A Critical Assessment of the Requirement for a Single Time Point Vaginal Cytology on the Day of Necropsy in Rats.

For toxicology testing of (agro)chemicals, different study types are being performed with general and/or reproductive toxicity endpoints (see Organisation for Economic Co-operation and Development guidelines). In most of these rat studies, vaginal cytology is performed on serial samples (collected by lavage) for evaluation of cycle regularity and evidence of mating, and/or on a single sample collected on the day of necropsy for information on the estrous cycle stage and allowing correlation with histopathology. In the latter case, the utility of vaginal cytology can be argued.

Satellite rats are redundant in embryo-fetal development studies.

Routinely in many laboratories, satellite rats are added to embryo-fetal development (EFD) studies for pharmaceuticals to assess toxicokinetic (TK) properties, because it is assumed that collection of multiple blood samples with relatively large volumes might affect the study outcome. With recent refinement of blood sampling techniques, this belief requires reevaluation. The current work showed successful implementation of jugular vein blood sampling in an EFD rat study without satellite animals, thereby reducing the number of rats in standard EFD studies for pharmaceuticals by 20%.

Estrous cycle-dependent morphology in the reproductive organs of the female Göttingen minipig.

The present study describes the normal histology of female reproductive organs during the estrous cycle in the Göttingen minipig. For this purpose, sexually mature females were sacrificed at different phases of the cycle (follicular/proliferation, ovulation, and early-, mid-, and late-luteal/secretory phase). Ovaries, uterus, cervix, vagina, and mammary gland tissues were processed for microscopic evaluation.