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Historical control data on rabbit prenatal developmental toxicity studies, performed between 1994-2010, were obtained from 20 laboratories, including 11 pharmaceutical and chemical companies and nine contract laboratories, in Japan. In this paper, data were incorporated from a laboratory if the information was based on 10 studies or more. Japanese White rabbits and New Zealand White rabbits were used for prenatal developmental toxicity studies. The data included maternal reproductive findings at terminal cesarean sections and fetal findings including spontaneous incidences of morphological alterations. No noticeable differences between strains or laboratories were observed in the maternal reproductive and fetal developmental data. The inter-laboratory variations in the incidences of fetal external, visceral, and skeletal alterations seem to be due to differences in the selection of observation parameters, observation criteria, and classification of the findings, and terminology of fetal alterations.

Historical control data from prenatal developmental toxicity studies in rats have been used to evaluate whether toxicology outcomes were induced by exposure to a chemical or were within the range of spontaneous variation. These data are also important for monitoring animal characteristics. As a follow-up to historical control data from 1998 to 2010, this study analyzed control data from prenatal developmental studies performed in rats from 2011 to 2015. Data were collected from studies performed by 24 Japanese laboratories, including 15 pharmaceutical and chemical companies and nine contract research organizations, in Sprague-Dawley and two-sub-strains of Wistar Hannover rats. The data included maternal reproductive findings at terminal cesarean section and fetal findings, including incidences of spontaneous external, visceral, and skeletal anomalies. No noticeable differences in maternal reproductive data were observed among laboratories. The inter-laboratory variations in the incidences of fetal anomalies seemed to be due to differences in the selection of observation parameters, observation criteria, and classification of the findings, as well as to differences in terminology of fetal alterations. These historical control data may be helpful for adequate interpretation of experimental results and for evaluating the reproductive and developmental toxicities of various chemicals.

A comparison among rat sperm motility test methods including percent of motile sperm (% Motile), scoring method (Scoring), Ishii's method, Progressive Motility Test (PMT) and Sperm Quality Analyzer (SQA), was conducted using data gathered from eleven laboratories. As a unified study design, mature male rats were orally treated daily for approximately 1 week with alpha-chlorohydrin (ACH), which is known to affect the sperm motility at the epididymis, at dose levels of 2.5, 5 and 10 mg/kg, and then subjected to more than two test methods for sperm motility in each laboratory. Scoring (4 or 5 grades), Ishii's method, PMT and SQA showed high sensitivity for the detection of the effects of ACH, which were not considered to be inferior to a computer-assisted sperm analyzer (CASA). Longer incubation time before testing was considered to contribute to detecting the effects of ACH. In particular, we realized that Scoring was a favorable method even if the demerit of poor objectivity was allowed for. Percent Motile showed lower sensitivity than other test methods. The differences in sensitivity between % Motile and other methods were considered to be based on whether the defects of progressive motion could be detected. Although % Motile cannot clearly judge whether immotile sperm are dead or alive, the value is a great help for the interpretation of the result from other methods. Based on the characters for detectability, objectivity and efficiency, the most suitable method of sperm motility should be selected according to the purpose of the toxicity study.