The course and morphology of efferent nerve fibres in the papilla basilaris of the pigeon (Columba livia).

This paper describes the course and morphology of efferent fibres in an avian cochlea. Horseradish peroxidase stained efferent fibres in the pigeon papilla basilaris were identified by Nomarski optics and camera lucida drawings. There are at least two types of efferent fibres: Large thick fibres take mainly a transversal course and contact short and intermediate hair cells over the free basilar membrane as well as hyaline cells. Large efferent fibres contact both hair cells and hyaline cells. Small thin fibres contact short or intermediate hair cells over the free basilar membrane or tall hair cells over the neural limbus. A physiological consequence of the findings is that efferent activity will concomitantly lead to a contraction of hyaline cells and a hyperpolarization of hair cells.

[Second multicenter study of thrombocytapheresis using the Fresenius AS104 blood cell separator and ring study for quality control of cell counts. Members of the Preparative and Therapeutic Hemapheresis Section of DGTI]. / Zweite Multizentrische Studie zur Thrombozytapherese mit dem Blutzellseparator Fresenius AS 104 und Ringstudie zur Qualitätskontrolle der Zellzählung. Mitglieder der Sektion Präparative und Therapeutische Hämapherese der DGTI.

The aim of the 2nd Multicenter study was to evaluate the separation protocol software version V 4.61 of the Fresenius AS 104 cell separator, for separation efficiency, WBC contamination and yield's deviation from prediction. Plateletpheresis data from 12 hemapheresis centers, using identical apheresis protocols and cell counting methods, were registered and statistically analyzed. Additionally, the counting methods of the centers were controlled by a ring study with biweekly cell counts. To get a comparison the apheresis data, which were dependent of the center effects, were corrected by the systematical deviation found in the quality control from the ring study. The results of 935 runs are 47.3 +/- 8.1% for the separation effectivity. 7.2% median deviation from predicted yield, whereby 90% of all runs deviated less than +/- 22% from predicted yields. 50% of products had a WBC contamination below 6 x 10(6), 99% below 5 x 10(7).

The influence of DC-polarization of the endocochlear potential on single fibre activity in the pigeon cochlear nerve.

The endocochlear potential (EP) in the pigeon ear was altered by injecting current into the scala media. Simultaneous recordings from afferent fibres in the cochlear ganglion were performed. The mean rate of spontaneous activity was little affected by current injection and the consequent shifts in EP. In contrast to this lack of effect, the preferred intervals seen in some fibres in birds were accentuated by positive current injection and reduced or in some cases suppressed by negative current injection. The threshold of the tuning curve was raised by injection of negative current but the characteristic frequency showed little change. Sharpness of tuning decreased. Analysis of the results shows that current injection in the scala media produces significant changes in the filter characteristics of the cochlea, as well as altering the driving force for the transduction process (difference between EP and hair cell membrane potential).

A previously unknown hair cell epithelium in the pigeon cochlea: the papilla chaotica.

A previously unknown sensory epithelium can be found on the medial wall of the apical part of the pigeon cochlear duct. It comprises about 200 hair cells. These are not arranged in any regular pattern, shape and orientation of the ciliary bundles even differ in neighbouring hair cells. We therefore propose the term papilla chaotica.

Furosemide has no effect on endocochlear potential and tuning properties of primary afferent fibres in the pigeon inner ear.

In the pigeon no influence of high doses (135 mg/kg) of furosemide on endocochlear potential and sound evoked activity in single auditory nerve fibres was found. This finding contrasts strongly to results in mammals.

Origin of infrasound sensitive neurones in the papilla basilaris of the pigeon: an HRP study.

Infrasound sensitive afferent fibres recorded in the pigeon cochlear ganglion were marked by intracellular injections of horseradish peroxidase (HRP). All stained fibres were found to innervate hair cells in the basilar membrane between 90 and 950 microns from its apical end. No fibres to the macula lagenae were found. Nine of the 10 completely stained fibres contacted hair cells located abneurally on the free basilar membrane, the tenth ended over the neural limbus near its abneural border. All fibres innervated between two and nine hair cells. This is in contrast to common auditory fibres in the bird that were reported to innervate only one hair cell located neurally over the neural limbus. This paper, therefore, demonstrates, for the first time, physiologically defined fibres that do not end on 'inner' hair cells.

Infrasound sensitive neurones in the pigeon cochlear ganglion.

The cochlear ganglion of the pigeon contains neurones sensitive to sound frequencies below 20 Hz (infrasound). They are characterized by a high spontaneous discharge rate (mean 115 imp/s). In contrast to ordinary auditory units, the mean discharge rate of these neurones is not increased by infrasound or sound stimuli, but modulated by these stimuli at levels comparable to the behavioural thresholds of pigeon reported by Kreithen and Quine (1979).