Oral infectivity of street and fixed rabies virus strains in laboratory animals

Oral transmission of rabies could be produced in laboratory animals like mice, guinea pigs and hamsters using challenge virus strain (CVS) and 2 strains of street virus. Study of virus pathway following ingestion suggested predominant neural spread to brain and centrifugal spread to non neural organs like heart and kidneys. However it was found that virus dose required for oral infection was relatively very high. The role of such a transmission in nature needs to be further evaluated, keeping in view the high dose of virus required for oral infectivity and the frequency of consumption of brain by carnivorous animals.     

No differences in pineal synaptic ribbon and spherule numbers in different stocks and strains of laboratory rats

Previous studies have shown that the pineal glands of different stocks and strains of laboratory rats have different melatonin-forming capacities. In the present investigation a widely studied morphological parameter of the pineal, i.e. synaptic ribbon (SR) and synaptic spherule (SS) numbers, was explored in 6 different stocks and strains of laboratory rats, viz.:Han:WIST (albino), LEW/Han (albino), DA/Han (agouti), BN/Han (dark brown), LE/Han (black hooded) and (LEW x BN)/F1 (black with white belly). The rats were maintained under the usual laboratory conditions (lights on from 06.00-18.00 h) for 3 weeks and killed between 10.00-12.00 h, when they were 6 weeks old. The pineals were rapidly excised and processed for transmission electron microscopy. The morphology, distribution (in singles or groups, distant from, or near cell membrane etc.) and number of SR and SS per 20,000 microns2 area of pineal tissue were similar in all groups of rats studied. It is concluded that, in contrast to pineal gland size and melatonin synthesis, SR number is a fairly constant pineal parameter in different stocks and strains of laboratory rats and independent of pigmentation.     

实验动物的质量管理与控制

我国通过建立的实验动物法律法规、管理制度、技术标准、许可证制度、动物质量检测体系等一系列措施,加大了对实验动物的管理力度。目的是提高和保证实验动物质量,提高实验动物科技水平和生命科学研究水平。同时,随着管理力度的加大和人们认识水平的提高及动物环境设施的改善,动物的福利也得到了很大的改善和提高,更有利于提高动物试验结果的准确性和可信性。     

Spirograph for small laboratory animals

A design of dry spirograph is described. It is characterized by greater precision, lack of inertia, high reliability, absence of respiration resistance, adequate form of recording, rapid resetting to any respiratory rate. The device consists of two similar injection syringes, photoelectric sensor for the identification of the initial moments of respiration stages, electromagnetic valves, two photoelectric converters of the air volume into the impulse signal, vacuum micro-pump, microcompressor and a system of air-driving tubes. In the initial position of pistons and valves the microcompressor pumps air into the inhalation cylinder and lifts the piston to the upper extreme position. With the signal marking the beginning of inspiration, the valves switch over and the piston lowers, pushing out the air, which moves into the animals' respiratory organs. Simultaneously, the signals of the inhaled air volume from the photoelectric transducer reach the recorder. During expiration the air pushes the piston down into the second cylinder and photoelectric transducer gives the information on the volume of the expired air.     

Adoption options for laboratory animals

Adoption programs can be enormously satisfying for all involved-not least the animals themselves-and constitute an important refinement in humane animal care and use. Most of the potential problems associated with adoption can be minimized with careful thought and planning. The authors describe adoption programs at two large academic campuses, noting differences between direct and indirect programs.     

New microinsemination techniques for laboratory animals

Since the development of a reliable mouse intracytoplasmic sperm injection (ICSI) technique in 1995, microinsemination techniques have been widely applied in several laboratory species. As gametes and embryos have specific biological and biochemical features according to the species, technical improvements are necessary for successful microinsemination that subsequently leads to normal fetal development in several species. Recent advanced reproductive research involving genetic engineering often depends on microinsemination techniques that require a high degree of skill, and new human assisted reproductive technology (ART) requires experimental models using laboratory animals. The accumulation of technical improvements in these fields should accelerate the development of microinsemination techniques in mammals, including humans.