The acute inflammatory response of the fetal rhesus monkey was studied as a function of age and the cellular response of the fetus characterized by light and electron microscopy. Thirteen sexually mature female rhesus monkeys (Macaca mulatta) were laboratory bred, and the fetuses received injections subcutaneously in utero at 60, 90, 120, or 150 days of gestation of turpentine, bacterial lipopolysaccharides, heat killed Staphylococcus aureus, and immune complexes. Injection sites were sampled 4 and 24 hr after inoculation. In addition, 3 newborn and 2 yearling rhesus monkeys were compared with the fetal groups. The earliest lesion observed was in the 90 day fetus, 24 hr after injection of turpentine. Small mononuclear cells predominated in this lesion and, with advancing fetal age, polymorphonuclear cells and fibrin became characteristic features. Fetal animals administered 100 μg of lipopolysaccharides subcutaneously died 8 to 24 hr after injection, with an absence of morphologic lesions. Newborn and yearling animals responded to lipopolysaccharides with a lesion closely resembling a localized Shwartzman reaction. Fetal response to heat killed Staphylococcus aureus and immune complexes was not observed until 24 hr after injection at 150 days gestation, and then the cellular response was primarily mononuclear, with occasional polymorphonuclear cells present. Fetal reactivity to various irritants differs from that of the adult. The essential differences were that a mononuclear cell infiltrate was the earliest response in the young fetus; polymorphonuclear cells were absent or present in extremely low numbers in the young fetus, polymorphonuclear cells when present in older fetuses responded slowly, and edema and fibrin were absent in lesions during early fetal life.
|Original language||English (US)|
|Number of pages||13|
|State||Published - Dec 1 1974|
ASJC Scopus subject areas
- Pathology and Forensic Medicine
- Molecular Biology
- Cell Biology