title: Developmental variation of the diaphragm and liver in Fischer 344 rats.
abstract: The nature and frequency of a developmental variation of the diaphragm and liver in Fischer 344 rats are described. Totals of 20, 98 and 55 (25 for caesarean-sectioning and 30 for natural delivery) mated female rats were used for Experiments 1, 2, and 3, respectively. Each rat was intubated (gavage) with either an aqueous suspension of 0.2% METHOCEL, 0.25% methyl cellulose, or distilled water as a single daily dose from days 6 through 15 (inclusive) of gestation. On the 20th day of gestation, a caesarean-section was performed, and the uterine contents of each rat were examined. A gross necropsy was performed on the pups of 30 mated female rats on day 21 postpartum. The visceral examinations conducted on these fetuses and pups included an evaluation of a developmental variation in the diaphragm and liver. The variation consisted of a thin fibrous central tendon of the diaphragm with an area of liver (0.5-3 mm diameter) that protruded within the thin central tendon of the diaphragm. The incidence (mean % of fetuses affected per litter) of the diaphragm/liver developmental variation was 9% and 11% for METHOCEL- and water-treated groups, respectively. A thin central tendon was present in the diaphragm of all fetuses of methyl cellulose-treated dams; these fetuses did not have a raised area of the liver present within the diaphragm's central tendon. However, in a few weaned pups of the Fischer 344 rats in this study, liver protruded within the central tendon of the diaphragm.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: H.S. & E., Toxicology Department, Shell Oil Company, Houston, Texas 77210.
authors.forename: C C
authors.initials: CC
authors.lastname: Lu
authors.forename: R L
authors.initials: RL
authors.lastname: Mull
authors.forename: E A
authors.initials: EA
authors.lastname: Lochry
authors.forename: M S
authors.initials: MS
authors.lastname: Christian
mesh_terms: D000818:Animals; D003964:Diaphragm / Q000187:drug effects / Q000196:embryology*; D010064:Embryo Implantation; D005260:Female; D008098:Litter Size; D008099:Liver / Q000187:drug effects / Q000196:embryology*; D008297:Male; D008747:Methylcellulose / Q000494:pharmacology*; D008954:Models, Biological; D011247:Pregnancy; D051381:Rats; D011916:Rats, Inbred F344; D012016:Reference Values; D013723:Teratogens
chemical_list: D013723:Teratogens; D008747:Methylcellulose