Behavioral and activity assessment of laboratory mice (Mus musculus) after tail biopsy under isoflurane anesthesia

Contemporary laboratory animal guidance suggests that tail biopsy of laboratory mice can be performed before 21 d of age without anesthesia, whereas older mice must receive anesthesia before biopsy. Our objective was to determine whether administration of isoflurane anesthesia before tail biopsy produced a measurable effect on the behavior of mice (n = 196). We evaluated C57BL/6 and BALB/c mice at 21 to 24 (weaning), 28 to 31 (delayed weaning), and 42 to 45 (adult) d of age. Mice were observed at the time of biopsy and then twice within the first hour after a sham or tail biopsy. Anxiety-like responses were assessed by using an elevated plus-maze. Activity was evaluated remotely for 120 min. Isoflurane did not diminish acute responses to tail biopsy in mice 31 d or younger compared with sham-biopsied animals but had a significant effect in C57BL/6 biopsied adult mice. In addition, mice of all ages and strains that received anesthesia, regardless of biopsy, spent more time in the enclosed maze arms and had decreased activity up to 5 h after isoflurane exposure. Although tail biopsy should be performed in young mice to avoid transection of distal mature vertebrae, our experimental paradigm indicates that isoflurane anesthesia does not appreciably enhance wellbeing over that of mice biopsied without anesthesia at weaning ages. The influence of inhaled isoflurane was demonstrable and indicated that acute and prolonged alterations in anxiety and activity must be considered when interpreting the impact of anesthesia on tail biopsy across various ages and strains of laboratory mice.

Intestinal resection and anastomosis in neonatal gnotobiotic piglets

We describe a surgical method for ileal resection and anastomosis in newborn germfree piglets that was undertaken to establish a model that can be used for immunologic research and other applications. A preliminary experiment indicated that neonatal piglets with resection of approximately 60 cm of their ileum (removal of approximately 90% of the continuous ileal Peyer patches; group A) and those in which the ileum was transected (group B) could be maintained germfree for 35 d, colonized with defined gut flora, and maintained in a clean room until 70 d of age. In the final study, 12 piglets (4 each for groups A and B and 4 untreated controls), were monitored for postoperative feeding behavior, malaise, evidence for contamination with pathogenic bacteria, and weight gain. All surgical animals were free from incidental contamination from pathogens and environmental organisms with atypical colony types for 35 d. Two piglets in group B died postoperatively (1 during the preliminary experiment and 1 during the final study). Control (group C) piglets gained significantly more weight than did those in group A. These studies demonstrated that surgical resection of the ileal Peyer patches under germfree conditions can be accomplished successfully without compromising piglet health or introducing pathogens and with only a modest reduction in weight gain.

Laboratory guidelines for animal care

Animal research is a controversial subject because of the ethical and moral implications of using unwilling research subjects in potentially painful or distressful procedures usually ending in euthanasia. As such, it must be conducted in a compassionate and responsible manner geared toward maximizing the animals' quality of life prior to and during experimentation. Because of its contentious nature, the conduct of animal research is highly regulated at the federal, state, city, and institutional levels. It is essential that researchers acquire a working knowledge of the procedures and regulations in order to protect themselves and their staff from occupational hazards as well as protect their labs from criticism or attack from animal rights organizations. Perhaps the best way to protect from the latter is to avoid inadvertent instances of noncompliance with their research protocol or applicable regulations. Regulatory noncompliance can also have serious negative consequences on investigators' research ranging from temporary suspension of their protocols to loss of funding or principal investigator status. To minimize such events, it is advised that researchers build positive and collaborative relationships, trust and rapport with key institutional players, such as the veterinary staff, the Institutional Animal Care and Use Committee (IACUC), and top administrators. Guidance is provided regarding the appropriate handling of regulatory noncompliances.

A system for implanting laboratory mice with light-activated microtransponders

The mouse is the most commonly used laboratory animal, accounting for up to 80% of all mammals used in research studies. Because rodents generally are group-housed, an efficient system of uniquely identifying individual animals for use in research studies, breeding, and proper colony management is required. Several temporary and permanent methods (for example, ear punching and toe clipping) are available for labeling research mice and other small animals, each with advantages and disadvantages. This report describes a new radiofrequency identification tagging method that uses 500-μm, light-activated microtransponders implanted subcutaneously into the ear or tail of mice. The preferred location for implanting is in the side of the tail, because implantation at this site was simple to perform and was associated with shorter implantation times (average, 53 versus 325 s) and a higher success rate (98% versus 50%) compared with the ear. The main benefits of using light-activated microtransponders over other identification methods, including other radiofrequency identification tags, is their small size, which minimizes stress to the animals during implantation and low cost due to their one-piece (monolithic) design. In addition, the implantation procedure uses a custom-designed 21-gauge needle injector and does not require anesthetization of the mice. We conclude that this method allows improved identification and management of laboratory mice.

A novel type of implantable and programmable infusion pump for small laboratory animals

INTRODUCTION

The iPRECIO (Primetech Corporation, Tokyo, Japan) is a new form of pump for infusing small laboratory animals. The key features of the iPRECIO are that it can be implanted within the animal, it is refillable, and it is programmable. The infusion start-points and end-points are adjustable, infusion rate can be altered, and the infusion solution can be changed after the pump is implanted. In order to confirm the precision of the iPRECIO, in vivo and in vitro experiments were employed.

METHODS

In the in vitro experiment, at the excretion rate of 1 microl/h for 336 h, 15 microl/h for 96 h, and 30 microl/h for 120 h, the decrease in each pump weight was used to estimate the actual excretion volume. In the in vivo experiments, the iPRECIO was chronically implanted in rats, angiotensin II was infused, and arterial pressure (AP) was monitored.

RESULTS

In the in vitro experiment, the volume of solution excreted from the pump increased with time, and the volume excreted matched the programmed volume. The infusion rate also changed at the scheduled time. In the in vivo experiment, AP increased and decreased on schedule, and a dose-dependent pressor response to angiotensin II occurred. Furthermore, after exchanging saline with angiotensin II, AP increased and decreased on schedule.

DISCUSSION

Present data of the in vitro and in vivo experiments indicates that the iPRECIO worked precisely, making it suitable for a variety of experiments involving small laboratory animals.

Anesthetic experimental device for small animal

PURPOSE

The difficulty to anesthetize small laboratory animals with vaporizer prompted us to go in search of new materials, and create new techniques. The improved equipment of anesthesia we looked for should be low cost, practical, versatile, and its management serve ethical, teaching, and research purposes.

METHODS

The new components of the equipment were: the vaporizer, the unidirectional valve, the glass cylinder filled with water, the flow guidance y-shape tube, the flow regulators, the mask modifications, and another free airway for emergency occurrence. A test was done with 30 Wistar rats, Rattus norvegicus albinus, divided into three groups with 10 rats for each one. Groups 1, 2 and 3 were anesthetized with Ether, Halothane and Sevoflurane respectively, using the new gadget. The anesthetic induction time, the breathing rhythm alteration during an anesthesia pre-established time (10 minutes), and the recovery time were observed.

RESULTS

The equipment enabled an easy handling, and fulfilled a larger safeness and stability during the induction and anesthetic management. The test showed it was possible to make use of several anesthetic agents.

CONCLUSION

The device is effective, and turns the anesthesia procedure into a very easy practice with low-cost. It should be recommended for experimental surgery, teaching and research.

Intraoral cheek fistulae: a refined technique

Taste reactivity testing (TRT), which entails infusing a solution into the oral cavity of subjects, is used across a wide range of studies. For laboratories inexperienced in the conventional technique of implanting cheek fistulae, the surgery can be problematic for both the subjects and the experimenter. We have proposed a refined method for fistulae implantation that is less invasive, thereby reducing the pain and distress of the animals. Using this refined technique, we were able to replicate the findings of previous TRT studies, namely that a high dose of lithium chloride produces an increase in aversive and a decrease in ingestive orofacial and somatic responses. Using indices of health, we demonstrate that unlike animals with the conventional method of fistulae implantation, subjects that receive the refined technique regain their pre-surgery body weights rapidly and show no physical signs of discomfort. Additional advantages of the refined technique are discussed.

The impact of different blood sampling methods on laboratory rats under different types of anaesthesia

Rats with implanted telemetry transponders were blood sampled by jugular puncture, periorbital puncture or tail vein puncture, or sampled by jugular puncture in carbon dioxide (CO2), isoflurane or without anaesthesia in a crossover design. Heart rate, blood pressure and body temperature were registered for three days after sampling. Initially blood pressure increased, but shortly after sampling it decreased, which led to increased heart rate. Sampling induced rapid fluctuations in body temperature, and an increase in body temperature. Generally, rats recovered from sampling within 2-3 h, except for rats sampled from the tail vein, which showed fluctuations in body temperature in excess of 30 h after sampling. Increases in heart rate and blood pressure within the first hours after sampling indicated that periorbital puncture was the method that had the largest acute impact on the rats and that it might take an extra hour to recover from it. CO2 anaesthesia seemed unable to prevent the increase in blood pressure and the fluctuations in body temperature induced by blood sampling, and up to 10 h after sampling, the rats were still affected by CO2 anaesthesia. Rats anaesthetized with isoflurane showed lower increases in blood pressure after, and fewer fluctuations in body temperature during sampling, and the post-anaesthetic effects of isoflurane, if any, seemed to disappear immediately after sampling. It is, therefore, concluded that blood sampling in rats by jugular puncture seems to be the method from which rats most rapidly recover when compared with periorbital puncture and tail vein puncture, and that for anaesthesia, isoflurane is recommended in preference to CO2.

Ketamine-xylazine-acepromazine anesthesia and postoperative recovery in rats

We evaluated the effect of ketamine-xylazine-acepromazine anesthesia (31.25, 6.25, and 1.25 mg/kg subcutaneously, respectively) on postsurgical recovery in male Sprague-Dawley (Crl:SD) rats undergoing laparotomy with and without the postoperative analgesic ketorolac. Recovery was determined by changes in body weight (BW) and water intake. The time of ketorolac administration (5 mg/kg intramuscularly), 60 min after anesthetic injection, was based on return of the pedal withdrawal reflex in Long-Evans (HsdBlu:LE) rats undergoing stereotaxic surgery in a separate experiment. Results were compared with those of housing and anesthesia controls as well as of laparotomized rats receiving a single sugared treat for nonpharmacologic management of postoperative pain. Surgery took place on day 0; the first 24 h postsurgery was considered the "acute phase," and days 1 through 4 comprised the "recovery phase." Results suggest that 1) the anesthetic mixture is fast- and long-acting and provides sufficient immobility, loss of consciousness, and analgesia; 2) during the acute phase, rats subjected to laparotomy did not lose more BW than rats exposed to anesthesia alone; 3) water intake during both phases did not significantly differ between treatment groups; 4) postsurgical ketorolac administration did not minimize BW loss during the acute phase nor cause any adverse effects under this anesthetic regimen; and 5) provision of single sugared treats had salutary effects on BW recovery. This finding suggests that postsurgical BW loss after use of this anesthetic mixture is due to distress unrelated to pain; this nonpain distress may have masked potential beneficial effects of ketorolac.

Transfusion via the carotid artery in the hamster

Public health policy makers need quantitative scientific data to assess the risk to the blood supply posed by transmissible spongiform encephalopathy (TSE) diseases. To this end, our laboratory has developed a model of blood-borne TSE infectivity in hamsters infected with the 263K strain of scrapie, an experimental model of choice for quantitative studies of TSE infectivity. We report here a microsurgical method for cannulation of the carotid artery in the hamster that allows transfusion of a large fraction of the blood volume of the hamster, with virtually no blood loss to the surgical site or exposure to nervous tissue. Animals are minimally affected by the surgery, recover quickly and completely, and survive for their natural lives (as long as 3 years). This procedure has been used to obtain quantitative data on the transmissibility of the TSEs by transfusion, and these findings have informed public health policy on blood donation and blood use.

Thyroparathyroidectomy procedures and thyroxine levels in the chinchilla

Thyroid and embedded parathyroid glands were surgically removed (thyroparathyroidectomized) from adult chinchillas (Chinchilla laniger) to create an animal model of hypothyroidism. Thyroxine (T4) levels were measured at the time of surgery and one or two times after surgery from 10 thyroparathyroidectomized chinchillas and five sham controls to establish baseline serum T4 levels and to assess the degree and duration of hypothyroidism in this animal model. Baseline T4 levels ranged from 3.4 to 6.4 microg/dl (mean +/- 1 standard deviation, 5.25 +/- 0.84 microg/dl), with no differences between male and female chinchillas (5.4 +/- 0.6 microg/dl versus 5.2 +/- 1.0 microg/dl, respectively). T4 levels were significantly reduced in 80% of thyroparathyroidectomized chinchillas when measured 6 to 14 days after surgery, but reductions were variable, ranging from 9 to 89% in individual animals. There was rapid regrowth of thyroid tissue and a return of T4 levels to the baseline range in five of the seven animals followed for 1 to 2 months after surgery. T4 levels increased significantly in the sham-operated chinchillas, indicating a nonspecific effect of surgery. The results establish surgical procedures for creating a model of variable, transient hypothyroidism in the chinchilla. We also summarize published basal T4 values for various laboratory animals, to provide a convenient reference.

A study of VitalView for behavioural and physiological monitoring in laboratory rats

We describe the use of a commercially available telemetry and data acquisition system to record heart rate, body temperature and activity of freely behaving rats with transmitters that operate without batteries (transponders). The system uses PDT 4000HR E-Mitters (Mini Mitter, OR, USA) to acquire animal temperature, heart rate and motor activity data. E-Mitters obtain power from a radiofrequency field produced by an ER-4000 energizer/receiver so that transponders can collect data on heart rate, body temperature and gross motor activity. ER-4000 energizers/receivers are designed to be placed below the animals' cage. Data output from receivers is managed by a Windows PC-based data acquisition system, VitalView. In this study, we report that a good correlation exists between VitalView and Powerlab for the determination of heart rate and between intra-abdominal (telemetric) and colonic body temperature (rectal digital thermometer) in rats. Assessment of this system by using agents that have well-documented effects on heart rate, body temperature and locomotor activity have also been determined. An additional feature of VitalView is the incorporation of behavioural inputs (feeding monitors to monitor duration and frequency of feeding and a lickometer to monitor drinking bouts) into the data acquisition system designed primarily to acquire data from the implanted transponders. Circadian rhythms for all parameters were established in rats with E-Mitters implanted. VitalView may be used for the determination of multiple parameters in freely behaving animals using transponders, which operate without batteries. This capability is unique in its field and represents a recent advance in biotelemetric monitoring of laboratory animals.

Anesthesia update: agents, definitions, and strategies

The trend in modern anesthesia is to "lighten up." This generally involves use of several drugs with selective and complementary actions. The pharmacokinetic properties of such drugs should allow rapid onset, rapid recovery, and rapid responses to changes in delivered doses. Peri-operative management issues also are inherent to use of modern drugs and techniques. For example, provisions must be in place for postoperative analgesia if rapid recovery is anticipated. Light anesthesia reduces morbidity and mortality, and reduces the drug, facility, and personnel costs associated with anesthesia. However, the requirements for anesthesia and the expertise of personnel administering anesthesia vary considerably. Many regulatory bodies and scientific journals require a description of how anesthesia adequacy and depth will be assessed, as well as extensive justification for the use of neuromuscular blocking agents. In environments where adequate experience and sophistication for the use of cutting edge drugs and methods are not available, older drugs and techniques may be adequate and preferable to protect animals from pain or distress.

Introduction to microsurgery: an emerging discipline in biomedical research

Using microsurgical techniques, biomedical researchers are able to perform procedures that would otherwise be impossible on small laboratory animals. The authors provide a primer on learning microsurgical technique, from correct posture and hand position, to understanding lenses and proper handling of surgical needles and suture material.

[Experimental models for testing new surgical methods and materials]

The main models of operative interventions, used for examination of new surgical suturing and nonsuturing methods of the tissues connection are presented; the animals applied in such a purpose, the anesthesia support schemes for every kind of laboratory animals were noted.

Collection of pancreatic juice in experimental animals: mini-review of materials and methods

This article briefly describes some anatomical details of the pancreatic duct system in dogs, cats, cattle, sheep, goats, pigs and rats that are important for the preparation of pancreatic ducts for surgery. The advantages and disadvantages of various materials used for preparing cannulas and catheters for the collection of pancreatic juice are also presented. Several techniques of pancreatic duct cannulation (Thomas', duodenal pouch and Routley's methods) and pancreatic juice collection are discussed with regards to the specificity of different animal species. The results of various collections of pancreatic juice obtained in different laboratories, and resulting from the application of specific methods for particular experimental purposes are discussed.

Tracheoesophageal anastomosis, continent gastrostomy and oesophagostomy--a new experimental model in minipiglets

Tracheoesophageal fistulae endanger newborn children by aspiration pneumonia. An animal model of this dangerous malformation was thought to be impossible until now. By tracheoesophageal anastomosis, occlusion of the oesophagogastral junction, proximal cervical oesophagostomy and continent gastrostomy in 25 minipiglets a reliable model of tracheoesophageal fistula has been developed. After establishing the model in a pilot study the mortality following the establishment of this procedure was 5.6% and the minipiglets survived in excellent condition for 2-10 week periods under complete alimentary restriction and gastrostomy feeding. Therefore the method seems to be suitable for long-term investigations on major oesophagotracheal surgery.

An improved technique for visually controlled pinealectomy in the rat

An improved method for pinealectomizing rats and other small laboratory rodents is described which avoids bleeding and allows excision of the organ under exact visual control. After removing a small piece of the skull dorsal to the confluence of the transverse and dorsal sagittal sinuses, the latter is ligated and cut. The underlying pineal gland is then exposed and may be excised reliably without damage to the gland tissue or to adjacent brain structures. Intra- and post-operative complications are extremely rare.

Blood collection and surgical procedures for the laboratory opossum (Monodelphis domestica)

Procedures have been developed for collecting blood samples from the laboratory opossum (Monodelphis domestica) and for conducting survival surgery on adults. Blood samples up to 1 ml were collected routinely by cardiac puncture of animals anesthetized by inhalation of methoxyflurane or halothane with minimal risk; however, halothane required more careful monitoring. Surgical procedures such as partial hepatectomy unilateral hysterectomy, and tail wound repair were safely accomplished on animals anesthetized with methoxyflurane. Other surgical procedures including enucleation and intra-abdominal vasectomy were carried out successfully with an inhalation/injection (pentobarbital-atropine-ketamine) protocol that was successful also for recipient surrogate females in embryo transfer experiments.

Guidelines for animal surgery in research and teaching. AVMA Panel on Animal Surgery in Research and Teaching, and the ASLAP (American Society of Laboratory Animal Practitioners)

The direct or delegated authority for activities involving animals used in research and teaching programs lies with the attending veterinarian. These duties and responsibilities cannot be abrogated by others in the organization. The veterinarian is the single individual with the broadest range of knowledge of animals used in biomedical research, testing, and teaching. Federal regulations and policy require that the Institutional Animal Care and Use Committee (IA-CUC) ensure that the use of animals will be ethically justifiable and humane and that all individuals who perform surgery on animals will be appropriately qualified and trained. The attending veterinarian also has specific responsibilities under law and must take an active role in providing this assurance. In recognition of this, the Council on Research of the AVMA created a Panel on Animal Surgery in Research and Teaching to develop a report on guidelines for performing animal surgery in a research or teaching setting. Drafts of the panel report were sent through an extensive review process that included representative groups in veterinary medicine, human health, government, biomedical research, and animal welfare. The report of the panel was referred to the American Society of Laboratory Animal Practitioners (ASLAP). As an organization, the major focus of which is the role of the veterinarian in research using animals, it is appropriate that the ASLAP further refine this report into a set of guidelines for the research community. The ASLAP committee wishes to acknowledge the AVMA for recognizing the need for these guidelines and providing the financial support to convene the initial panel. This document was compiled with expectations for change in future revisions. Intended to complement other pertinent guidelines and regulations on animal surgery, these guidelines are designed to help individuals charged with the stewardship of animals used in research and teaching.

Technique for in situ excision of distended samples of greater omentum from small laboratory animals

A simple and reliable technique is described for in situ excision of distended samples of greater omentum from small laboratory animals. The omental bursa is distended by injecting whipped hen egg white. Filter paper frames then are applied to the selected areas of distended omentum and samples of omental membrane are excised together with the filter paper frames. This sampling technique yields undamaged materials suitable for various research purposes.

[The first experience with the concurrent effect of YAG-neodymium and YAG-erbium laser on experimental animal tissues and the possibility of its use in surgery]

To guarantee the necessary rate of cutting live tissues with adequate hemostasis along the line of the incision, the authors studied isolated and joint effect of radiations of AIG-neodymium and AIG-erbium lasers on the tissues of laboratory animals. The possibility of accomplishing intraoperative hemostasis on the parenchymal organs was studied in experiments with AIG-neodymium laser. A good dissection effect in cutting various tissues was produced in the second series of experiments with AIG-erbium laser. The simultaneous action of AIG-neodymium and AIG-erbium beams converged at one point on the surface of the biological object was studied in the third series of experiments. It was found that the effect ensures a good dissection of tissues with sufficient hemostasis. The results of dynamic morphological studies are shown. The possibility of using the device in surgery is discussed.

Guidelines for training in surgical research in animals, Academy of Surgical Research, April 1989

This document is not meant to be a regulatory statement but rather to be utilized as a guideline for research institutions who are trying to adhere to the training regulations detailed by various governmental agencies. It is our hope that institutions and individuals will take a proactive stance in requiring adequate training and experience for persons performing experimental surgery on laboratory animals. Only by adherence to voluntary standards that ensure humane care and use of laboratory animals in research can we expect to avoid more stringent laws and regulations. More importantly, by adhering to these voluntary standards the quality of animal research can be improved, which should result in more effective and efficient use of our resources.

Anesthesia and surgery of laboratory animals

This article reviews anesthetics and anesthetic techniques applicable to small laboratory animals. Anesthetic and analgesic dosage tables are presented for each species to guide the practitioner. The actions of the various agents are reviewed in the text, and key references are presented. Surgical considerations are also reviewed.

Isoflurane as an anesthetic for experimental animal surgery

Isoflurane is an inhalational anesthetic agent associated with no known hepatic toxicity. Despite this fact, isoflurane has not been widely utilized as an anesthetic agent in studies of liver structure and function in experimental animals. For this reason, livers from rats treated with pentobarbital or diethylether were compared to those from rats treated with isoflurane to determine differences in biochemical and morphologic parameters. Liver from pentobarbital-treated rats showed a significant decline in glutathione-S-transferase activity compared to liver from isoflurane/O2 or ether-treated rats. Liver microsomes from isoflurane/O2-treated rats retained more cytochrome-C(P450)-reductase activity than did those from pentobarbital-treated, ether-treated, or decapitated rats. Despite these biochemical alterations, morphometric analysis of liver from isoflurane/O2 and pentobarbital-treated rats showed no quantitative or qualitative differences in liver structure or organelle volume densities. Neither were differences detected in uptake and distribution of 125I-epidermal growth factor when analyzed by electron microscopic autoradiography. These data show that isoflurane with supplemental O2 has no effects on hepatic structure and fewer effects on hepatic function than other anesthetics and may be a better experimental anesthetic than any currently in use.

Microsurgery in the clinic and laboratory

Laboratory animals have been crucial to the development of modern microsurgical techniques which are now routinely used in many clinical departments worldwide. In return, microsurgical techniques are important in biomedical research as they allow many surgical procedures to be performed on rodents instead of dogs, pigs or primates. This has obvious advantages in terms of low cost, the use statistically valid numbers for comparison and the availability of genetically defined animals which are more likely to give valid answers to immunological questions. Microsurgical reconstruction is important in plastic, orthopaedic, urogenital, vascular and peripheral nerve surgery in man and it is likely that it will become part of every surgeon's training in the near future. In this review, the instrumentation essential to any microsurgical enterprise and the sutures available are described. Basic microsurgical techniques for end-to-end and end-to-side anastomosis of small vessels and for joining peripheral nerves, oviducts and other tubular structures are given in outline. Techniques for transplanting kidney, heart, heart and lung, liver, spleen, pancreas, small bowel, stomach, testicle, ovary and whole joint are only outlined but key references are given. Finally, some of the clinical indications for microsurgical reconstruction are reviewed.

Swine as replacements for dogs in the surgical teaching and research laboratory

Commercially produced swine were successfully used to replace dogs in several surgical research projects at The Johns Hopkins University School of Medicine. They were especially successful as replacements for dogs in the basic operative surgery course offered as an elective to medical students. Advantages of swine over dogs included anatomic and physiologic characteristics shared with man, better health, and economic considerations.

A closed anesthetic system for small laboratory animals

An anesthetic unit was developed that maintained adequate anesthetic levels, removed carbon dioxide, and contained gases. The device produced inhalation anesthesia in both small mammals and birds by using either halothane or methoxyflurane.

Imperforate vagina in mice: per cent incidence and surgical repair

An inbred strain maintained at Nagoya University, Laboratory of Animal Genetics, produced high incidence of imperforate vagina as 12.21% of occurrence in females, herein designated as Imv strain. Selected females with imperforate vagina in this strain were surgically repaired and subsequently mated with their littermates. These matings produced a 12.76% incidence of imperforate vagina. A detailed description of the surgical technique is herein reported.

Small intestinal anastomosis and preparation of intestinal loops in the rabbit

An end-to-end anastomotic technique was adopted to prepare isolated intestinal loops in rabbits. The anastomosis was accomplished by the use of a simple interrupted approximating suture technique which caused minimum trauma to the intestinal tissue, and the luminal narrowing was minimal. Normal intestinal functions were resumed in less than 48 hours. The operated rabbits maintained normal appetite, normal passage of digesta, and normal weight gains. The advantage of this method was the ability to operate rapidly and certainty of effect.

Exteriorization of the bile duct in germfree rats

A modified T cannula and a cannula housing receptacle was employed to cannulate the bile duct of germfree rats. Bile was collected without anesthesia or sedation. During collection, the rat was restrained in a plastic holder where it was free to eat.