A comparative histochemical and immunocytochemical study on the secretory material in the subcommissural organ of Rana temporaria L

The secretory material within the cells of the subcommissural organ (SCO) of Rana temporaria has been studied histochemically by application of a classical staining method and immunocytochemically by use of an antiserum (gift of Prof. Sterba, Leipzig) raised against bovine liquor fibre (LF) material, the LF being the secretory product of the SCO. The immunocytochemical method appears to be more specific and more sensitive than the histochemical staining method. The LF can also be visualized immunocytochemically; the fibre reacting equally positively from the SCO until the spinal cord's end. A significant positive linear correlation exists both between the amounts of histochemically and of immunocytochemically stained material and between their concentrations. The suitability of the immunocytochemical staining method for quantification of the secretory material within the cells of the SCO is discussed.     

Morphofunctional and histochemical characteristics of the hindlimb muscles of the Rana temporaria in ontogeny

Mixed muscles of adult frogs respond to the increase in external potassium and to Ach by polyphasic contracture which is due to asynchronous activity of various groups of muscle fibers (fast phasic, intermediate and tonic ones). In the developing in vivo hindlimb muscles, the predominance of phasic contractile response and relatively weak tonic one were noted. In contrast to definitive muscles, in which maximum potassium and acetylcholine contractures are identical, growing muscles produce weak contractile reaction to Ach. Ach sensitivity of the developing muscles (as revealed by the contracture) is lower than in the definitive ones. Histochemical (studies on the lipid content and the activity of succinate dehydrogenase) and morphometric (the ratio of muscle fibers of different types at different stages of development, comparison of their diameters, relative size of tonic bundle, etc.) studies indicate that the development of morphological substrate for tonic contractions (tonic and intermediate muscle fibers) takes place at a lower rate as compared to the development of the substrate for phasic contractions. However, histochemically tonic fibers may be revealed already at the stage of myotubes.     

The nerve fibres controlling the gonadotropic activity of the hypophysis of Rana temporaria

Summary In 27 adult female specimens of Rana temporaria, the total interruption of the nervous pathways to the median eminence and the hypophysis was performed, without disturbing the normal blood supply of the hypophysis. In eight cases this complete interruption persisted three months after operation. In these animals there occurred no seasonal development of the eggs, ovaries and oviducts. In the 19 other operated animals a varying degree of regeneration of the interrupted nerve fibres occurred. In these animals a varying number of ripe eggs was present, but in many of them there existed a significant difference between the weight of their ovaries compared with that of the ovaries of the control animals. In all control animals the seasonal development of the ovaries and oviducts was normal. From these and from previous experiments it could be concluded that the A. F. negative nerve fibres of the median eminence, not originating from the magnocellular neurosecretory preoptic nuclei, are responsible for the normal seasonal development of the ovaries and oviducts in Rana temporaria. It must be these nerve fibres that release gonadotropic releasing factors into the blood capillaries of the median eminence. The A. F. positive neurosecretory fibres, the portal circulation of the pars distalis and the pituicytes of the median eminence play only a secondary part during this period of control of the gonadotropic activity of the hypophysis.     

The hypothalamo-hypophyseal system of Rana temporaria under osmotic stimulation with special reference to the hypothalamo-median eminence-distal lobe axis

The secretory activity of the hypothalamo-hypophyseal system in the frog Rana temporaria under conditions of dehydration has been studied histologically using two parameters, the amount of stained neurosecretory material and the amount of neurosecretory material labelled by a radioactive precursor. The results are indicative of an increased secretory activity of the hypothalamo-neural lobe system as a result of water deprivation. In addition the involvement of the preoptic nucleus-median eminence axis in osmoregulation is confirmed. The pattern of distribution of autoradiographic silver grains over the median eminence together with data from literature support the idea that mesotocine is involved in the regulation of the activity of the adenohypophysis.     

On Sympathetic Innervation of Muscle Spindles of the Frog Rana temporaria

The work is concerned with solution of a questionable problem, whether there exists a direct sympathetic innervation of muscle spindles. On the isolated total preparations of muscle spindles, with the aid of a specific histochemical fluorescent method using glyoxylic acid, revealed is the sympathetic innervation of these structures: adrenergic terminal axons were found both on the intrafusal muscular fibers and the blood vessels supplying the receptor.     

MHC zygosity in the frog,Rana temporaria

The major histocompatibility complex (MHC) zygosity of the field-collected frogs, Rana temporaria, was detected by progeny testing. Groups of sibling tadpoles were grafted with intrafamilial tail-tip allografts and the ratio of rapidly rejected allografts to slowly rejected ones was estimated. Twenty-five percent of parental frogs appeared to be MHC homozygotes. Thus, MHC homozygosity in natural frog populations seems to be considerably higher than in wild mouse populations.     

Cyclical mitotic activity in the adeno-hypophysis of Rana temporaria

Summary In the pars distalis, the pars intermedia and the pars tuberalis of the hypophysis of Rana temporaria, an annual mitotic cycle is described.In the pars distalis there exists a gradient of mitotic activity, corresponding to a gradient of distribution of the PAS positive cells.In the pars distalis, the rate of cell degeneration and of cell renewal of the PAS positive cells seems to be faster than of the orange G positive cells.The replacement of degenerated PAS positive cells of the pars distalis seems to occur mainly during the months immediately following on the period of maximal activity of the PAS positive cells.     

Stretch receptors of the lungs in the frog Rana temporaria

In experiments on isolated lungs, studies have been made on the activity of single afferent fibers during simulated expiration and inspiration. Both slowly adapting and rapidly adapting voluminous stretch receptors were found in the frog lungs. The latter type exhibits the activity also during fast simulated expiration. Using acetylcholine and histamine, it was shown that the level of excitability of the receptors investigated depends on functional condition of the plain muscles in the pulmonary wall.     

Amino acids as olfactory stimuli in the Rana temporaria

Stimulation of the olfactory receptors in the frog by 10(-3) and 10(-4) M solutions of 22 amino acids results in generation of slow potential and evoked waves in the olfactory bulb. The amplitude, duration and area of the slow potential, as well as the frequency of onset of the induced waves served as an index of effectiveness of the amino acids. All the amino acids were shown to be the effective stimuli, the irreplaceable ones being more effective as compared with the replaceable amino acids. Among the former, basic amino acids (lysine, histidine, arginine) were most effective.     

Temperature and immobility reaction in Rana temporaria

Experiments were conducted on two groups of Rana temporaria acclimatized to 7°C and to 14°C. Two hours prior to the experiments the animals were divided into six groups of 40 subjects each and placed in containers at temperatures of 5°, 10°, 15°, 20°, 25° and 30°C. Frogs remained immobile for a shorter time in temperatures which differed little from those of acclimatization. It was concluded that the body temperature interferes with the duration of the immobility reaction.     

The hypothalamo-hypophysial system of the frog Rana temporaria

Summary The median eminence (ME) of the adult frog, Rana temporaria, was studied by means of electron microscopy including quantitative electron-microscopic autoradiography. In frogs captured in May and June numerous peptidergic neurosecretory fibres extending via the internal zone to the pars nervosa display large swellings containing few granules, mitochondria, neurotubules and cisternae of the smooth endoplasmic reticulum. In addition, few secretory globules up to 1.5 m in diameter occur in these varicosities. In animals collected during the autumn period many of these neurosecretory swellings filled with neurosecretory granules and polymorphic inclusions resemble Herring bodies. Three types of granule-containing neurosecretory fibres were observed in the external zone (EZ) of the ME of adult R. temporaria. Peptidergic A₁- and A₂-type fibres are characterized by granules 150–220 nm and 100–160 nm in diameter, respectively. Monoaminergic fibres of type B with granules approximately 100 nm in diameter represent 50% of all neurosecretory elements in the EZ of the frog ME; 12% of the total number of granule-bearing axons in the EZ actively taking up radiolabelled 5-hydroxytryptophan are thought to be serotoninergic terminals. Neurosecretory terminals of all types and glial vascular endfeet establish direct contacts with the perivascular space of the primary portal capillaries. Some neurosecretory terminals are separated from the lumen of the third ventricle by a thin cytoplasmic lamella of tanycytes. The possible physiological significance of this structural pattern is discussed.