The authors report no conflict of interest. Data S1. Supporting information. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Outsourcing of preclinical developmental and reproductive toxicology testing (DART) is accelerating, but the availability of experienced, well-qualified individuals responsible for DART is diminishing. Current DART training at all levels is anemic. We identify four requisite training areas including hands-on technical skills, scientific knowledge, management, and oral/written communications. We suggest that comprehensive training could be accomplished through DART-targeted certificate programs or post-baccalaureate curricula designed and funded by the combined efforts of industry consortia, contract research organizations, government, and academia. Graduates of such training would be better able to serve as DART technicians, study directors, study monitors or regulatory scientists.

INTRODUCTION:Quaternary ammonium compounds (QUATs) are commonly found in cleaning products, disinfectants, hand sanitizers, and personal care products. They have been used for >50 years and are considered safe when used according to directions. Recent papers report reduced fertility and neural tube defects in rodents after low-level exposures. To determine if QUATs interfere with mammalian reproduction and development, we conducted a methodical assessment of all available data.METHODS:A systematic literature search identified 789 potential articles. Review of titles and abstracts found eight relevant studies, including two dissertation chapters; to these, 10 unpublished, guideline-compliant developmental and reproductive toxicity (DART) studies of QUATs (alkyldimethylbenzylammonium chloride [ADBAC] and dialkyldimethylammonium chloride [DDAC]) were added. ToxRTool was utilized to evaluate all 18 studies for data quality.RESULTS:Six studies were scored as "reliable without restriction"; four studies were considered "reliable with restriction" (mainly due to small rabbit group sizes). No test article-related, adverse DART endpoints were reported in these studies. ToxRTool scored the remaining eight studies as "not reliable." The unreliable studies failed to fully describe methods and/or endpoints, did not quantify (and in some cases, did not verify) exposures, utilized non-standard test methods, reported endpoints incorrectly, and assessed endpoints at inappropriate times. Some (not all) unreliable studies reported adverse effects after 7.5 mg QUATs/kg/day (mice), but these results were inconsistent. The reliable studies tested exposures ≥100 mg/kg/day (rats) with no effects.CONCLUSIONS:The available weight of evidence indicates no adverse DART effects after QUATs exposures at anticipated concentrations and normal use.

In 2016 one person died and others had neurological sequelae during a clinical trial with BIA 10-2474 (3-(1-(cyclohexyl(methyl)carbamoyl)-lH-imidazol-4-yl)pyridine 1-oxide), a novel fatty acid amide hydrolase (FAAH) inhibitor being developed for the treatment of medical conditions such as pain. Prior to the clinical trial a full battery of regulatory toxicology tests were carried out and this paper describes the genotoxicity/mutagenicity tests undertaken with BIA 10-2474 using the Ames (Salmonella typhimurium) reverse mutation test, the Escherichia coli WP2uvrA forward mutation test, an in vitro chromosome damage assay in human lymphocytes, and an in vivo micronucleus test in mice. All tests were conducted with and without a rat liver S9 metabolic activation system. None of the test results were judged to be positive with regards to the mutagenicity/genotoxicity of BIA 10-2474 making it unlikely that any such effect was involved in the toxicity observed in the clinic.

BIA 10-2474 (3-(1-(cyclohexyl(methyl)carbamoyl)-1H-imidazol-4-yl)pyridine 1-oxide) is a novel fatty acid amide hydrolase (FAAH) inhibitor developed by BIAL for the treatment of medical conditions which would benefit from enhanced levels of endogenous anandamide (AEA) such as pain disorders. During a Phase I clinical trial one subject died after receiving BIA 10-2474 and others displayed neurological signs. As part of series of papers presenting all the toxicology data available prior to the clinical trial we report here the nonclinical toxicology studies performed in cynomolgus monkeys. Maximum Tolerated Dose (MTD) studies and a preliminary 14-day study by oral (capsule) administration of BIA 10-2474 established a dose between 90 and 120 mg/kg/day as a suitable high dose for a subsequent regulatory toxicity studies. An up-titration scheme was used to achieve these doses. The dose-limiting effect was the early sacrifice for ethical reasons of monkeys at doses from 125 mg/kg/day upwards. Thereafter, regulatory 4- and 13-week oral gavage toxicity studies followed by a 2- or a 4-week recovery period, respectively, were performed. In both cases a 3-4-week up-titration period was used prior to repeat dosing with the target doses. One female was euthanized during the up-titration period after receiving 9 administrations of 75 mg/kg as a result of bleeding erosion on the feet and hands and ulceration on the tongue. These signs were not seen in any other monkeys during these studies. Doses of 10, 50 or 100 mg/kg/day were administered during the 4-week study and clinical signs related to the pharmacological action of BIA 10-2474 (e.g., tremors and weakness, incoordination and loss of balance, reduction in food intake and reduced body weight) were observed in several monkeys from the intermediate and high dose. Histological alterations consisted of axonal dystrophy in the fasciculus cuneatus (dorsal medulla oblongata) characterized by swollen axons and myelin sheath edema, edema in the pars nervosa of the pituitary gland and vacuolation of Meissner's plexus ganglia in all gastrointestinal segments. All lesions recovered and a dose of 100 mg/kg/day was considered to be the NOAEL. In the 13-week oral study the monkeys received BIA 10-2474 daily by gavage at a dose of 6.25, 37.5 or 75 mg/kg/day. Similar clinical signs and histological alterations as noted in monkeys of the 28-day study were observed in monkeys at 37.5 or 75 mg/kg/day. All findings recovered, and the dose of 75 mg/kg/day was considered the NOAEL.

BIA 10-2474 is a novel fatty acid amide hydrolase (FAAH) inhibitor developed for the treatment of medical conditions which would benefit from enhanced levels of endogenous anandamide (AEA) such as pain disorders. During a Phase I clinical trial one subject died after receiving BIA 10-2474 and four other subjects displayed neurological signs. As part of series of papers presenting all the toxicology data available prior to the clinical trial, we report here the preclinical toxicology studies examining once-a-day oral administration of BIA 10-2474 to male and female Wistar rats. These included a 14-day dose range finding (150, 200 and 250 mg/kg/day), a 4-week study (30, 90 and 150 mg/kg/day) and 13- and 26-week studies (both at 10, 30 and 90 mg/kg/day). The 13- and 26-week studies also included a 4-week recovery arm and a toxicokinetic arm for the parent compound, BIA 10-2474, and the two major metabolites (BIA 10-2445 and BIA 10-2583) were also measured in the 26-week study. At 150 mg/kg and below, all animals survived the scheduled treatment periods although neurological side-effects (abnormal or stiff gait, dragging of fore- or hind-limbs) were seen at 150 mg/kg in both the dose-range finding and 4-week studies. At 90 mg/kg/day, even up to 26-weeks treatment, no clinical signs were seen apart from some decreases in body weight gain. A number of consistent hematological and biochemical changes were noted which were considered related to treatment with BIA 10-2474. Morphologically, in the 4-week study, except for a slight gliosis in the hippocampus of one female at 150 mg/kg, no CNS histopathology was observed; hippocampus gliosis was not observed in subsequent studies. In the 13-week study axonal swelling was present in the medulla oblongata in about half the animals at 90 mg/kg/day and this increased to nearly all the rats at 90 mg/kg/day in the 26-week study. Additional signs seen only in the 26-week study at 90 mg/kg/day included axonal swelling of the fasiculus gracilis and vacuolar changes in the medulla oblongata and ventral commissure of the 3rd ventricle. Other findings included vacuolar degeneration in the ganglia of the GI tract, salivary glands, prostate gland, uterus, and parathyroid glands. The pituitary gland showed edema and mitotic figures in the pars nervosa. These observations outside the CNS were seen in most rats at 90 and 150 mg/kg/day independent of study duration. At 30 mg/kg/day, most of these observations were only seen in isolated cases except for the vacuolar degeneration in GI tract ganglia, which was absent at this dose after 4 weeks treatment but was present in almost all rats at 13 and 26 weeks. Hepatocellular hypertrophy and nephropathy were seen across all studies and the extent of these changes was similar in the 13- and 26-week studies. Most findings resolved after the 4-week recovery periods except for the axonal swelling seen in the medulla oblongata and spinal cord. BIA 10-2474 exposure was markedly higher than the exposure to either metabolite, BIA 10-2445 (19- to 192-fold) and BIA 10-2583 (63- to 526-fold). Exposure to metabolites differed between sexes with higher concentrations of BIA 10-2445 in females compared to males, but the inverse for BIA 10-2583. Although a No Observed Adverse Effect Level (NOAEL) of 30 mg/kg/day was concluded following the 4-week study, the histopathological findings at that dose in the 13- and 26-week studies resulted in the NOAEL being determined to be 10 mg/kg/day.

We independently and retrospectively reviewed three studies that evaluated the toxicity of BIA 10-2474 (3-(1-(cyclohexyl(methyl)carbamoyl)-lH-imidazol-4-yl)pyridine 1-oxide), a novel fatty acid amide hydrolase (FAAH) inhibitor in male and female CD-1 mice based upon raw data obtained from Bial Portela & Companhia S.A. (São Mamede do Coronado, Portugal). These studies were carried out prior to the clinical trial with BIA 10-2474 and formed part of the regulatory submission. An initial oral dose range-finding study with BIA 10-2474 showed that doses from 600 mg/kg/day were poorly tolerated with a high mortality rate and signs of weakness, prostration, labored breathing, clear lacrimation, tachypnea/bradypnea and decreased activity. At lower doses (100 and 300 mg/kg/day) there were few signs but post-mortem analysis showed increased liver weight. In a 28-day study a third of the animals receiving 500 mg/kg/day died or required euthanasia, with similar signs to those seen in the dose-range finding study. At lower doses (i.e. 100 and 300 mg/kg/day) there were few clinical signs although there were dose-related decreases in erythrocyte count and hemoglobin. Histopathology was seen in the 300 and 500 mg/kg/day groups and included hepatocellular hypertrophy (with increased liver weight), nephropathy and enterocyte vacuolation. Finally, in the 13-week oral gavage study, BIA 10-2474 was administered to CD-1 mice of both sexes at dose levels of 25, 75 and 150 mg/kg/day. Under these conditions, there were almost no clinical signs apart from a tendency to increase body-weight. Cholesterol was increased at 75 and 150 mg/kg and remained high after recovery. Liver and spleen weights increased at 75 and 150 mg/kg/day. Histopathologically, there was a dose-dependent increase in sciatic nerve and myofiber degeneration, hepatocellular hypertrophy, nephropathy and inflammatory loci in the bladder. The nerve damage and nephropathy seen at 150 mg/kg/day persisted after a 4-week recovery period. Toxicokinetic analysis in the 4- and 13-week studies showed that exposure was broadly dose-proportional with no evidence of accumulation. On the basis of the changes seen during the 13-week study, the NOAEL was established at 75 mg/kg/day.

A series of regulatory studies were carried out to investigate the effects of the FAAH inhibitor BIA 10-2474 on fertility, embryo-fetal toxicity and pre- and post-natal development in rats and rabbits. Despite some reductions in sperm count in rats from 50 mg/kg, there were no major changes in male fertility up to 100 mg/kg. In female rats administered up to GD6, there were increases in pre-implantation loss at 50 and 100 mg/kg but neither post-implantation loss nor early embryonic development was affected. In contrast, when administered to female rats during pregnancy (GD6-GD17), BIA 10-2474 at 75 mg/kg/day reduced food consumption resulting in weight loss, increased post-implantation loss and reduced mean fetal body weight. In rabbits, the same maternal toxicity was seen but there were no effects in this species on post-implantation loss or fetal body weights. There were no teratological effects clearly due to BIA 10-2474 and developmental milestones and behavior of offspring were not affected. When administered during pregnancy and lactation (GD6-PND20), some post-implantation loss was seen from 20 mg/kg/day, but developmental milestones and behavior of the offspring were not affected, although males tended to have lower body weight. Based on these data the NOAEL for parental fertility was established as 50 mg/kg/day, the maternal NOAEL during pregnancy was 25 mg/kg/day in rats and developmental NOAEL was 25 and 75 mg/kg/day in rats and rabbits, respectively. When administered during post-natal development to rats the maternal NOAEL was 6 mg/kg/day. The parental reproductive NOAEL, the NOAEL for viability and growth of the F1 offspring, the F1 parental NOAEL and the F1 reproductive NOAEL were all considered to be 20 mg/kg/day.

BIA 10-2474 is a novel fatty acid amide hydrolase inhibitor developed for the treatment of medical conditions which would benefit from enhanced levels of endogenous anandamide (AEA) such as pain disorders. During a Phase I clinical trial one subject died after receiving BIA 10-2474 and others displayed neurological signs. We describe here the toxicology studies in beagle dogs that supported phase I testing of BIA 10-2474 in humans. A Maximum Tolerated Dose (MTD) study using once-a-day oral (capsule) application of BIA 10-2474 was first conducted to establish suitable dose levels for subsequent studies. Based on these results, 100 mg/kg/day was considered to be the MTD. The 4-week oral (capsule) toxicity study with a 3-week recovery period for BIA 10-2474 was therefore carried out at 20, 50 or 100 mg/kg/day. There were no changes recorded at 50 mg/kg/day and this was considered the oral No Observed Effect Level (NOEL) for four-week once-a-day capsule administration to Beagle dogs. At 100 mg/kg/day, the dose-limiting findings consisted of clinical symptoms including tremor, loss of balance, abnormal gait, decreased motor activity, weakness, vomits, salivation increase and miosis, increased severity of thymic atrophy/involution, and moderate acute, focal/multifocal bronchopneumonia in lungs of three animals. In a 13-week oral (capsule) toxicity study in the Beagle dog with a 6-week recovery period, using the same dose levels, clinical signs were recorded during treatment with BIA 10-274 at 50 and 100 mg/kg/day. The most frequent signs included difficulty breathing, respiratory sounds (with or without auscultation) and cough. Incoordination of the hind limbs with absence of correction reflex were also observed on some occasions. As a result, the 50 and 100 mg/kg/day doses were reduced to 35 and 50 mg/kg/day respectively on day 37. Because of the continued signs, the doses in both groups were further reduced to 20 mg/kg/day from day 77. Under the conditions of this study and given the severe signs recorded in groups treated at 100-50-20 and 50-35-20 mg/kg/day and only very occasional presence of signs in the group treated for the 13-week period at 20 mg/kg/day (abnormal respiratory sounds once in two animals), the dose of 20 mg/kg/day was considered the No Observed Adverse Effect Level (NOAEL).

(2R,4R)-Monatin salt [sodium/potassium 2R,4R-2-amino-4-carboxy-4-hydroxy-5-(3-indolyl) pentanoate] was fed at 5000, 15,000, or 35,000 ppm to Crl:CD(SD) rats over two generations. Reduced body weights were observed at all dose levels. Sustained effect on body weight gain at 35,000 ppm in the F0 and F1 parental animals was associated with lower feed efficiency, soft stool, and slightly lower numbers of implantation sites. Lower numbers of pups born and live litter size at 35,000 ppm were considered secondary to slightly lower numbers of former implantation sites in the dams. Spermatogenic endpoints, estrous cyclicity, reproductive performance, mean gestation length, and parturition were unaffected in the F0 and F1 generations. There were no effects on F1 and F2 generation postnatal survival. Reduced pre-weaning pup body weights at 35,000 ppm resulted in lower F1 and F2 body weights at study termination. Slight delays in pubertal landmarks in the F1 offspring were considered secondary to the reduced pup body weights. The no-observed-adverse-effect level (NOAEL) was 15,000 ppm for systemic, reproductive, and neonatal effects based on test article-related effects on body weight and food efficiency, slight decrease in maternal implantation sites and corresponding reduction in live litter size, and reductions in pre-weaning pup body weights at 35,000 ppm.

(2R,4R)-Monatin salt (Na/K) [sodium/potassium (2R,4R)-2-amino-4-carboxy-4-hydroxy-5-(3-indolyl) pentanoate, hereafter "R,R-monatin"] was administered in the diets of groups of Beagle dogs (4/sex/group) at concentrations of 0 (basal diet), 5000, 20,000, or 35,000 ppm for 13 weeks. There were no effects on survival, clinical observations, body weight and body weight gain, feed consumption and feed efficiency, functional observational battery, ophthalmic examination, and electrocardiographic evaluation. No adverse effects on hematology, serum chemistry, and urinalysis parameters were reported. A statistically significant decrease in testicular weights associated with germ cell hypocellularity and reduced luminal sperm in the epididymides was reported in all treated male groups. Based on these findings, the dietary no-observed-adverse-effect level (NOAEL) of R,R-monatin for 90 days was considered 35,000 ppm for female dogs (approximately 1101 mg/kg bw/day) and <5000 ppm for male dogs (approximately <151 mg/kg bw/day).

Reproductive and developmental toxicity studies in laboratory animals are conducted as part of the process of evaluating the risk of pharmaceuticals and chemicals to human reproduction and development. In these studies, comparison of data from groups dosed with the test article to a concurrent control group is considered the most relevant approach for the interpretation of adverse effects. However, differences between the concurrent control and treated groups may arise by chance alone, and in some instances may even appear to be dose-related. These limitations of the concurrent control group are of particular concern when interpreting fetal malformation data because malformations are rare events that can be better characterized when incidences in both concurrent control and treated groups are compared to a larger set of control values. Historical control data can be useful not only to understand the range of normal for a given endpoint but also to monitor the biological variability over time due to various external factors (e.g., genetic changes in a strain, changes at the breeding facility). It can also serve to track the performance of the laboratory and identify any changes in the data that may be the result of internal factors at the performing laboratory due to modification in animal diet, seasonal changes, or even the proficiency of the technicians in handling animals and recording fetal and offspring observations. This chapter will provide the reader with guidance on building a laboratory historical control database and applying it to the scientific interpretation of reproductive and developmental toxicity data. Information on sources of external historical control data will be provided and some perspective given on the utility of this data. A discussion of the presentation of historical control data with descriptive statistics will be accompanied by examples of tabulation of the data. Supernumerary rib will be used as an example of how historical control data can be used for data interpretation.

To evaluate whether methyl isobutyl ketone (MIBK) affects reproductive performance, a two-generation reproduction study was conducted. MIBK was administered to 30 Sprague-Dawley rats/sex/group via whole-body inhalation at concentrations of 0, 500, 1000, or 2000 ppm, 6 h daily, for 70 days prior to mating. F(0) and F(1) females were exposed from mating through gestation day 20 and from postnatal day 5; F(2) litters were maintained through postnatal day 21. No treatment-related mortality of adult animals occurred. There was a dose-related increase in adult animals with no or a decreased response to a sound stimulus at 1000 and 2000 ppm; however, no adverse clinical signs occurred 1 h after exposure, suggesting this was a transient sedative effect. Clinical signs of central nervous system (CNS) depression in the pups were observed and one F(1) pup died after initial exposure to 2000 ppm on postnatal day 22; subsequently exposure was delayed until postnatal day 28. Decreased body weight gain and slight decreased food consumption were observed during the first 2 weeks of exposure in both generations at 2000 ppm. There were no adverse effects on male and female reproductive function or landmarks of sexual maturation. Increased F(0) and F(1) liver weights with associated centrilobular hypertrophy occurred in rats at 2000 ppm, indicative of an adaptive response. Increased male kidney weights at all exposure concentrations, associated with hyaline droplets, were indicative of male rat-specific nephropathy. Other than acute sedative effects, the no-observed-adverse-effect level (NOAEL) for parental systemic effects (excluding male rat kidney) was 1000 ppm, based on transient decreased body weight and food consumption; for reproductive effects, 2000 ppm, the highest concentration tested; and for neonatal toxicity, 1000 ppm (based on acute CNS depressive effects).

The potential reproductive toxicity of di-isononyl phthalate (DINP: CAS RN 68515-48-0) was assessed in one- and two-generation reproductive toxicity studies. Groups of 30 male and female CRL : CD(SD)BR rats were given DINP via dietary administration at levels of either 0.0, 0.5, 1, or 1.5% (one-generation study) or 0.0, 0.2, 0. 4, or 0.8% (two-generation study). There were no changes in any of the classic reproductive parameters, i.e. mating, male or female fertility, fecundity, gestational index, or length of gestation in either study. The overall NOAELs for these effects were the highest Dietary Level (%)s tested, approximately 500 mg/kg/day in the two-generation study and 1000 mg/kg/day in the one-generation study. There were no testicular effects in parental animals exposed as juveniles and young adults at 960 mg/kg/day in the one-generation study. In the two-generation study, there were no testicular effects in either the P(1) males, exposed as juveniles and young adults or the P(2) (F(1)) offspring exposed in utero, through lactation, and continuously to terminal sacrifice. The NOAEL was 470 mg/kg/day. Offspring survival was reduced at the 1.5% level ( approximately 1100 mg/kg/day) but unaffected at the 1% level ( approximately 760 mg/kg/day). There were decreased offspring body weights both at postnatal day (PND) 0 and during lactation; however, the PND 0 effects were only clearly related to treatment at the 1.5% level. Weights of offspring during lactation were significantly reduced but within the historical control range at Dietary Level (%)s below 1%. As there was rapid recovery at the lower levels, even though treatment continued, the toxicologic significance is unclear. Adult survival was unaffected at any level in either study, but weight gain was significantly reduced at the 1% level ( approximately 600 mg/kg/day). Liver and kidney weights were elevated at Dietary Level (%)s above approximately 110 mg/kg/day, consistent with evidence from other studies of peroxisomal proliferation at these levels. This study showed that DINP treatment does not affect fertility or male reproductive development at doses of up to approximately 1000 mg/kg/day.

The developmental toxicity of di-isodecyl phthalate (DIDP; CAS RN 68515-49-1) and di-isononyl phthalate (DINP; CAS RN 68515-48-0) were investigated in Sprague–Dawley rats. DIDP and DINP were administered by gavage to mated rats at doses of 0, 100, 500, and 1000 mg/kg/d on Gestation Days (GD) 6 through 15. Cesarean sections were performed on GD 21 and the fetuses removed for evaluation. Maternal weight gain and food consumption were significantly reduced at 1000 mg/kg/d during the exposure period. No treatment-related effects were noted at cesarean section, nor were there any fetal morphologic observations except for an increased frequency of seventh cervical and rudimentary lumbar ribs at the maternally toxic exposure level of 1000 mg/kg/d. Under these study conditions, mild maternal and developmental effects were observed at 1000 mg/kg/d. Both maternal and developmental NOAELs were therefore established at 500 mg/kg/d. The results indicate that neither DIDP nor DINP is teratogenic or a selective developmental toxicant.

The complex physiological interactions among a pregnant mammal, her embryos, and their placentae pose considerable challenges to investigators who conduct safety tests for the assessment of potential developmental toxicity. Many individuals who review developmental toxicity safety tests are not trained in this specialized area of toxicology. This paper presents a concise introduction to the science that underlies developmental toxicology for those individuals. The purpose of the paper is to educate the reader about appropriate test procedures, the types of data that are collected, and evaluation of studies. To these ends, the paper explains important terminology and study designs' makes comments concerning what should be considered acceptable developmental toxicity data; and provides insights and rules of thumb regarding the evaluation and interpretation of the data.

To the Editor: A 1993 article published in the Journal of the American College of Toxicology (Christian MS. Problems in developmental toxicity caused by incorrectly used terminology. J Am Coll Toxicol 19!33;12:323-8) has elicited a rather vigorous Letter to the Editor. As I am the Developmental and Reproductive Toxicology Section Editor of the Journal and a person mentioned in the original article, the Editor-in-Chief has asked that I add an additional perspective on what to him seemed a valuable article. Dr. Christian’s article emanated from her platform presentation in an ACT symposium on the topic of terminology problems in developmental toxicology. Her writing highlights and briefly illustrates some difficulties generated by our general lack of agreed-upon definitions for the terminology we all use. She points out that (a) different languages can provide different connotations to some scientific terms andor lack of terms present in other tongues and (b) different regulatory agencies, courtrooms, and even individual pregnant women view agent safety differently based on the presence or absence of terata in a standard animal test and may do so to an extent that this finding overshadows other signs of perturbed in utero development or even exposure intensity. The above observations are followed by a brief historic and contemporary series of referenced practical situations she and others have encountered. The examples are well chosen and make interesting reading through illustrative examples most of us have encountered over the years. The last page of the article provides a historic background of EPA, MARTA, JTS, and ETS efforts at resolution of nomenclature problems across venues and languages and concludes with an aspiration for IFTS consideration of this topic. The letter to the editor submitted by Dr. De Sesso et al. considers that Dr. Christian lays the “blame” for incorrect terminology on Dr. James Wilson. Their letter opines that Dr. Christian is incorrect in doing so on three bases: (a) The FDA Segment I1 study really is a teratology study; (b) this terminology, i.e., “teratology study,” did not result in an exclusion of other forms of embryotoxicity; and (c) if calling the standard developmental toxicity study a “teratology study” was a misnomer of great impact, it would not have taken two decades for the problem to be raised. The first and last paragraphs extol some of Dr. Wilson’s many virtues and abilities, but seem to do so as though his reputation needs defense from anyone. They conclude that he provided inspiration and scientific insight and that a misperceived sin of incorrect terminology is not his legacy. My reading of the original article is that Dr. Christian also extolled the virtues of Dr. Wilson, but chose her words incautiously: i.e., in considering that others understood the axioms involved, he made a “communication error.”

A single injection of 20 mg/kg methylazoxymethanol acetate (MAM) on gestational day 14 in Brown Norway rats produced micrencephalic offspring (whole brain ≈65% of control). Despite the micrencephaly, MAM-induced alterations in behavior assessed here were relatively mild. The MAM-treated rats exhibited increased activity under darkened conditions in a complex maze and marginally increased activity after a challenge of methamphetamine. Open field activity, running wheel activity, and emergence behavior using a light/dark apparatus were not significantly affected. Compared with a similar study of Sprague–Dawley micrencephalics [Ferguson S. A., Racey F. D., Paule M. G. and Holson R. R. (1993) Behavioral effects of methyloxymethanol-induced microencephaly. Behav. Neurosci.107, 1–10], frontal cortex and striatum weights were more reduced in Brown Norway micrencephalics. The MAM-induced behavioral alterations in the Brown Norway strain may have appeared attenuated compared to alterations shown by MAM-treated Sprague–Dawley rats due to differences in baseline behavior between these two strains. Compared to control Sprague–Dawley rats in the previous study, control Brown Norway rats were more active in the open field and running wheels, but less active in the complex maze, exhibiting little to no learning. Emergence tests indicated increased dark preference in Brown Norway rats. Baseline behavior (increased activity and light shyness) of control Brown Norway rats was similar to that of MAM-treated Sprague–Dawley rats; a potential confound in the detection of behavioral effects of a compound. These findings emphasize the effects that strain selection may have on the outcome and interpretation of toxicological/teratological studies.