Morphological observations of the fetal rat spleen during prolonged gestation.
The ultrastructure of splenic cells and frequency of cell types were examined in fetal rats during progesterone-induced (P23, 24, 25) and surgically-induced (S23, 24, 25) prolonged gestation, and compared to term (T) fetuses and newborn animals (N1, N2, N3). Statistical analysis revealed an increase in numbers of erythroblasts and a decrease in numbers of neutrophils in post-term fetuses distinct from that seen in term and newborn animals. However, there were also significant differences between the post-term groups: the frequency of erythrocytes and total number of cells were higher in the drug-treated group, despite similar splenic weights in the two. The results are interpreted as a response by the spleen (increased erythropoiesis) to fetal hypoxia, which is known to exist during prolonged gestation.
D000818:Animals; D000831:Animals, Newborn / Q000033:anatomy & histology; D005260:Female; D008854:Microscopy, Electron; D011247:Pregnancy; D011273:Pregnancy, Prolonged; D051381:Rats / Q000196:embryology*; D013154:Spleen / Q000166:cytology / Q000196:embryology* / Q000648:ultrastructure