Polarizing microscopy of birefringent lipids in rabbit fetal lungs.
The development of birefringent lipids in pre- and postnatal rabbit lungs was studied by polarizing microscopy (PM) and correlated with transmission electron microscopy (TEM). Birefringent lipids first appeared as small scattered particles in the developing alveolar walls at 27 days of gestation. These particles became aggregated, gradually increased in amount in older fetuses, and reached a prenatal maximum at 30 days. Numerous particles were located in the alveolar lumen, beginning in the 30-day fetuses. Further increase in the amount of birefringent lipids occurred in the 60-day-old rabbits. TEM demonstrated cytoplasmic lipid inclusion bodies in the type II pneumocytes at 25 days of gestation. Some of these inclusions were lamellated, but regular lamellated bodies were often seen in older fetuses. It appears that the development of birefringent lipids is closely correlated with the development of lamellated bodies seen with TEM, and PM is a simple, useful method in following the development and maturation of surfactant lipids.
D000818:Animals; D001718:Birefringence; D005333:Fetus / Q000033:anatomy & histology*; D005865:Gestational Age; D008055:Lipids / Q000502:physiology*; D008168:Lung / Q000196:embryology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008859:Microscopy, Polarization; D011817:Rabbits / Q000196:embryology*
D008055:Lipids