Ultrastructure of pulmonary macrophagic system.
A mature AMF, ready for phagocytosis, is a relatively large cell with an oval nucleus, with indentations of a nuclear envelope of varying depth. Evenly distributed chromatin forms beneath the nuclear envelope a rim of heterochromatin. There is a prominent nucleus with a distinct nucleolonemma. The cytoplasm is differentiated into a continuous ectoplasmic zone with numberous finger-like processes and pseudopodia. The organelles are formed by scattered round or oval mitochondria, a description is given of the Golgi apparatus in the juxtanuclear position, in certain sites multifocal in form, of the centriolar apparatus, scarce profiles of endoplasmic granular reticulum, dispersed free polyribosomes and microfilaments in varying amounts. The most outstanding feature is the rich lysosomal apparatus of varying structure depending on the functional state. Dynamics of the maturation of AMF was studied in intermediate phases, described here. The peribronchovascular connective tissue is the seat of free macrophages of a structure analogous with that of AMF. Fixed macrophages are anchored in the loose connective tissue by processes of different shape and length. The prevailing component of the cytoplasm are numerous vesicular structures and vacuoles as well as a marked lysosomal apparatus. Fixed macrophages phagocytize foreign material in situ. The septal cell exists in normal state as an element with numerous intricated processes pervading the fibrillar substrate. Numerous free polyribosomes and vacuoles are its most marked component. Activation of septal cells was demonstrated under experimental conditions. Their transformation into free macrophages is probable. In the pulmonary intersitium, in the perivascular loose connective tissue particularly free cells of a similar structure as blood monocytes were shown in normal state. Under experimental conditions an increased number of monocytes is present in pulmonary capillaries, e.g. 24 hours after an intratracheal instillation of India ink colloid solution. At the same interval a number of free cells of the monocyte structure was found in the perivascular connective tissue and also in the alveolar lumen, with phagocytized carbon. An increased number of monocytes transforming into macrophagic cells was visualized in this localization as late as 14 days after the instillation of India ink colloid solution. The experimental study with an intratracheal instillation of India ink colloid solution in the mouse gave evidence of a high readiness of AMF. The carbon particles were seen phagocytized at an interval of 5 minutes after instillation. In all intervals during which free carbon particles were present in the alveolar epithelium mature AMF were observed with no or very low phagocytic activity, their lysosomal apparatus being prominent. On the contrary, in the phagocytizing AMF, the lysosomal apparatus disappeared in the greatest part of the cytoplasm. The clearance of AMF occurs predominantly by the air route...
D000818:Animals; D003411:Arvicolinae; D002196:Capillaries / Q000648:ultrastructure; D002465:Cell Movement; D002466:Cell Nucleolus / Q000648:ultrastructure; D002467:Cell Nucleus / Q000648:ultrastructure; D003238:Connective Tissue / Q000648:ultrastructure; D003239:Connective Tissue Cells; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D006056:Golgi Apparatus / Q000648:ultrastructure; D000882:Haplorhini; D006801:Humans; D008168:Lung / Q000648:ultrastructure; D008247:Lysosomes / Q000648:ultrastructure; D008264:Macrophages / Q000502:physiology / Q000648:ultrastructure*; D051379:Mice; D008854:Microscopy, Electron; D008928:Mitochondria / Q000648:ultrastructure; D009000:Monocytes / Q000648:ultrastructure; D010587:Phagocytosis; D011554:Pseudopodia / Q000648:ultrastructure; D011650:Pulmonary Alveoli / Q000098:blood supply / Q000648:ultrastructure*; D011817:Rabbits