TABLE 3.

Summary of structural changes in pars flaccida and fossa nasalis in relation to time and challenge group^a

Day	Category	Histological findings				Category assignment by challenge groupb
		Inflammatory cells	Metaplasia	Epithelial proliferation	Vessel reaction
3 (prior to ab)	Moderate changes	++	++	NA	++	A, n = 1/3; B and C, n = 2/3
	Major changes	+++	++/+++	NA	++	A, n = 2/3; B and C, n = 1/3
8	Moderate changes	+	+/++	0	+	A, n = 2/3; B, n = 1/3
	Major changes	++	++/+++	++	++	A, n = 1/3; B, n = 2/3; C, n = 3/3
56	No or minor changes	0	0/+	0	+	A, n = 3/6
	Moderate changes	0/+	+/++	++	++	A, n = 3/6; B, n = 1/4; C, n = 2/5
	Major changes	++	++/+++	++/+++	++	B, n = 3/4; C, n = 3/5

^aAbbreviations 0, no changes; +, minor changes; ++, moderate changes; +++, extensive changes, NA, not applicable; ab, antibiotic treatment.

^bA, S. pneumoniae infection and antibiotic treatment; B, S. pneumoniae and H. influenzae infections and antibiotic treatment; C, S. pneumoniae and H. influenzae infections and antibiotic trea tment. The data (n values) indicate the number of animals in the group/total number of animals.