Developmental toxicity of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). II. Multireplicated dose-response studies with technical and analytical grades of 2,4,5-T in four-way outcross mice.

A series of multireplicated developmental toxicity studies were conducted in four-way outcross mice and CD-1 outbred mice administered either analytical or technical grades of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) by gavage on Gestational Days 6 through 14. The formulations of 2,4,5-T differed by a factor of 10-fold in 2,3,7,8-tetrachlorodibenzo-p-dioxin levels. Reduced fetal weight and increased incidences of cleft palate and embryolethality were the most significant prenatal effects of both formulations of 2,4,5-T observed in all strains/stocks of mice. Both the outcross and outbred mice exhibited a dose-response relationship with each of the above endpoints and the dose-response curves were parallel. There were no embryotoxic or fetotoxic differences between the technical and analytical grades of 2,4,5-T with regard to extent of fetal weight reduction, resorption rate, or cleft palate incidence. There was little difference in the results between the four-way outcross mouse and the CD-1 outbred mouse.

Breeding, allocation and maintenance of mice for a large, long-term carcinogenic study (ED01 study).

The breeding, allocation and maintenance data on BALB/c female mice in a 24, 192 mouse chronic carcinogen feeding study are discussed. In establishing the breeding colony, standard derivation techniques were used to develop a barrier-maintained production capability. Genetic histories and other breeding colony records were maintained with the assistance of a computer-supported Breeding Information System. A computer-supported allocation system provided the link between the breeding and experimental portion of the study. Once allocated to the experiment, the mice were weighed and observed weekly; feed consumption data was also collected. All animal and cage information was entered directly into the computer data base via special terminals and electronic balance units. From this experiment's data base, daily and weekly reports were generated which provided valuable information for the operational and scientific management of the experiment.

Computer record keeping in a large rodent colony.

An automated information system was developed to aid in the record keeping of inbred rodent breeding colonies. The system had keyboard terminals in each breeding room linked to a local mini-computer for data collection, editing, and short-term storage; and a remote, large computer center for permanent storage and report generation. The system allowed an animal technician to record all the activities associated with an inbred rodent breeding colony such as recording births of litters, weanings, assignment of animals, disposition of animals, and health observations. The information collected was available in daily reports provided within 24 hours after observations were recorded; weekly compilations that summarized the daily events; and special reports such as pedigrees, which were available on request.