes in the carbonate–bicarbonate system in the light and darkness demonstrated that the macroalgae grown in darkness, in contrast to those grown in twilight, could absorb bicarbonate in darkness; however, they lost this capacity after two-day-long illumination at an irradiance of 7 mol/(m² s). Bicarbonate uptake in darkness and the capacity to restore the systems of photosynthesis and respiration in fucoid cells are discussed in the context of algal energy metabolism under the polar night conditions.     

Arranging the elements of the potassium channel: the T1 domain occludes the cytoplasmic face of the channel

The voltage-gated potassium channel is currently one of the few membrane proteins where functional roles have been mapped onto specific segments of sequence. Although high-resolution structures of the transmembrane portions of three bacterial potassium channels, the tetramerization domain and the cytoplasmic ball are available, their relative spatial arrangement in mammalian channels remains a matter of ongoing debate. Cryo-electron microscopic images of the six transmembrane voltage-gated Kv channel have been reconstructed at up to 18 Å resolution, revealing that the T1 domain tetramerizes and is suspended below the transmembrane segments. However, the resolution of these images is insufficient to reveal the location of the third piece of the puzzle, the inactivating ball domain. We have used the aberrant interactions observed in a series of chimæric channels to establish that an assembled T1 domain restricts access to the cytoplasmic face of the channel, suggesting that the N-terminal ball and chain may be confined in the space between the T1 domain and the transmembrane portion of the channel.     

Feeding the vertebrate retina from the Cambrian to the Tertiary

The retina of the vertebrate eye is metabolically active and requires nutritive support. During the last 540 million years it has evolved into forms as complicated and nutritionally demanding as those found in avian or primate eyes. Diffusion from the choroid is generally able to supply the metabolic needs of thin retinae. However, when the thickness exceeds the limits of diffusion, structures are needed to supplement the vascular supply from the choroid. These supplemental nutritive devices include the choroidal gland, the falciform process and preretinal vascular plexus of fish, the conus papillaris of lizards, the pecten oculi of birds, the intraretinal vessels of mammals and a few novel systems that remain difficult to classify. These vascular systems are among the most variable features of the vertebrate eye. Here, we review classical and recent findings regarding such retinal nutrition systems, propose a three category classification for them based on histologic origins and speculate on the evolutionary forces which drove their development.     

Observations on the permeability of the choriocapillaris of the eye

Summary The choriocapillaris is a fenestrated capillary bed located posterior to the retinal pigment epithelium. It serves as the main source of supply to the photoreceptors, retinal pigment epithelium, and other cells of the outer retina. The permeability of these capillaries to intravenously injected ferritin (MW — approx. 480,000; mol. diam. 11 nm) was examined in the mouse, rabbit, and guinea pig, each of which is characterized by a different type of retinal vascularization. In all three species, the bulk of the ferritin remained in the capillary lumina, where it appeared to be blocked at the level of the diaphragmed fenestrae. Some ferritin was present in endothelial cell vacuoles. The results confirm previous work on the rat choriocapillaris and indicate that the barrier function of the choriocapillary endothelium is present even among species in which the retinal circulation differs significantly.Supported by NIH grant EY03418     

Separation of the pineal vesicle from the wall of the third ventricle during the post-hatching development of the chicken

Summary According to light- and electron-microscopic observations the pineal organ of the 3-day-old chicken consists of a prominent end vesicle and a tapering parenchymal stalk. During this stage the pineal lumen is in open communication with the third ventricle. However, in the 40-day-old chicken, which still possesses a well-developed end vesicle, the proximal portion of the pineal stalk displays regressive changes leading to local fragmentation. At this stage the pineal stalk is reduced, and the pineal lumen is missing. In 1-year-old chickens the parenchyma of the proximal portion of the stalk is further diminished, and in 3-year-old domestic fowl is completely displaced by bundles of collagenous fibers, only some nerve fibers being present. This post-hatching pineal development may reflect the sequence of changes leading from pineal sense organs to pineal glands.This work was supported by a grant-in-aid for Scientific Research from the Ministry of Education, Science and Culture of Japan