PMID- 8935784
OWN - NLM
STAT- MEDLINE
DCOM- 19970122
LR  - 20131121
IS  - 0260-437X (Print)
IS  - 0260-437X (Linking)
VI  - 16
IP  - 2
DP  - 1996 Mar-Apr
TI  - Supernumerary lumbar rib: manifestation of basic alteration in embryonic 
      development of ribs.
PG  - 115-9
AB  - Supernumerary ribs (SNR) are a common variant in some strains of mice used in 
      standard teratology bioassays. We have previously demonstrated that increased 
      incidence of SNR may be induced by a wide variety of xenobiotics and/or general 
      maternal stress. The significance of this defect in cross-species extrapolations 
      has been problematic and recent studies, including this one, have shown that this 
      anomaly is more complex than previously thought. The SNR in mice have a bimodal 
      distribution composed of 'rudimentary ribs' (RR) with a mode of 0.3-0.4 mm and 
      'extra ribs' (ER) with a mode of 0.9-1.1 mm. The studies reported here examine 
      the relationship between the presence of SNR and the 13th rib length and the 
      gross morphological development of the anomaly. Supernumerary ribs were induced 
      in CD-1 mice by surgical stress (subcutaneous micropump implanted on gestational 
      day (GD), restraint stress (GD8), food and water deprivation (GD8) or maternal 
      administration of the pesticide dinoseb (50 mg kg-1 on GD7 and GD8). Fetuses from 
      untreated litters were also examined. Dinoseb-treated mice were killed on GD14, 
      15, 16 or 17. All other groups were killed on GD17. The lengths of the 13th and 
      14th ribs were measured and other anomalies were recorded. Femur length was used 
      as an indicator of fetal size. The SNR frequency was higher in all treatment 
      groups compared to controls. We found that ER and RR were morphologically 
      distinct. The ER were flat ended and distally joined by a cartilaginous portion, 
      while RR were usually rounded distally and were without cartilaginous extensions. 
      The 13th ribs were significantly longer in fetuses having SNR than in those not 
      having SNR, whether treated or untreated. This relationship was present in all 
      fetal ages examined and with both ER and RR groups. These results suggest that 
      SNR are indicative of basic alterations in the development of the axial skeleton.
FAU - Branch, S
AU  - Branch S
AD  - Health Effects Research Laboratory, Environmental Protection Agency, Research 
      Triangle Park, NC 27711, USA.
FAU - Rogers, J M
AU  - Rogers JM
FAU - Brownie, C F
AU  - Brownie CF
FAU - Chernoff, N
AU  - Chernoff N
LA  - eng
PT  - Comparative Study
PT  - Journal Article
PL  - England
TA  - J Appl Toxicol
JT  - Journal of applied toxicology : JAT
JID - 8109495
RN  - 0 (Pesticides)
RN  - Q13SKS21MN (2,4-Dinitrophenol)
RN  - YD44ZEM22M (dinoseb)
SB  - IM
MH  - 2,4-Dinitrophenol/*analogs & derivatives/toxicity
MH  - Abnormalities, Drug-Induced/*embryology
MH  - Animals
MH  - Fasting
MH  - Female
MH  - Gestational Age
MH  - Mice
MH  - Pesticides/*toxicity
MH  - Pregnancy
MH  - Ribs/*abnormalities
EDAT- 1996/03/01 00:00
MHDA- 2000/06/20 09:00
CRDT- 1996/03/01 00:00
PHST- 1996/03/01 00:00 [pubmed]
PHST- 2000/06/20 09:00 [medline]
PHST- 1996/03/01 00:00 [entrez]
AID - 10.1002/(SICI)1099-1263(199603)16:2<115::AID-JAT309>3.0.CO;2-H [pii]
AID - 10.1002/(SICI)1099-1263(199603)16:2<115::AID-JAT309>3.0.CO;2-H [doi]
PST - ppublish
SO  - J Appl Toxicol. 1996 Mar-Apr;16(2):115-9. doi: 
      10.1002/(SICI)1099-1263(199603)16:2<115::AID-JAT309>3.0.CO;2-H.