Electron microscopical observations on the function of the tracheal epithelium, with special reference to ciliated cells

The epithelium lining of trachea and lung in rats and mice after administration of 5<i>% </i>dextran iron solution, ferritin and charcoal particles were investigated with the aid of electron microscopy. An enzyme for fluid transport, adenosine triphosphatase, has also been studied by electron microscopy. The microvilli in ciliated cells of the trachea increased in their number after administration of foreign substances, and many micropinoeytosis vesicles take up the ferritin into the ciliated cells but no dextran iron particles were found within the ciliated cell. A large amount of charcoal particles were observed within the ciliated cells with no cilia in cases of inspiration for long hours. All tracers used in this study were found within (he alveolar epithelial cells, so-called dust cells and capillary endothelial cells in lung. ATPase activity could be demonstrated on the surface of the microvilli and cell membrane of ciliated cells but not on cilia.

The development of the sensory epithelium of the cristae ampullares in the rabbit

Phase contrast and electron microscopy was used to study the maturation of the sensory epithelia in the cristae ampullares in the rabbits. The sensory cells differentiate from the simple cylindrical cells at the time their nerve endings make synaptic contact. The afferent nerve endings in the hair cells type II have been first appeared. Then the efferent innervation in the hair cells type II and nerve chalice formation in the hair cells type I have been occurred at birth. The significance of this findings was discussed.

A study of the function of the stria vascularis and spiral ligament in each cochlear turn

The distribution of radioactive sodium (²²Na) and phosphorus (³²P) and oxygen consumption in the stria vascularis and spiral ligament of guinea pigs was studied. The concentration of ³²P in the stria vascularis with spiral ligament in each turn 24 h after the injection decreased from the basal turn to the apical turn. The concentration of ³²P in the stria vascularis was approximately similar to that in the spiral ligament. The concentration of the radioactive isotope 24 h following the injection of ²²Na in the stria vascularis with spiral ligament in the middle turn appeared higher than that of the other turns. The concentration of ²²Na in the stria vascularis was higher than that in the spiral ligament. The oxygen consumption in 0.2% glucose Krebs Ringer phosphate solution of the spiral ligament as well as the stria vascularis was high. A view of the function of the stria vascularis and spiral ligament and endolymph formation were discussed.

An electron microscopic study of the human fetus cochlea

Electron microscopic observations were made of the cochlea in 5–6 month human fetus and 22–30-day rabbit fetus. The hair cells, supporting cells and afferent nerve fibers and endings can be identified among the rows of columnar cells that constitute the organ of Corti in 5–6 month human fetus. Intercellular fluid spaces and efferent nerve endings were not found in the human specimens studied here. The layer of cells next to endolymph in the stria vascularis, the future marginal cells, are separated from the cells beneath by a distinct basement membrane at the early stage of development. Later the basement membrane disappears as the mesodermal cells beneath begin to interdigitate with the marginal cells. A single kinocilium is present on the endolymphatic surface of the cells in the immature cochlea. These findings were correlated with the rabbit fetus cochlea and it is suggested that the last major event that the organ of Corti has, to begin to carry out its auditory function, efferent innervation, would occur in the later stages of human uterine life.