On the subdivision of static and dynamic fusimotor actions on the primary ending of the cat muscle spindle

1. Using large ramp and triangular stretches a survey has been made of the effect of stimulating single gamma fusimotor fibres on primary endings of muscle spindles in the peroneus brevis to see whether 'intermediate' types of fusimotor action could be recognized, falling between the well known static and dynamic types. 2. Responses were classified into six groups, as detailed on pp. 844-846, ranging from apparently 'pure' dynamic action (category I) to apparently 'pure' static action (category IV). Models for a putative mixed action were produced by combining the stimulation of a static and of a dynamic fibre to the same spindle. The clearest sign of static action was firing on the releasing phase of the stretch. The essential sign of dynamic action, which survived combination with the more dominant static action, was the low adaptive decay of firing with a time constant of about 0-5 sec that occurs on the plateau of the ramp stretch. 3. Out of 153 responses, each elicited from a primary ending on stimulation of a single fusimotor fibre, 67% were apparently 'pure' examples of dynamic and static action. The remaining 33% of responses were to some degree suggestive of an admixture, in various proportions, of static and dynamic actions. For only 18% of them was there firm indication of such admixture. 4. When a given fibre was tested on more than one ending then, with one exception out of thirty-six instances, its action always proved to be either predominantly static or predominantly dynamic. There was no special tendency for an axon with a mixed action on one spindle to have a similarly mixed action on other endings so that individual fusimotor fibres were best classified as static or dynamic without intermediate grades. 5. Simultaneous stimulation of two fusimotor fibres eliciting apparently 'pure static and dynamic actions, could mimic all the intermediate types of action. 6. The results are discussed in relation to recent studies, especially those based on glycogen depletion. It was concluded that dynamic action arises from activation of the bag1 intrafusal muscle fibre, and that static action arises from the bag2 and chain fibres, whether acting individually or collaboratively. The intermediate actions are suggested to arise from an overlap of motor innervation to contrasting types of intrafusal muscle fibre. 7. On the basis of effects on the regularity of the afferent discharge the findings support the view that a given static action axon can innervate bag2 and chain fibres in various proportions in different spindles, so that they do not provide separable effector pathways. 8. Responses to large amplitude sinusoidal stretching were also studied in relation to our classification.

Fast-conducting skeletofusimotor axons supplying intrafusal chain fibers in the cat peroneus tertius muscle

1. In six experiments on cat peroneus tertius muscle, from 12 to 23 motor axons with conduction velocities above 85 m/s were repetitively stimulated so as to produce glycogen depletion in the muscle fibers they innervated. 2. The whole muscle was then quick-frozen, serially cut, stained to demonstrate glycogen, and examined for intrafusal glycogen depletion. 3. Zones of glycogen depletion were found in 27 of the 99 examined spindles: they were almost invariably located on chain fibers and specifically on the longest of the chain fibers in affected spindles. 4. Since it was shown that there are no purely fusimotor fast axons in the motor supply to peroneus tertius, it is concluded that skeletofusimotor axons are present among the fastest motor axons to this muscle.

Frequency of tendon organ discharges elicited by the contraction of motor units in cat leg muscles

1. The responses elicited in individual tendon organs by the contraction of single motor units were studied in peroneus longus, peroneus brevis, tibialis anterior and soleus muscles. 2. No simple relation was found between the discharge frequency of a tendon organ and the tension produced in the muscle tendon by the contraction of individual motor units. 3. The sensitivity of a given tendon organ to contractile tension was not the same for each of the motor units which elicited its discharge. There was no correlation between the sensitivity of the receptor and the strength of the motor units. 4. Upon repetitive stimulation of a tendon-organ-activating motor unit at increasing rates, the frequency of the receptor sustained discharge reached a maximal value for rates of stimulation eliciting submaximal tetanic tension. Higher rates only produced an increase in the dynamic component of the tendon organ response. 5. These observations show that the contractile tension sensed by a tendon organ is not a simple fraction of the tension which appears at the muscle tendon. They might be accounted for as consequences of the fine structure of tendon organs and of variations in the number of muscle fibres contributed by different motor units to the bundle inserted on each receptor. The location of most tendon organs at musculo-aponeurotic junctions rather than in the tendon proper, could also be responsible for some of the observed discrepancies.

[Phosphorus requirements of bacteria metabolizing hydrocarbons in the sea]

The artificial stimulation of biological purification of sea-pollutant hydrocarbons requires phosphorus supply. The concentrations, corresponding to the optimal bacterial growth, depend, in particular on ionic strength. They range between 2 and 8 X 10(-4) M for waters in which the salinity is close to the mean salinity of an oceanic environment and between 1.5 and 3 X 10(-3) M when these waters receive a significant supply of freshwater or when salinity is naturally weak. Inhibition of bacterial development has been observed either with a microflora, or with pure strains for concentrations higher than the upper limits of concentrations so defined.

[Quantitative separation of biological lipids by successive chromatographic runs on juxtaposed thin layers (author's transl)]

During a study on incorporation of 14C-labeled precursors in biological lipids, we had to elaborate a method of quantitative separation of lipid classes, based upon three successive chromatographic runs on juxtaposed thin layers. The first thin layer, on which the lipid extract is applied, consists of silica gel alkalised by means of sodium hydroxide solution. The second thin layer is constituted only by silica gel G. The three one-dimensional migrations are respectively carried out in the following solvent systems: diethyl ether-hexane-benzene (55:30:15), hexane-benzene (80:20) and diethyl ether-benzene-acetic acid (62:20:18). The lipid fractions are scraped out and counted by liquid scintillation. The reproducibility of the whole operation is discussed.

Heterogeneity of motor units activating single Golgi tendon organs in cat leg muscles

The aim of this study was to investigate whether an individual Golgi tendon organ can signal the contraction of motor units with different physiological properties. The axonal conduction velocity and tetanic tension of motor units were examined in four muscles of the cat leg (peroneus brevis, peroneus longus, tibialis anterior and soleus). The motor units which were found to activate a given tendon organ had contractile properties dispersed over the same range as those of the whole muscle population. The proportion of tendon organ-activating motor units found in the studied samples suggests that altogether, the Golgi tendon organs of a muscle monitor the contraction of every motor unit in this muscle.

Cytochemical and electron-microscopic study of the paraoesophageal bodies and related nerves in Schizophyllum sabulosum (L.), Diplopoda Julidae

The ultrastructural study of the paraoesophageal bodies of Schizophyllum sabulosum reveals the occurrence of two axonal types (ax 1 and ax 2) near secretory cells. Two possibilities exist for the functional role of the nerves related to these paraoesophageal bodies. The results of treatment with proteases (pronase, pepsin, trypsin) and the identification of glycogen in both the paraoesophageal bodies and the nerves that link them to the brain and Gabe organs, suggest transport of at least part of the secretions from the paraoesophageal bodies to the Gabe organs.

Unsutured Dacron prosthesis in groin hernias

We have repaired difficult groin hernias during the past six years by an original procedure consisting of fitting an unsutured Dacron patch between the peritoneum and the muscular layers using a median lower abdominal incision. Our standard technic is described along with its variations and applications.

[The paracommissural regions (brain neurohemal formations) of diplopods. Preliminary note]

The paracommissural plates of Diplopods are neurohemal "organs" anatomically not individualized in bodies separate from the brain. They lie near the transverse commissure (tritocerebral commissure s.l.). They are composed of at least two distinct types of axon terminals, glial cells, tracheae and a neural lamella facing a blood sinus. The axons of paracommissural plates of originate in neurosecretory cells lying in the ganglions of the transverse commissure. The release of granules partly occurs by exocytosis.

[The concept of renal dysplasia. Apropos of 67 cases]

The aim of this study, based upon 130 nephrectomies in children, was to emphasise the importance of congenital lesions in comparison with inflammatory lesions. In the context of congenital abnormalities, the abundance of our material made it possible for us to review our anatomical findings in the context of clinical and radiological data. This had led us to propose an anatomical classification of renal dysplasias. Although overlap cases exist, this classification into four separate entities according to the nature and extent of the histological and topographical lesions is satisfactory by virtue of its clarity. It is an agreement with the most recent publications of authors interested in the vast problem of renal malformations.

[Discharge frequency of tendon organs evoked by the contraction of motor units in the cat]

Isolated contraction of several motor units can excite a single tendon organ. Although the rate of receptor discharge may be different for each motor unit, it is not related to the tension. During repetitive stimulation of a motor unit at increasing frequency the receptor discharge reaches a maximum at rates below fusion frequency for that motor unit.