兔胎仔腹裂模型实验研究

目的制作兔胎仔腹裂模型，探讨肠管病理损害机制和有关胎仔实验外科的技术。方法40只孕兔随机分成三组，分别于妊娠21d、23d、25d行宫内手术，每只孕兔制作胎仔模型1～3只，包括假手术、腹腔内注射羊水和腹裂三组，至孕30d时自然产仔或行剖宫产同收胎仔模型，分别测量出生体重、小肠重量、长度、密度、厚度，并观察肠壁的组织学和细胞超微结构变化。结果孕21d组腹裂模型存活率(37．04％)显著低于孕23d组(70．59％)和25d组(70．83％)；与对照组相比，腹裂模型组胎仔体重低，小肠重量轻、长度短、密度低、厚度增加，病理组织学和超微结构也发生改变。结论胎仔外科的成功受实验对象、胎龄、麻醉、宫内操作技术等诸多因素影响；腹裂胎仔肠管大体形态和组织结构的改变是受羊水浸泡和腹壁裂口缩窄共同作用的结果。     

阿片κ受体在新生兔窒息中的作用

目的　探讨阿片κ受体在围生期缺氧导致新生兔窒息中的作用。方法　将 16只孕 30d母兔窒息后立即剖宫取出仔兔 ,随机分 3组 :新生兔窒息未治疗组 (窒息组 )、新生兔窒息中枢MR2 2 6 6治疗组 (MR1组 )及新生兔窒息外周MR2 2 6 6治疗组 (MR2组 ) ;MR1组及MR2组仔兔在分娩后 ,即刻分别从小脑延髓池及静脉注入阿片受体拮抗剂MR2 2 6 6。另取 4只无窒息母兔剖宫取出正常新生兔作为对照组。新生兔均于剖宫产后 5、10、15、30min进行呼吸、心跳、肤色、肌张力、反射评分。结果　MR1组及MR2组仔兔Apgar评分显著高于窒息组 (P<0 .0 5及P <0 .0 1) ,且MR2组评分明显高于MR1组 (P <0 .0 5 )。结论　阿片κ受体与围生期缺氧导致的新生兔窒息的发生发展密切相关     

未成熟胎兔缺氧缺血性脑损伤模型的建立

目的建立合适的早产脑损伤动物模型。方法选择孕25 d的健康新西兰白兔32只,阻断孕兔子宫血供,致胎兔宫内缺氧缺血,阻断时间分别持续30 min、35 min、37 min、40 min,对照组不阻断子宫血供。所有孕兔分别在术后24 h(孕26 d,A组)、5 d(孕30 d,B组)行剖宫产,根据阻断时间共分8亚组,每亚组4只。记录新生兔的一般状况,评估胎龄30d存活新生兔神经行为学,观察脑组织病理改变。结果 A组新生兔缺氧缺血30 min均存活,随时间延长(35~40 min),死胎率由31.0%升至100%,存活新生兔脑组织含水量、凋亡脑细胞数随时间推移逐渐增加,以上差异均有统计学意义(P均0.05)。B组新生兔,缺氧缺血35和37 min的死胎率升高为50.0%和65.7%,存活兔的体质量均低于对照组,并有不同程度的神经行为学异常,以上差异均有统计学意义(P0.05)。脑组织病理检查发现,B组脑白质损伤较A组更明显。结论孕25d持续阻断孕兔子宫血供35~37 min可造成部分死胎和宫内体质量增长迟缓,存活新生兔出现不同程度的神经行为学异常及脑白质损伤,可用于制备早产缺氧缺血性脑损伤动物模型。     

兔胎仔椎板切除术后局部的病理变化

目的：研究兔胎椎板切除术后脊髓和脊神经的局部病理改变。方法：选用胎龄24－25d的兔仔24只子宫内切除第5－7腰椎椎板。妊娠足月29－30d,剖腹观察存活的实验胎仔20只和对照组胎仔16只。观察局部改变,用光镜和电镜观察脊髓和神经节细胞的病理变化。结果：实验兔胎仔椎板缺损处有不同程度的脊膜膨出,神经与脊膜粘连。尼氏小体和线粒体,内质网肿胀和细胞膜破裂等病理损害。结论：本实验提示胎儿期椎板缺损也可发生脊膜膨出、神经粘连和神经细胞的病理损害。这些可能是脊髓脊膜膨出手术治疗效果不佳的病理基础。     

维甲酸致大鼠胚胎神经管畸形的组织形态学观察

目的 利用维甲酸制作先天性神经管畸形的动物模型已获得公认，但对于其导致神经组织错构瘤的发生却未见报道。本实验利用维甲酸口服制作大鼠神经管畸形动物模型，观察其出现神经组织畸胎瘤、脊髓裂开、脊柱裂等畸形形态学特点，探讨其发生机制。方法 利用成熟未孕的Wistar大鼠，在妊娠10dN经胃管注入维甲酸，诱导产生神经管畸形动物模型，分别在妊娠15d、17d、19d时剖宫取出胎鼠，进行实体观察、畸形统计，同时对神经管畸形进行病理形态学研究。对照组仅给予橄榄油，剖宫时间及观察项目同致畸组。结果 维甲酸致畸组共获得胎鼠99只，48．3％(48／99)孕鼠胚胎肉眼观察出现腰骶部显性脊柱裂。在48只显性脊柱裂胎鼠中，分别取不同胎龄(15d、17d、19d)各3只脊髓裂开的畸形胎鼠共9只，做石蜡切片，全部同时见到表现为多个神经管紊乱排列、骶尾部增生肿物，提示神经组织错构瘤的发生。结论 维甲酸可以干扰神经发育，导致脊柱裂、脊髓裂开和神经错构瘤的发生。     

大鼠胎仔十二指肠闭锁与肝脏胰腺在发育中的关系

目的 制作阿霉素诱导大白鼠胎仔出现先天性十二指肠闭锁的动物模型，并探讨十二指肠闭锁与伴发的胰腺、肝脏发育不良的关系。方法 Wister孕鼠10只，分为实验组7只，对照组3只，分别于妊娠第6－9d腹腔注射阿霉素1.75mg/kg或等体积的生理盐水，妊娠20d剖宫取胎仔，对十二指肠、肝脏及胰腺做解剖、电镜及光镜观察。结果 阿霉素组获取胎仔67只，十二指肠闭锁35只，占52.2%(35/67)，其中腔内闭锁1只，占2.9%(1/35)；十二指肠闭锁近远端由纤维带或胰腺组织充填者27只，占77.1%(27/35)，闭锁近远端分别为游离盲端者7只，占20.0%(7/35)。肝脏畸形22只，占32.8%(22/67)，其中21只同时存在十二指肠闭锁畸形。大体形态改变表现为部分肝分叶的缺失，尾状叶缺失14例，占63.6%(14/22)，5只尾状叶及乳突叶同时缺失，占22.7%（5／22），3例尾状叶、乳突叶也肝右叶均缺失，占13.6%(3/22)。镜下观察见部分肝小叶呈发育不良改变。胰腺异常36只，占53.7%(36/67)，其中34例同时存在十二指肠闭锁畸形。大体形态改变主要表现在胰腺体积变小，23只胰颈、体、尾部均缺如，占63.9%(23/36)，13只胰体、尾部缺如，占36.1%(13/36)。组织学观察显示部分胰腺腺泡发育不良。结论 阿霉素诱导大白鼠胎仔出现先天性十二指肠闭锁是一种可靠的模型制作方法，其十二指肠、肝脏和胰腺三者在发育过程中是相互影响的。     

可恢复性肝外门静脉高压动物模型的建立及其实验研究

目的探讨采用套管将门静脉主干部分缩窄后再去除的方法制作一种可恢复性肝外门静脉高压动物模型的可行性及有效性。方法将18只新西兰大白兔按随机数字表法分为三组,每组6只:对照组(normal control group,NC)、肝外门静脉高压组(extra-hepatic portal venous obstruction,EHPVO)和可恢复性肝外门静脉高压组(reversible extra-hepatic portal venous obstruction,r-EHPVO)。NC组仅开腹后游离门静脉主干。EHPVO组采用套管将门静脉主干部分缩窄制作肝外门静脉高压动物模型。r-EHPVO组在肝外门静脉高压模型制备2周后将套管去除。检测所有动物模型手术前后的门静脉压力、血常规和脾脏大小,并比较各组手术前后门静脉压力、红细胞、白细胞、血红蛋白及血小板和脾脏大小的变化。多组间比较采用单因素方差分析(one-way ANOVA),同一组不同时间段间的数据比较采用配对样本的t检验,以P<0.05为差异有统计学意义。结果18只动物模型的制作均成功完成。EHPVO组和r-EHPVO组的术后门静脉压力和脾脏大小均显著高于NC组,差异有统计学意义(P<0.01);EHPVO组与r-EHPVO组套管拆除前门静脉压力和脾脏大小比较,差异无统计学意义;套管拆除后r-EHPVO组门静脉压力和脾脏大小显著低于EHPVO组,但其仍高于NC组(P<0.01)。EHPVO组和r-EHPVO组的术后血红蛋白、红细胞和血小板均显著低于NC组(P<0.05);去除套管后,r-EHPVO组血红蛋白、红细胞和血小板显著高于EHPVO组,但仍低于NC组。结论采用套管将门静脉主干部分缩窄后再去除的方法制作可恢复性肝外门静脉高压动物模型是可行的,该动物模型可缓解门静脉高压状态(降低门静脉压力、脾脏大小和改善脾功能亢进状态),具有Rex手术治疗肝外门静脉高压的相似效果,能作为模拟Rex手术研究的动物模型。     

TrkA、p75NTR mRNA在肛门直肠畸形胎鼠直肠末端的表达

目的通过检测肛门直肠畸形(ARM)胎鼠直肠末端神经生长因子受体TrkA、p75NTR mRNA的表达水平,探讨ARM直肠末端肠神经系统发育情况。方法成年SD孕鼠16只。其中实验组10只,对照组6只。实验组孕鼠在孕11 d、13 d 2次给予10 g.L-1乙烯硫脲(125 mg.kg-1)灌胃,制作先天性ARM动物模型;对照组灌胃注入等量9 g.L-1盐水。2组孕鼠在孕20 d时行剖宫手术取出胎鼠,取其直肠末端并保存于-80℃冰箱;采用反转录/实时定量PCR(RT-PCR)方法检测正常胎鼠和ARM胎鼠直肠末端TrkA、p75NTR mRNA表达情况。结果 TrkA、p75NTR mRNA在正常胎鼠直肠末端的相对表达量分别是162.221±104.675,129.778±51.976,在ARM胎鼠直肠末端中表达分别是78.937±33.425,87.145±25.812,两组比较差异均有统计学意义(Pa<0.05);琼脂糖凝胶电泳显示TrkA、p75NTR基因扩增后产物cDNA片段与引物设计的扩增片段完全吻合,TrkA、p75NTR基因条带亮度对照组均高于实验组。结论 TrkA、p75NTR mRNA在ARM胎鼠直肠末端的表达异常,提示神经生长因子及受体TrkA、p75NTR可能参与ARM肠神经系统的发育。     

胎羊小肠闭锁模型的制作及宫内再通手术

对胎龄２．５～３个月的２０只绵羊胎仔制作小肠闭锁模型（正式实验１４只），同时对其中的５只实验胎仔实施宫内再通手术。模型成功率１０／１４，再通手术成功４只。对小肠闭锁模型中形成的粗大段的病理改变进行了讨论。     

羊小肠锁模型的制作及宫内再通手术

对胎龄２．５－３个月的２０只绵羊胎仔制作小肠闭锁模型（正式实验１４只），同时对其中的５只实验胎仔实施宫内再通手术。模型成功率１０／１４，再通手术成功４只。对小肠闭模型中形成的粗大段的病理改变进行了讨论。     

The impact of iatrogenic gastroschisis on pulmonary maturation in the fetal rabbit models of congenital diaphragmatic hernia

Purpose  The aim of this study was to analyze the effect of iatrogenic gastroschisis on pulmonary hypoplasia in fetal rabbits with congenital diaphragmatic hernia (CDH). Materials and methods  A total of 30 pregnant rabbits received fetal surgery on gestational day 23. A left diaphragmatic hernia was created in one end fetus (DH group) of each rabbit, and the other end fetus of the same rabbit received sham thoracotomy as control (CR group). Another 19 pregnant rabbits underwent partial resection of the diaphragm in both end fetuses on gestational day 23, and then artificial gastroschisis was performed on one end fetus (GS group) on gestational day 26, while the other end remained as control (CGS group). The fetuses were harvested on gestational day 30. The histological and morphometric evaluation of lungs and livers of the end fetuses in each group was conducted. Results  In the DH group, the lungs were hypoplastic with a decrease in the total lung weight to body weight ratio, and remarkable thickening in alveolar septa. The lung vessels showed significantly thicker arterial walls when compared with those from control fetuses. The pathological finding in the CGS group was similar to that of the DH group. The thickness of the alveolar septa and of the pulmonary arterial walls showed no significant difference among the GS group, DH group and the CGS group. The ratio of liver weight to body weight increased notably in the GS group, DH group and CGS group compared with that in the CR group. Conclusions  In the fetal rabbit models of CDH, pulmonary hypoplasia is the most significant pathological feature. Iatrogenic gastroschisis does not improve pulmonary maturation due to the active growth of the liver that herniates into the thoracic cavity.     

Metabolic quotients and oxygen extraction across the uterus of the post-term pregnant rabbit under chronic steady-state conditions

The extraction of oxygen by the uterus in the term rabbit has been found to be very high. During post-term pregnancy, the fetuses of the rabbit are approximately 40% larger, despite a reduction in placental weight of approximately 30%. The purpose of our study was to investigate the changes that occur in the maternal rabbit to allow survival of the fetus under these conditions. Post-term pregnancies were induced in 5 white New Zealand rabbits by injections of chorionic gonadotropin and progesterone on the 26th day of gestation. Catheters were placed surgically on day 28, and blood samples were taken daily from the femoral artery and uterine veins starting at day 31. Each sample was analyzed for pH, PCO2, PO2, oxygen capacity and saturation, glucose, beta-hydroxybutyrate, lactate and acetoacetate. Coefficients of extraction were calculated for oxygen and metabolic quotients were calculated for each substrate. These data are compared with those obtained for the term rabbit in previous studies. There was a significant increase in the coefficient of oxygen extraction in the post-term animals; however, the metabolic quotients across the uterus were not significantly different between the term and the post-term rabbit.     

Evaluation of diluted amniotic fluid effects on histological changes of intestine of rabbit fetus with gastroschisis

Amniotic fluid exchange is a method for prevention of intestinal damage in gastroschisis, but its techniques are different in studies. We investigated the effects of amnioinfusion exchange on histological changes of intestine and feasibility and safety of amniotic fluid exchange through central vein catheter (CVC) placed in pregnant rabbit uterus. A total of 15 pregnant New Zealand white rabbits were selected. Fetuses were randomly divided into three groups (case, control, sham). On gestational day 25, under general anesthesia with midline laparotomy, the graved bicornuate uterus was exposed. In controls, fetus abdomen was opened by a transverse incision in right lower quadrant region and intestines were eviscerated. In cases, after intestine evisceration, a central venous catheter was passed from mother skin and uterus and fixed to uterus wall. In shams, fetus was delivered on gestational day 32 and its abdomen was opened. In case group, after operation, 1–2 cc of warm saline solution was replaced through catheter every 6 h. On gestational day 32, fetuses of case and control groups were delivered. Mucosal and serosal thickness, muscle thickness, fibrin deposition, serosal collagen and ganglia were compared. Ten fetuses as shams, 7 fetuses as controls and 7 fetuses as case group were studied. Serosal thickness was 4.5 ± 3.6 μm in shams, 64.2 ± 28.7 μm in controls and 6 ± 4.1 μm in cases. Serosal thickness in control group was higher than sham (P < 0.001) and case (P < 0.002) groups. In case group, infiltration of inflammatory cells with mild edema without fibroblast infiltration was seen. Application of the CVC technique was found to be a simple procedure that effectively decreased serosal inflammatory response of intestine in gastroschisis.     

Lung growth induced by prenatal instillation of perfluorocarbon into the fetal rabbit lung

The studys aim was to evaluate whether prenatal instillation of perfluorooctylbromide (PFOB, a perfluorocarbon) into the lungs of fetal rabbits leads to increased lung growth. Hysteroamniotomy was performed in eight pregnant New Zealand white rabbits on gestational day 27. In each mother, four fetuses were randomized to undergo either 1) endotracheal intubation and intrapulmonary instillation of 1 ml PFOB, 2) intrapulmonary instillation of 1 ml 0.9% NaCl solution (saline), 3) no fetal manipulation (control), or 4) tracheal occlusion (TO). The distribution of PFOB was documented radiographically. The fetuses were born by cesarean section after 48 h, sacrificed, weighed, and their lungs excised. Fetal lung to body weight ratios (FLBW) were determined, and the lungs were snap frozen for histomorphologic analysis and lung tissue distillation. On macroscopic inspection, PFOB-filled and tracheally-occluded lungs were markedly larger than saline-filled and control lungs. Mean FLBW was higher in fetuses treated with intrapulmonary instillation of PFOB (0.037±0.009), compared with fetuses receiving saline (0.027±0.008) or the unmanipulated controls (0.028±0.008). FLBW was highest after TO (0.049±0.008). After 48 h, in-vivo radiographs did not demonstrate any residual PFOB. Average dry fetal left lung weight (in g) was much higher in the TO (0.064±0.029) and PFOB (0.062±0.016) fetuses compared with the saline (0.054±0.017) and control (0.043±0.012) groups. Alveolar architecture on microscopy was similar between all groups, although the alveolar septae appeared thicker and more cellular after PFOB treatment and TO. We concluded that prenatal intrapulmonary PFOB instillation leads to increased lung growth in the late gestation rabbit model. Although PFOB instillation resulted in lower wet FLBW than TO, the increase in dry lung weight is comparable. This novel technique may be a less invasive and less noxious treatment strategy for pulmonary hypoplasia associated with diaphragmatic hernia.     

Outcome of Intermittent Tachyarrhythmias in the Fetus

Persistent fetal tachycardias are known to have an adverse effect on fetal outcome. The outcomes of intermittent fetal tachyarrhythmias over a 12-year period at a tertiary fetal cardiology center were studied. Main outcome criteria included control of arrhythmia and death during the prenatal or postnatal period. A total of 28 fetuses had an intermittent tachyarrhythmia: 4 had intermittent atrial flutter and 24 had supraventricular tachycardia. At the time of presentation 14 fetuses were hydropic, and in 5 of the 14 an arrhythmia had not been noted prior to referral. Of the 28 fetuses, 23 were treated by drug administration to the mother. Control of arrhythmia was achieved in 10 of 11 (91%) nonhydropic fetuses and 8 of 12 (67%) hydropic fetuses, with resolution of hydrops in four cases. In the overall group there was one intrauterine death, two neonatal deaths, and one infant death, all of which occurred in the hydropic group. The arrhythmia recurred postnatally in 11 of 23 (48%) fetuses. We conclude that intermittent tachyarrhythmias may have a deleterious effect on the fetus with a significant risk of death pre- or postnatally. The fetus with nonimmune hydrops should be evaluated for a cardiac cause. Maternal antiarrhythmic therapy is indicated for intermittent fetal tachyarrhythmias. There is a high risk of recurrence of the arrhythmia during infancy, particularly if hydrops was documented during the prenatal period or if Wolff-Parkinson-White syndrome is diagnosed. Fetal echocardiography is a useful tool for diagnosis and for monitoring the progress of the fetus.     

Circulating thyrotropin in the ovine fetus: evidence for pulsatile release and the effect of hypothermia in utero

The secretion of thyrotropin (TSH) has been investigated in the chronically catheterized ovine fetus (term 145-150 days). Forty-two random plasma samples from 25 fetuses (86-149 days of gestation) were measured for TSH concentrations by radioimmunoassay. Plasma TSH concentrations were highest in the youngest fetuses [86-110 days, 3.9 +/- (SD) 5.5 microU/ml, n = 13]. Thereafter TSH concentrations declined to 0.4 +/- 0.6 microU/ml (n = 13, p less than 0.05) at 130-150 days of gestation. However, serial sampling at 15-20 min intervals for 180 min from 14 individual fetuses (91-139 days) showed that TSH was secreted in a markedly exaggerated pulsatile manner compared to that observed after birth. The mean amplitude of TSH pulses fell (p less than 0.005) from 5.9 +/- 8.1 microU/ml in the fetuses to 2.1 +/- 1.1 microU/ml in five neonatal lambs (6-22 days) and to 1.5 +/- 0.4 microU/ml in three adult nonpregnant ewes. The mean pulse frequency for the 14 fetuses was 0.7 +/- 0.3 pulses/h and was reduced (p less than 0.001) to 0.3 +/- 0.1 pulses/h in lambs and to 0.3 +/- 0.1 pulses/h in the ewes. In the neonate, hypothermia is a potent stimulus to TSH release. To examine the ontogeny of this response, the temperature of the fetus in utero (106-127 days of gestation) was lowered by circulating water (14-18 degrees C) at either a fast or slow rate through a coil placed either externally around the fetus or internally in the fetal esophagus and stomach.(ABSTRACT TRUNCATED AT 250 WORDS)     

In-utero defecation: fact or fiction?

An experimental study was performed to investigate the gastrointestinal motility and in-utero defecation by radionuclide techniques. Forty-eight New-Zealand white rabbit fetuses at 25 days' gestation (fullterm, 31 to 32 days) were divided into two groups as A (n: 24) and B (n: 24). 0.1 ml of Technetium-99m (99mTC)-HIDA (a derivative of iminodiacetic acid) containing 1 mCi of radioactivity was injected into the gluteus muscle of each fetus, which had been exposed through the uterus. This procedure was used for all fetuses and additionally surgical closure of anus by a purse string suture was performed in Group B fetuses. After replacing the fetus and uterus into the abdomen, and beginning 1 hour after injection, a live fetus was killed each hour for 24 hours. Tissue samples from the reference organs (lung, heart, stomach, kidney, bladder), liver, meconium in the proximal, mid and distal bowel, and amniotic fluid were taken. The radioactivity of each sample was determined by a gamma counter and the percentage injected dose (uptake) per gram of tissue is calculated. 99mTc-HIDA was predominantly trapped by the liver via systemic circulation and excreted into the gastrointestinal tract in both groups through which it passed into the amniotic fluid only in Group A. The very low radioactivity levels detected in the amniotic fluid of Group B originated from urinary tract and indicated the in-vivo stability of 99mTc-HIDA, thus reliability of the experimental model. Intestinal transport of a radiopharmaceutical agent in both groups and demonstrated passage into the amniotic fluid only in Group A strongly suggest that fetal defecation is a physiologic event.     

钳夹子宫血管致宫内生长迟缓幼鼠肝及脑组织变化的研究

目的　建立简便可靠的大鼠宫内发育迟缓(IUGR)模型,观察其幼鼠肝及脑重量和病理变化。方法　将大鼠分为2组:钳夹组于孕17d 行双侧子宫血管钳夹术30m in;对照组行同期开关腹术,但不钳夹子宫血管。随机获得孕21d 剖宫产及自然分娩两队。结果　剖宫产队:钳夹组幼鼠体重、肝重、脑重均明显低于对照组(P< 0.05),肝及脑组织光镜下有明显的病理形态学异常。自然分娩队:生后d6 两组幼鼠体重无明显差异(P> 0.05),但钳夹组幼鼠肝及脑重仍明显低于对照组(P<0.05),光镜下脑的异常改变部分恢复,肝的形态学改变恢复正常。结论　钳夹子宫血管法能造成IUGR模型,且IUGR幼鼠出现可测定的肝及脑损伤,生后6d 肝损伤恢复,脑损伤部分恢复