TABLE.

Histology of placenta after IV inoculation with M pulmonis

	Number of placenta	Deciduitis mean rank	Mean lesion ± SD
Control	13	26.654a	1.54 ± 0.22
101 dose	11	33.591b	1.82 ± 0.23
103 dose	17	32.088b	1.77 ± 0.16
105 dose	14	36.607b	1.93 ± 0.22
107 dose	25	58.64c	2.76 ± 0.12

Dams were inoculated at GD 14 and necropsied on GD 18. Dams were inoculated IV with 0, 10¹, 10³, 10⁵, or 10⁷ CFU infective dose of M pulmonis diluted in sterile Frey’s broth. Placentas from at least 3 fetal units per dam were randomly selected from each dose. Tissue sections containing decidua, chorion and amnion were processed and stained with hematoxylin and eosin (H&E). Tissues were scored for deciduitis based on (1) no neutrophilic infiltration, (2) moderate neutrophilic infiltration, (3) severe neutrophilic infiltration, neutrophil degradation and presence of mononuclear cells. There was a significant difference in mean ranks for deciduitis among doses (P = .0001).

Riggs. Hematogenous infection of Sprague-Dawley rats with Mycoplasma pulmonis. Am J Obstet Gynecol 2008.

^a,b,cMean ranks with the same symbol are not significantly different from each other.