Kazuaki W. Takahashi

Fine structure of three types of olfactory organs in Xenopus laevis

There is no report on the fine structure of three types of olfactory organs in Xenopus laevis. Their functional assignments in olfaction are not yet established. The fine structure of three types of olfactory organs, olfactory epithelium (OE), vomeronasal organ (VNO), and middle chamber epithelium (MCE), was examined in Xenopus laevis by light and electron microscopy. The olfactory cells of the OE and the sensory cells of the VNO were equipped with cilia and microvilli, respectively, similar to terrestrial animals that possess both the OE and the VNO. On the other hand, the sensory cells of the MCE were classified into two types, the sensory cells with cilia and the sensory cells with microvilli, like those of the OE in fish. These findings suggest that the OE and the VNO in Xenopus laevis detect different kinds of odoriferous molecules in air, whereas the MCE is involved in the perception of odorants in water. Anat. Rec. 252:301–310, 1998.

A simple method for intravenous injection and blood collection in the chinchilla (Chinchilla laniger)

A simple method is outlined for intravenous injection and blood collection from a peripheral vein in the chinchilla. Seven peripheral vein sites were successfully venipunctured in unanaesthetized chinchillas: the femoral, cephalic, auricular, saphenous, dorsalis penis, lateral abdominal and tail veins. The femoral and cephalic veins were found to be the best sites for injection and blood collection.

A simple method for prevention of coprophagy in the mouse

A series of studies of coprophagy in mice has been conducted from the viewpoints of behaviour and nutrition. Since it was necessary to prevent coprophagy to investigate its significance, an attempt was made to devise a re-strainer. A polyethylene bottle was cut and fixed to the mouse so as to prevent its head from reaching its anus when faeces were excreted. The animals were also housed in cages with floors of larger mesh size in order to let the faeces fall through.

Para-chloroamphetamine (PCA)-induced ejaculation in aged rats, semen analysis and artificial insemination

The present study was undertaken to determine sperm motility and counts in semen yielded by para-chloroamphetamine (PCA)-induced ejaculation of aged rats which had lost their reproductive ability, and to attempt artificial insemination with suspensions of spermatozoa obtained in this way. The semen yielded by PCA-induced ejaculation from aged (75-week-old) rats had average sperm counts of 0.82±0.69 × 107, which were much lower than the average counts (9.42±1.65 × 107) for semen spontaneously ejaculated by young adult rats (14 weeks old). However, 77.5% of the spermatozoa contained in the PCA-induced semen were rated as showing the most active movement. Spermatozoa collected in this way were injected into the upper parts of both uterine horns or into both ovarian bursae. Both methods made the females pregnant, but the results were better after injection into the ovarian bursae. The offspring born to these females showed no abnormalities.

Structural Outline of Spontaneous Motor Activity Monitor Using Infrared Photoelectric Switch for Small Animals

: A simple monitor was developed for measuring the spontaneous motor activity (SMA) of small laboratory animals. The monitor was designed to measure animal ambulation along a horizontal axis by means of two infrared photo-beams. Using the monitor, male mice 7 to weeks of age at the commencement of this experiemtn showed high SMA values for the first 15 min and low values for the last 15 min of the experiment.

The Application of Industrial Endoscope to Observation of the Ocular-fundus in Small Laboratory Animals

Observation and recording methods of the ocular-fundus in small laboratory animals were studied using the industrial endoscope and VTR systems, respectively. The ocular-fundus was observed widely, brightly and clearly in the usual animal facility. In addition, the ocular-fundus was recorded easily and it was possible to examine the ocular-fundus recorded by the VTR systems.

Effects of pup exposure to maternal nest building in virgin female and male mice

Nest-building behavior in 6 female and 6 male mice of IVCS strain, 20 to 30 weeks old, was studied over a period of 24 days. Weight and style of the nest were used as measures to assess the effects of pup exposure on nest-building. Data were collected between 13 : 00 and 14 : 00 of each day. Female mice with pup exposure showed significant increases in the nest weight and the percentage of good-excellent nest, while males did not respond.