Temporary assisting suspension suture technique for successful microvascular anastomosis of extremely small and thin walled vessels for mice transplantation surgery

Dissection and microsurgical anastomosis in small and thin-walled vessels is challenging. Temporary assisting suspension suture technique was developed to overcome those difficulties in establishing successful composite tissue allotransplantation in mice. The operations were performed in 12- to 16-week-old Balb/c mice weighing 25 to 30 grams as both donor and recipient animals. Extended vascularized groin cutaneous flaps based on the superficial epigastric vessels were used. A total of 10 groin cutaneous flaps were transplanted. Three temporary assisting suspension sutures of 11-0 nylon were placed at the 12-, 4-, and 8-o'clock positions to donor and recipient artery and vein before the anastomosis. This technique allowed atraumatic dissection of delicate and thin vessels, prevented vessel wall collapse, and facilitated adequate exposure of the lumen during placement of the permanent microvascular sutures. Thus, the microvascular anastomosis was performed in an unusual manner. The temporary assisting suspension sutures were removed just before the permanent suture was tied down. The mean operation time was 1 hour and 45 minutes with an ischemia time of 1 hour. Ninety-percent success in immediate and late-term patency rates was achieved, which was confirmed by transplant survival. This technique was proven to be useful for microvascular anastomosis in thin-walled vessels and is recommended.     

Eversion with four sutures: an easy, fast, and reliable technique for microvascular anastomosis

In this study, a microvascular anastomosing technique called "eversion with four sutures" is introduced. For microvascular anastomosis, this technique requires fishmouth incisions at both vessel ends and the completion of four sutures. In 120 Wistar-Albino rats, 120 eversion and 120 conventional anastomoses were done in 240 femoral arteries. Each rat received both treatments. Operating time, bleeding time, number of sutures used, patency rates, and pseudoaneurysm formation were analyzed statistically; healing was evaluated with both light and electron microscopy. When compared with the conventional technique using nine sutures, the eversion with four sutures technique was found to be a faster and easier method of anastomosis and as reliable as the conventional technique. Without compromising patency rates, bleeding time, or rates of pseudoaneurysm formation, anastomosis time and amount of suture material exposed to the lumen were significantly reduced when using this technique. In conclusion, the authors think that eversion with four sutures is a reliable alternative to the conventional suturing technique, especially for emergency cases that require multiple microvascular anastomoses.     

Microvascular anastomosis: vascular cuff technique

A technique is described for reinforcing and sealing a microvascular anastomosis by using a detached vessel segment as a cuff around the anastomosis. This may allow fewer microvascular sutures to be used. This would allow a simpler, less traumatic, and more rapid repair and may allow "more vessels to be repaired by more people."     

Morphological assessment of Co2-laser fusion using a flexible light guide in lymphovenous and venovenous anastomoses in experimental animals

In experiments on 13 mongrel dogs with CO2 laser supplied with flexible fiber guide there were formed 17 lympho-venous and 4 veno-venous anastomosis. There were no inadequate sealing, narrowing or aneurysm of the anastomosis. Histopathologic investigations after 3, 6-8, 13-16 days and 1 year showed that vascular walls were positioned correctly. Endothelial surface has continuous character both along the vessel as anastomosis line.     

A Systematic Review of Systematic Reviews and Panoramic Meta-Analysis: Staples versus Sutures for Surgical Procedures

Objective

To systematically evaluate the evidence across surgical specialties as to whether staples or sutures better improve patient and provider level outcomes.

Design

A systematic review of systematic reviews and panoramic meta-analysis of pooled estimates.

Results

Eleven systematic reviews, including 13,661 observations, met the inclusion criteria. In orthopaedic surgery sutures were found to be preferable, and for appendicial stump sutures were protective against both surgical site infection and post surgical complications. However, staples were protective against leak in ilecolic anastomosis. For all other surgery types the evidence was inconclusive with wider confidence intervals including the possibly of preferential outcomes for surgical site infection or post surgical complication for either staples or sutures. Whilst reviews showed substantial variation in mean differences in operating time (I² 94%) there was clear evidence of a reduction in average operating time across all surgery types. Few reviews reported on length of stay, but the three reviews that did (I² 0%, including 950 observations) showed a non significant reduction in length of stay, but showed evidence of publication bias (P-value for Egger test 0.05).

Conclusions

Evidence across surgical specialties indicates that wound closure with staples reduces the mean operating time. Despite including several thousand observations, no clear evidence of superiority emerged for either staples or sutures with respect to surgical site infection, post surgical complications, or length of stay.     

Heterotopic heart transplantation in mice

The mouse heterotopic heart transplantation has been used widely since it was introduced by Drs. Corry and Russell in 1973. It is particularly valuable for studying rejection and immune response now that newer transgenic and gene knockout mice are available, and a large number of immunologic reagents have been developed. The heart transplant model is less stringent than the skin transplant models, although technically more challenging. We have developed a modified technique and have completed over 1000 successful cases of heterotopic heart transplantation in mice. When making anastomosis of the ascending aorta and abdominal aorta, two stay sutures are placed at the proximal and distal apexes of recipient abdominal aorta with the donor s ascending aorta, then using 11-0 suture for anastomosis on both side of aorta with continuing sutures. The stay sutures make the anastomosis easier and 11-0 is an ideal suture size to avoid bleeding and thrombosis.When making anastomosis of pulmonary artery and inferior vena cava, two stay sutures are made at the proximal apex and distal apex of the recipient s inferior vena cava with the donor s pulmonary artery. The left wall of the inferior vena cava and donor s pulmonary artery is closed with continuing sutures in the inside of the inferior vena cava after, one knot with the proximal apex stay suture the right wall of the inferior vena cava and the donor s pulmonary artery are closed with continuing sutures outside the inferior vena cave with 10-0 sutures. This method is easier to perform because anastomosis is made just on the one side of the inferior vena cava and 10-0 sutures is the right size to avoid bleeding and thrombosis. In this article, we provide details of the technique to supplement the video.     

食蟹猴肾移植模型的建立

目的建立食蟹猴的肾移植模型。方法通过显微外科手术对食蟹猴进行同种异体移植,将供体肾动脉、肾静脉分别端侧吻合到受体腹主动脉、下腔静脉,供体输尿管端端吻合到受体输尿管。结果154例肾移植食蟹猴无一只在手术过程中因意外死亡;无一只因手术感染死亡;无一只因手术并发症死亡;肾热缺血时间（30±4.5）min。结论应用食蟹猴建立肾移植模型,技术成熟,方法可靠。应用此模型评价新型免疫抑制药物,进行免疫耐受、异种移植研究可为临床试验提供更为准确可靠的依据。     

MEMS-Based Handheld Fourier Domain Doppler Optical Coherence Tomography for Intraoperative Microvascular Anastomosis Imaging

Purpose

To demonstrate the feasibility of a miniature handheld optical coherence tomography (OCT) imager for real time intraoperative vascular patency evaluation in the setting of super-microsurgical vessel anastomosis.

Methods

A novel handheld imager Fourier domain Doppler optical coherence tomography based on a 1.3-µm central wavelength swept source for extravascular imaging was developed. The imager was minimized through the adoption of a 2.4-mm diameter microelectromechanical systems (MEMS) scanning mirror, additionally a 12.7-mm diameter lens system was designed and combined with the MEMS mirror to achieve a small form factor that optimize functionality as a handheld extravascular OCT imager. To evaluate in-vivo applicability, super-microsurgical vessel anastomosis was performed in a mouse femoral vessel cut and repair model employing conventional interrupted suture technique as well as a novel non-suture cuff technique. Vascular anastomosis patency after clinically successful repair was evaluated using the novel handheld OCT imager.

Results

With an adjustable lateral image field of view up to 1.5 mm by 1.5 mm, high-resolution simultaneous structural and flow imaging of the blood vessels were successfully acquired for BALB/C mouse after orthotopic hind limb transplantation using a non-suture cuff technique and BALB/C mouse after femoral artery anastomosis using a suture technique. We experimentally quantify the axial and lateral resolution of the OCT to be 12.6 µm in air and 17.5 µm respectively. The OCT has a sensitivity of 84 dB and sensitivity roll-off of 5.7 dB/mm over an imaging range of 5 mm. Imaging with a frame rate of 36 Hz for an image size of 1000(lateral)×512(axial) pixels using a 50,000 A-lines per second swept source was achieved. Quantitative vessel lumen patency, lumen narrowing and thrombosis analysis were performed based on acquired structure and Doppler images.

Conclusions

A miniature handheld OCT imager that can be used for intraoperative evaluation of microvascular anastomosis was successfully demonstrated.     

Reconstruction of the Abdominal Vagus Nerve Using Sural Nerve Grafts in Canine Models

Background

Recently, vagus nerve preservation or reconstruction of vagus has received increasing attention. The present study aimed to investigate the feasibility of reconstructing the severed vagal trunk using an autologous sural nerve graft.

Methods

Ten adult Beagle dogs were randomly assigned to two groups of five, the nerve grafting group (TG) and the vagal resection group (VG). The gastric secretion and emptying functions in both groups were assessed using Hollander insulin and acetaminophen tests before surgery and three months after surgery. All dogs underwent laparotomy under general anesthesia. In TG group, latency and conduction velocity of the action potential in a vagal trunk were measured, and then nerves of 4 cm long were cut from the abdominal anterior and posterior vagal trunks. Two segments of autologous sural nerve were collected for performing end-to-end anastomoses with the cut ends of vagal trunk (8–0 nylon suture, 3 sutures for each anastomosis). Dogs in VG group only underwent partial resections of the anterior and posterior vagal trunks. Laparotomy was performed in dogs of TG group, and latency and conduction velocity of the action potential in their vagal trunks were measured. The grafted nerve segment was removed, and stained with anti-neurofilament protein and toluidine blue.

Results

Latency of the action potential in the vagal trunk was longer after surgery than before surgery in TG group, while the conduction velocity was lower after surgery. The gastric secretion and emptying functions were weaker after surgery in dogs of both groups, but in TG group they were significantly better than in VG group. Anti-neurofilament protein staining and toluidine blue staining showed there were nerve fibers crossing the anastomosis of the vagus and sural nerves in dogs of TG group.

Conclusion

Reconstruction of the vagus nerve using the sural nerve is technically feasible.     

Mechanical remodeling of small-intestine submucosa small-diameter vascular grafts--a preliminary report

Small-intestine submucosa (SIS) is cell-free, 100-mu-thick collagen derived from the small intestine. It has been used as a vascular graft and has the highly desirable ability to be remodeled to become histologically indistinguishable from native adjacent artery. To date there has been limited reporting of its preimplantation and explant mechanical properties as a vascular graft. In this study, compliance, elastic modulus, and burst pressure were measured on preimplant-tested 5- and 8-mm SIS grafts and two 60-day remodeled grafts. Seven prefabricated grafts were implanted in the carotid (n = 7) in dogs, which were sacrificed after 55-63 days. The animals (n = 4) weighed from 22 to 27 kg. One dog received a unilateral carotid graft, and 3 dogs received bilateral carotid grafts. The fabrication technique employed hand-suturing with either nonresorbable or resorbable sutures. None of the grafts had a patency failure. Angiograms taken at 1 month and just before explantation showed uniform flow and no dilation. At the time of explantation, all carotid grafts were found to be encased in fibrous tissue. The grafts made with nonresorbable sutures showed thicker tissue growth at the suture line compared with those made with the resorbable sutures. Along the suture line, the grafts made with resorbable sutures exhibited a more natural color than those sutured with nonresorbable sutures. When the explanted carotid grafts were slit open, the lumen was white, shiny, and glistening. The grafts sutured with nonresorbable sutures exhibited small areas of fibrin and red blood cells when the suture was within the lumen. The resorbable-sutured grafts did not exhibit this response. The mean compliance (percent diameter increase for a pressure rise from 80 to 120 mm Hg) was on average 4.6% (range, 2.9%-8.6%) for the 5-mm preimplant-tested grafts. For the 8-mm preimplant-tested grafts, the increase in diameter for the same pressure rise was 8.7%, on average (range, 7.2% to 9.5%). For comparison, the small-diameter SIS graft at the time of implantation was about one half as compliant as the adjacent dog carotid artery, about 4 times more compliant than a typical vein graft, and more than 10 times more compliant than synthetic vascular grafts. The compliance measured on two 60-day carotid grafts was 10.5% and 7.2%, respectively. This is midway between the original compliance value and the compliance of a typical canine carotid artery (14%), indicating that mechanical remodeling occurred. The modulus of elasticity (E) increased exponentially with increasing pressure according to E = E0e alpha P, where E0 is the zero-pressure modulus and alpha is the exponent that describes the rate of increase in E with pressure; the unit of measure for variables E, E0, and P is g/cm2. The mean value for E0 was 4106 gm/cm2 (range, 1348-5601). The mean value for alpha was 0.0059 (range, 0.0028-0.0125). At 100 mm Hg, the mean value for E was 8.03 x 10(6) dynes/cm2 (range, 4.95-15.7 x 10(6)). For a 60-day SIS graft implant, the elastic modulus at 100 mm Hg decreased from a high value at implant time to twice that of a typical native canine carotid artery. The mean burst pressure for 5.5-mm grafts was 3517 mm Hg (range, 2069-4654). The burst pressure of the remodeled carotid grafts averaged 5660 mm Hg. The burst pressure for a typical carotid artery is about 5000 mm Hg. The results of this preliminary study complement those of previous SIS-vascular-graft studies and add a new factor, namely that the mechanical properties of the remodeled graft approach those of the vessel it replaces.     

Enzymatic activation associated with programmed fusion of the posterior interfrontal sutures in rats

Fetal rat coronal sutures in culture undergo fusion in the absence of their dura mater. Coinciding with the period of fusion are marked cellular enzymatic changes. Alkaline phosphatase, a marker of osteoblastic activity, and tartrate-resistant acid phosphatase (TRAP), a marker of osteoclastic activity, both increase significantly within fusing sutures and indicate changes in the control of bone synthesis and breakdown. Other enzymes not specifically related to bone formation or degradation also show activation within these fusing sutures. These enzymes include tartrate-sensitive acid phosphatase (TSAP), a marker of lysosomal activity; hexokinase, a glycolytic enzyme; glucose 6-phosphate dehydrogenase (G6PD), an enzyme of the pentose monophosphate shunt; and glutathione reductase, an enzyme of the antioxidant pathway.In the present study, we compared the enzymatic changes previously seen ex vivo with those occurring in vivo during the programmed closure of the posterior interfrontal suture of the rat. This suture fuses between postnatal days 10 and 30 in the rat. The sagittal suture, which remains patent during this period, was used to establish baseline enzymatic activities in a comparable midline suture. Neonatal rats were killed at postnatal days 2, 4, 5, 8, 10, 12, 15, 20, and 30, and posterior interfrontal and sagittal sutures with bone plates on either side were removed. The suture regions of the samples were isolated, dura mater was removed, and suture regions were assayed by microanalytical techniques. Activities of alkaline phosphatase, TRAP, TSAP, hexokinase, G6PD, and glutathione reductase were measured. DNA content was also assayed, and enzyme activities were expressed per amount of DNA. Three pups were killed at each time point, and three to five assays were performed per suture (posterior interfrontal or sagittal) for each time point assayed.Alkaline phosphatase and TRAP activities showed marked increases in fusing sutures compared with nonfusing controls, similar to the increases demonstrated ex vivo. TSAP and hexokinase also showed elevations in the fusing posterior interfrontal sutures, with the greatest differences predominantly during the period of fusion, comparable to the changes seen ex vivo. However, G6PD and glutathione reductase, enzymes of the antioxidant pathway, did not demonstrate the same degree of activation seen ex vivo in fusing sutures. In fact, the levels were actually higher in the patent sagittal samples for the majority of time points examined.Alkaline phosphatase and TRAP activity elevations indicated both osteoblastic and osteoclastic activation during fusion, as seen in the ex vivo phenomenon. TSAP and hexokinase increases also reflected activation in lysosomes and in cellular metabolism during fusion, paralleling the ex vivo situation. However, a less clear pattern of activation in the antioxidant pathway, in contrast to the pattern seen ex vivo, was present. These differences may reflect the different environments of sutures in vivo and ex vivo. Alternatively, oxidative stress may play a more central role in the pathologic process of induced suture fusion ex vivo than in programmed suture fusion in vivo.     

Usefulness of a first transferred free flap vascular pedicle for secondary microvascular reconstruction in the head and neck

The authors found that a previously transferred free flap vascular pedicle, distal to the first microvascular anastomosis, can be used as a recipient vessel for an additional free flap transfer. Free flap transfers were performed by using the standard procedure in patients with head and neck cancer. The mean age of the patients was 62 years. Five patients were men and three were women. A second free flap was transferred for secondary primary head and neck cancer in two cases, facial deformity in two cases, osteomyelitis of the skull in two cases, recurrent cancer in one case, and exposure of a mandibular reconstruction plate in one case. The interval between the two operations was from 4 months to 12 years (median, 21 months). All secondary free flaps were performed successfully. In two cases, the external jugular vein proximal to the previously anastomosed site was used for venous drainage. In another case, additional venous anastomosis was performed for flap congestion. It became clear that a previously transferred free flap vascular pedicle could be used as a recipient vessel for microvascular anastomosis. This is an excellent procedure for additional free flap transfers.     

杨扇舟蛾颗粒体病毒晚期表达因子的分析

【目的】本研究对杨扇舟蛾颗粒体病毒(Clostera anachoreta granulovirus,Clan GV)的晚期表达因子(Late expression factors,LEFs)进行生物信息学分析,并对Clan GV的lefs与其它杆状病毒的lefs进行对比,对鉴定lef基因和研究Clan GV的感染机制具有重要意义。【方法】使用ORF finder在线程序进行开放阅读框(ORFs)分析,BLASTP程序用于蛋白序列的同源分析,DNAStar和DNAClub生物学软件用于对序列进行处理和分析,采用BLAST在公共数据库中对序列进行比对,Clustal W Version 1.8和Gene Doc 2.7用于多序列的比对和分析,用MEGA 6.06的NJ法进行系统发育分析。【结果】Clan GV基因组包括15个lef基因,分别为ie-1、lef-2、39k、lef-11、p35、p47、lef-1、lef-6、lef-5、lef-4、dnapol、lef-3、lef-9、lef-8和lef-10。Clan GV与云杉枞色卷蛾颗粒体病毒(Choristoneura occidentalis granulovirus,Co GV)、黄地老虎颗粒体病毒(Agrotis segetum granulovirus,As GV)、苹果异形小卷蛾颗粒体病毒(Cryptophlebia leucotreta granulovirus,Cl GV)、马铃薯块茎蛾颗粒体病毒(Phthorimaea operculella granulovirus,Po GV)和苹果蠹蛾颗粒体病毒(Cydia pomonella granulovirus,Cp GV)有着较近的亲缘关系。颗粒体病毒中只有Clan GV和分月扇舟蛾颗粒体病毒含有p35。Clan GV的lef-2的转录方向不同于其它12个颗粒体病毒。γ和δ杆状病毒分别只含有7个和3个Clan GV的lef同源基因。Clan GV的lefs跟其它杆状病毒lefs的相似性较低,其中Clan GV与其它颗粒体病毒间的相似性高于Clan GV与核型多角体病毒间的相似性。Clan GV的lef-2、39k、p35、lef-5、dnapol和lef-9在启动子上游拥有TATA box;p47和lef-1在TATA下游20~40 bp处还有一个CACT基序;lef-11、p35、lef-6、lef-5、lef-3、lef-9、lef-8和lef-10这8个基因有晚期启动子基序TAAG;而p35、lef-5、lef-9和lef-10上游既有TATA又有TAAG基序。【结论】结果为研究杆状病毒的基因功能和感染机制提供了数据基础。     

The laser-assisted end-to-side microvascular anastomosis

A simple method of performing the laser-assisted end-to-side microvascular anastomosis was devised. This technique was tested on 150 Sprague-Dawley rats in two separate series of experiments. In the first, end-to-side anastomoses were performed on the iliac artery under the normal tension due to the elastic recoil of severed vessels. Four stay sutures were placed 90 degrees apart, and the intervals were "spot welded" with a low-wattage CO2 microsurgical laser unit. The patency rate (96 percent) was equivalent to that found in a control group utilizing the conventional all-suture method (92 percent), but there was a significantly higher aneurysm rate (44 versus 11 percent). In a second model, an arterial bypass with very low anastomotic tension was performed around an obstruction created in the carotid artery. This model resulted in turbulent flow but low anastomotic tension. Here the laser-anastomosis patency rate was 98 percent, versus 42 percent for the conventional all-suture method. The placement of fewer sutures in association with turbulent flow in this model may account for the improved patency rate. The avoidance of excessive tension at the anastomotic site reduced the incidence of aneurysms to a negligible level.     

Rapid novel aortic arch replacement for thoracic aortic aneurysm using three continuous sutures and a felt cylindrical collar

This report describes the novel parachute technique of open distal anastomosis at the aortic arch replacement. Two Teflon felt cylindrical collars were initially placed on the anastomotic site of the descending aorta. All four to five outer loops of the stitches used in the parachute technique were tracked by the gathering suture. The anastomotic sutures and three gathering sutures were finally pulled simultaneously. The prosthetic graft and the aortic stump with Teflon felt were safely and completely anastomosed. Surgical or hospital death and serious complications were not found. The mean anastomotic duration (circulatory arrest duration) in 16 patients was 23 minutes. Our novel technique using a Teflon felt cylindrical collar and modified continuous suturing was not only safe but also reduced the duration of anastomosis and minimized blood loss. This technique is simple and can be applied to aortic valve replacement.     

Side-to-End Lymphaticovenular Anastomosis through Temporary Lymphatic Expansion

Objective

The number of bypasses is the most important factor in lymphaticovenular anastomosis (LVA) for lymphedema treatment. Side-to-end (S-E) LVA, which can bypass bidirectional lymph flows via one anastomosis, is considered to be the most efficient bypass, but creation of lateral window to a small lymphatic vessel is technically demanding. To overcome the difficulty, we introduced S-E anastomosis through temporary lymphatic expansion (SEATTLE) procedure in S-E LVA.

Methods

This was a retrospective observational study set in a teaching hospital. Forty eight lower extremity lymphedema (LEL) patients underwent LVA. S-E LVAs were performed with (SEATTLE group) or without (non-SEATTLE group) temporary lymphatic expansion. S-E LVAs were evaluated to compare anastomosis result in SEATTLE and non-SEATTLE groups.

Results

S-E LVAs resulted in 44 anastomoses in SEATTLE group (n = 25) and 37 anastomoses in non-SEATTLE group (n = 23). LEL index reduction in SEATTLE group was significantly greater than that in non-SEATTLE group (16.5±14.5 vs. 10.9±11.8, P = 0.041). Success rate of S-E LVA in SEATTLE group was significantly higher than that in non-SEATTLE group (95.5% vs 81.1%, P = 0.040). Thirty seven of 44 (84.1%) lymph vessels in SEATTLE group were successfully dilated by temporary lymphatic expansion maneuver. All of 9 failed S-E LVAs used a lymphatic vessel with diameter of 0.35 mm or smaller.

Conclusions

The SEATTLE procedure facilitates S-E LVA by a simple and easy maneuver. When the diameter of the lymphatic vessel is 0.35 mm or smaller even after the temporary lymphatic expansion maneuver, S-E LVA is not recommended due to relatively high failure rate.     

CO2-laser radiation damage of the arterial wall

This study describes the effects of CO2 laser radiation on the histology of the normal rabbit arterial wall, using models that simulate laser angioplasty and anastomosis. Rabbit arteries were exposed to laser treatments similar to those used clinically; 40, 0.5 sec pulses of 40-60 mW, CO2 continuous wavelength laser, or a 1/2-circumferential laser anastomosis with a 60-80 mW continuous pulse. Aneurysms developed in 8 of 22 femoral, 1 of 22 carotid, and no controls at 12 week. There were small breaks in the internal elastic lamina with atrophy, loss of muscularis, "packing" of the elastica, thinning of the muscularis at the damage site, and enlargement of the arterial diameter. Aneurysms developed in one femoral and no carotid anastomosed artery. Laser anastomoses demonstrated more muscle damage and loss, with extensive scarring and a wider area of elastic loss than the controls. The intima was reestablished with focal reduplication of the internal elastic lamina. There were no histologic differences between the arteries which developed aneurysms and those which did not in either series. These results suggest that low power laser damage of the arterial wall consists mainly of destruction of the muscularis propria, with minimal damage to the elastica.     

The development of mechanical strength of surgically anastomosed arteries sutured with Dexon

The strength of surgically anastomosed arteries of the rat sutured with Dexon thread is studied. The abdominal aortas and the carotid arteries were severed, sutured and then the wounds were closed and the animal healed. After a specific period of time up to 13 months, the vessels were taken out and tested in uniaxial loading condition. The stress-strain relationship of the vessels was measured, and then the vessels were pulled to failure. It was found that the strength of the anastomosis was the lowest in about 4 months. In the first day, the force at failure was about the same as that of the control. Then the strength decreased with time, until a minimum was reached in 4-6 months. The tensile force to failure was about 25% of the control for the carotid artery and 49% of the control for the abdominal aorta. The corresponding values of the tensile stress at failure were 17 and 11%, respectively. The different percentages of forces and stresses were caused by the thickening of the vessel wall in the neighborhood of the suture line in the healing process. After 4-6 months, the strength gained again. At 13 months, the strength of the anastomosis was about the same as that of the control. The stretch ratio at failure was approximately constant through all periods.     

Importance of sucking stimulation in lactation: histological aspects of the mammary gland in the rat

The Authors refer the results of a study concerning the mammary gland of lactating rats subjected to suctional stimuli of different intensities. We made used of Wistar rats subdivided in 3 groups: Group A: each lactating 8 pups; Group B: 8 days before the birth we provided to hide the nipples of a half of the breasts with sutures like tobacco-pouch. The animals were anesthetized with ether. Each rat lactates 4 pups. Group C: They do not lactate. In the 6th day of suckling we took away the newborn from theirs mothers for 8 Hours and then we put them to lactate for other 4 hours. After this period we removed the mammary glands. We prepared this material as the routine methods for optical microscopy and after wards we stained with Hematoxylin-Eosin. Direct relationship is demonstrated between the intensity of suctional stimulus and morphologically evaluated synthetic activity.