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Notes: Summary Muscles of the lower legs of rats given 25% ethanol in water ad libitum for up to 9.5 months were studied using histological, histochemical and electrophysiological techniques. Ethyl alcohol was substituted for about 20% of the total calorific input of the animals. The observations were compared with the structure of the gastrocnemius muscle of five alcoholics with clinical neuropathy. Fibrillation potentials and angulated atrophic fibers were observed in the muscles of animals on alcohol for 9.5 months. No fiber type grouping was present. There was also phagocytosis of the muscle fibers and changes in their internal structure, as reflected by the distribution of NADH-diaphorase. The observed muscle changes in the alcoholics and those in the experimental animals on alcohol differed mainly quantitatively, the only exception being the presence of fiber type grouping in the biopsies from the alcoholics.

Notes: Abstract Circulating blood volume (BV) as the sum of circulating red cell volume (RCV) and plasma volume (PV) was estimated in rats native to a simulated altitude of 3500 m (“natives”), in rats born at sea level and later in life transferred to the simulated high altitude (“newcomers”), and in control sea-level rats. RCV per kg body weight (b.w.) was significantly larger in both “newcomers” and “natives” than in controls. PV per kg b.w. was in the “newcomers” insignificantly and in the “natives” significantly smaller than in the controls. BV per kg b.w. in both high altitude groups tended to be larger than in controls but the difference was not significant. Arterial haematocrit (Ahct) in the “newcomers” was significantly higher than in the controls, and in the “natives” significantly higher than in both other groups. Body haematocrit (the ratio of RCV and BV in per cent) was smaller than Ahct in all groups; this was more pronounced in the “newcomers” than in the controls and even more so in the “natives”. Apparently the haematocrit in the minute vessels of the organs of animals exposed to chronic hypoxic hypoxia increases much less than might be expected from changes of the Ahct. An attempt was made to evaluate the possible error of the more commonly used method of estimating BV, when only RCV, or only PV, is measured, and BV and its complementary fraction are calculated from arterial or venous haematocrit. When, in our results, BV was calculated from RCV and Ahct, the absolute values and also the differences between groups were somewhat underestimated. When BV was calculated from PV and Ahct, the BV itself, and particularly the differences between groups, were overestimated quite considerably. It is suggested that the only safe way to estimate BV is to measure RCV and PV separately.

Notes: Abstract The possibility that polyphloretin phosphate (PPP) antagonizes the central effects elicited by prostaglandin (PG) E2 and F2α was investigated. PPP was administered i.c.v. to male Wistar rats (10 or 25 μg) 10 or 30 min before i.c.v. injection of PGE2 or PGF2α (1 or 10 μg). The duration of several components of behavior, the degree of irritability, and the rectal temperature of rats were measured; the levels of noradrenaline, dopamine, 5-hydroxytryptamine, and 5-hydroxyindoleacetic acid were measured spectrophotofluorometrically in discrete brain areas. PPP antagonized temperature and behavioral changes induced in rats by PGF2α, but not those induced by PGE2. The magnitude of antagonism depended on the dose of PPP and on the time of the pretreatment before PGF2α administration. Changes in the level of biogenic amines in discrete brain areas evoked by PGs were not affected by PPP. We found that PPP antagonizes the central effects of PGF2α but not those of PGE2, and that changes of biogenic amines in discrete brain areas elicited by PGs are not specific.

Notes: Abstract Uptake of the nonmetabolizable model amino acid 2-aminoisobutyric acid (=AIB) through the basolateral membrane into epithelial cells was studied in sheep colon stripped of serosa and muscle layers. Only the antiluminal surface of the mucosa was exposed to the incubation medium. Thus AIB entry into epithelial cells could only occur through the basolateral membrane. AIB was taken up by a saturable process against a high concentration gradient. AIB uptake was inhibited by other neutral amino acids but not by sugars. In a low Na+ medium AIB uptake was impaired, indicating that active transport of amino acids through the basolateral membrane of colon epithelial cells is Na+-dependent. In the rat a saturable concentrative uptake of AIB through the basolateral membrane of colon epithelial cells has also been demonstrated. Concentrative uptake of amino acids through the basolateral membranes is probably important for the supply of colon epithelium with amino acids.

Notes: Abstract PAH secretion (TPAH) was studied in rats at spontaneously occurring glomerular filtration rate (GFR). At saturated transport, TPAH was found to be correlated to GFR. This relationship was also observed at unsaturated transport where TPAH depends upon the PAH concentration in arterial plasma. However, no significant correlation between TPAH and renal PAH load or renal plasma flow rate was found when the effects of GFR were removed by partial correlation analysis. A dependency of TPAH on GFR explains the correlations found between filtration fraction (FF) and renal PAH extraction (EPAH) or renal tubular PAH extraction fraction (EPAH-FFPAH). Thus, even at low PAH concentration in a. plasma, renal PAH extraction may only be assumed to be constant if the filtration fraction is constant.

Notes: Abstract Theoretical deductions have shown that a shift of the blood O2 dissociation curve (ODC) to the right might improve O2 transport to tissues at normoxia and at mild hypoxia whereas at severe hypoxia the organism should be better off with an ODC shifted to the left (Turek et al., 1973b; Turek and Kreuzer, 1976). The present study was performed in order to ascertain this ambiguous effect of an ODC shift depending on the degree of hypoxia in intact animals. A major displacement of the ODC to the left was achieved in rats by chronic administration of sodium cyanate (NaOCN). Control animals received sodium chloride (NaCl) instead. Arterial and mixed-venous $$P_{{\text{O}}_{\text{2}} }$$ , $$P_{{\text{CO}}_{\text{2}} }$$ , and pH were measured at normoxia and during breathing 14.9, 8.0, or 5.6% O2 in N2 in both groups. From $$P_{{\text{O}}_{\text{2}} }$$ , pH, ODC and arterial hematocrit, arterial and mixed-venous O2 contents were estimated and $$({\text{a}} - {\text{v)}}_{{\text{O}}_{\text{2}} }$$ as an index of blood O2 extraction was obtained. At normoxia and during breathing 14.9% O2 the NaOCN rats had a lower mixed-venous $$P_{{\text{O}}_{\text{2}} }$$ than the NaCl rats without any difference in pH. Arterio-venous O2 difference did not differ at normoxia but was lower in NaOCN rats at 14.9% O2. However, at 8.0 and 5.6% O2 the NaOCN rats had a higher mixed-venous $$P_{{\text{O}}_{\text{2}} }$$ , an increased $$({\text{a}} - {\text{v)}}_{{\text{O}}_{\text{2}} }$$ , and a higher pH (arterial and mixed-venous). At 5.6% O2 the NaCl rats developed a severe acidosis concomitant with pronounced hypocapnia. These findings confirm that rats with a left-shifted ODC have an impaired O2 transport to tissues at normoxia and mild hypoxia but a more efficient O2 transport at severe hypoxia as compared with rats with an unshifted ODC, in agreement with our previous theoretical studies.

Notes: Abstract A major displacement of the blood O2 dissociation curve (ODC) was achieved in rats by chronic administration of sodium cyanate (NaOCN). Control animals with a normal position of the ODC received NaCl instead. Arterial and mixed-venous O2 content ( $${\text{C}}_{{\text{O}}_{\text{2}} }$$ ) and O2 consumption were measured during breathing room air, 14.9, 8.0, or 5.6% O2 in N2. Cardiac output was obtained by the Fick principle.86RbCl was administered i.v., the rats were killed and the activity of86Rb in heart, spleen, stomach and intestines, liver, kidney, skeletal muscle, and skin was measured. According to Sapirstein (1956, 1958) the fractional uptake of86Rb in these organs corresponds to the fractions of cardiac output supplying these organs, and from the fractional uptake and cardiac output the nutritional blood flow may be calculated. Arterial and mixed-venous $${\text{C}}_{{\text{O}}_{\text{2}} }$$ was larger in the NaOCN than in the NaCl rats at all levels of oxygenation. At normoxia and 14.9% O2 the venous $${\text{C}}_{{\text{O}}_{\text{2}} }$$ was enlarged more than the arterial one, and so the arterio-venous O2 difference [ $$\left( {{\text{a}} - {\text{v}}} \right)_{{\text{O}}_{\text{2}} }$$ ] as an index of the O2 extraction in the body was smaller in the rats with a left-shifted ODC. However, at more severe hypoxia (8.0 and 5.6% O2) the arterial $${\text{C}}_{{\text{O}}_{\text{2}} }$$ in the NaOCN rats was enlarged more than the mixed-venous one, resulting in a larger $$\left( {{\text{a}} - {\text{v}}} \right)_{{\text{O}}_{\text{2}} }$$ (and therefore O2 extraction) when compared with the NaCl animals. Cardiac output was larger in the NaOCN than in the NaCl rats at 14.9 and 5.6% O2, when expressed per kg body weight. At 14.9% O2 the augmented cardiac output compensated for the lower O2 extraction when compared with the NaCl animals. At 5.6% O2 the NaOCN rats had both a larger ( $$\left( {{\text{a}} - {\text{v}}} \right)_{{\text{O}}_{\text{2}} }$$ ) and cardiac output than the NaCl animals. In the NaCl rats the decreased O2 extraction was not compensated for by an augmented cardiac output and therefore their O2 consumption was not only lower than that of the NaOCN rats but decreased even below the normoxic value of the NaCl rats. Coronary blood flow was increased in both NaOCN and NaCl animals at deep hypoxia to about the same extent, but due to a much lower arterial $${\text{C}}_{{\text{O}}_{\text{2}} }$$ of the NaCl animals, their O2 supply to the heart was lower than that of the NaOCN rats. The nutritional blood flow to spleen, kidney, liver, stomach and intestines, and skin in ml/min · g was lower in the rats with a normal position of the ODC than in those with a left-shifted ODC. This, together with the low arterial $${\text{C}}_{{\text{O}}_{\text{2}} }$$ of the NaCl rats, suggests a serious compromising of the O2 supply to these organs. Results of this study support the conclusion of our theoretical studies (Turek et al., 1973; Turek and Kreuzer, 1976) that a shift of the ODC to the left might be disadvantageous for the O2 transport to tissues at mild hypoxia, but advantageous at severe hypoxia.

Notes: Abstract In rats with a myocardial infarction due to ligation of the left coronary artery a marked right ventricular hypertrophy developed after 41/2 weeks. At this time no difference against control animals was observed in arterial $$P_{{\text{O}}_2 }$$ , $$P_{{\text{CO}}_2 }$$ , pH, ideal alveolar $$P_{{\text{O}}_2 }$$ , and alveolar-arterial O2 pressure difference, as measured in unanesthetized animals at normoxia. In histological sections of the heart stained by PAS reaction capillaries and muscle fibers were counted, and the mean intercapillary distance and muscle fiber diameter were estimated. In the right ventricle of the rats with myocardial infarction both increased when compared with control animals or with sham-operated rats. Fibercapillary ratio was the same in all three groups. Similar results were obtained in the remaining undamaged tissue of the left ventricle of rats with a myocardial infarction when compared with the left ventricle of control or sham-operated rats. Findings concerning intercapillary distance suggest that also in the myocardium which remains intact during the development of the infarction and later hypertrophies, tissue oxygen transport might be impaired, particularly during a stress situation. Results in the right ventricle of rats with myocardial infarction show an opposite trend against rats exposed chronically to simulated high altitude, where in the hypertrophied right ventricle a shorter intercapillary distance occurs and therefore an improvement of tissue oxygen transport might be expected.

Notes: Summary The effect of the phosphodiesterase inhibitor 4-(3-cyclopentyloxy-4-methoxyphenyl)-2-pyrrolidone (ZK 62711) on gastric secretion and the cyclic AMP system of the gastric mucosa was studied in rats and guinea pigs. In rats, 0.03–0.3 μmoles/kg ZK 62711 i.v. stimulated acid and pepsin secretion in a dose-dependent manner and 0.03 μmoles/kg i.v. enhanced the effect of histamine. In guinea pigs no reproducible stimulation was found after intravenous injections of ZK 62711. The stimulation of gastric secretion in the rat by 0.3 μmoles/kg ZK 62711 i.v. was not affected by vagotomy but was totally inhibited by 10 μmoles/kg cimetidine i.v. The structurally related phosphodiesterase inhibitor, 4-(3-butoxy-4-methoxybenzyl)-2-imidazolidine (Ro 20-1724), at the dose of 3.3 μmoles/kg i.v. stimulated gastric secretion in anaesthetised rats to a similar extent as 0.3 μmoles/kg ZK 62711 i.v. The content of cyclic AMP in the rat gastric mucosa in vivo was slightly increased by 10 μmoles/kg ZK 62711 i.v, whereas lower doses did not change it. Accumulation of cyclic AMP in the rat gastric mucosa by 50 μmoles/kg histamine i.v. was enhanced by simultaneous injections of 3.3 μmoles/kg ZK 62711 i.v. In rat gastric tissue slices in vitro 1–50 μM ZK 62711 increased the level of cyclic AMP but 100 μM histamine had no effect in the absence or presence of ZK 62711. In gastric mucosal slices of the guinea pig 10 and 50 μM ZK 62711 increased the cyclic AMP content which effect was inhibited by 100 μM cimetidine and enhanced the stimulatory effect of 100 μM histamine on cyclic AMP. The activity of soluble cyclic AMP phosphodiesterase was inhibited by ZK 62711 in the rat (IC50=18 μM) and guinea pig gastric mucosa (IC50=1.5 μM). Adenylate cyclase was not affected in the homogenate of the guinea pig gastric mucosa. The results indicate that the phosphodiesterase inhibitor ZK 62711 which increases cyclic AMP levels in the gastric mucosa in vivo and in vitro, is a potent stimulator of gastric acid secretion.

Notes: Summary The presence and distribution of myocardial α-adrenoceptors in different parts of the heart of various mammalian species was investigated. For this reason experiments were performed in isolated cardiac preparations of rats, guinea pigs and cats. In order to obtain more information about the nature of the cardiac α-adrenoceptors additional experiments were undertaken at different temperatures. These studies were aimed to show whether or not a conversion of β-to α-adrenoceptors or vice versa takes place. Moreover, we analyzed the influence of hypothyroidism on the sensitivity of α- and β-adrenoceptors of preparations from rats fed with propylthiouracil. Finally, we tried to find out whether stimulation of these α-adrenoceptors leads to the formation of the cyclic nucleotides cAMP and cGMP. The following results were obtained: 1. In right ventricular strips of rats, guinea pigs and cats phenylephrine stimulated α-adrenoceptors. After blockade of β-adrenoceptors the respective pD2-values of phenylephrine were 5.32, 5.99 and 5.33. The doseresponse curves obtained in the presence of α-adrenolytic drugs were shifted to the right without depression of the maximum. In the rat, in addition, the pA2-values for the α-adrenolytic drugs yohimbine (5.79) and phentolamine (7.85) were determined. They were at least 0.5 log units higher than those found in the rat for other α-adrenoceptors (Van Rossum, 1965) thus supporting the view that the population of cardiac α-adrenoceptors is different from that of other organs. In left ventricular strips of guinea pigs the pD2-value for the α-mimetic effect of phenylephrine was of the same order of magnitude as that obtained in the right ventricle. 2. In the papillary muscle of the right ventricle of guinea pigs and cats phenylephrine stimulated α-adrenoceptors. 3. In the left atrium of the rat, phenylephrine stimulated myocardial α-adrenoceptors (pD2: 5.58). Also in this preparation the pA2-values for yohimbine (6.36) and phentolamine (8.21) were different from those found for other α-adrenoceptors in the rat (Van Rossum, 1965). Likewise in strips from the left atrium of the cat myocardial α-adrenoceptors are present. 4. In spontaneously beating right atria of the rat a clear-cut positive chronotropic effect mediated by stimulation of α-adrenoceptors could not be demonstrated although in 6 out of 15 preparations a small positive chronotropic effect became evident. No positive chronotropic effect at all was obtained by stimulation of α-adrenoceptors in the cat right atrium. 5. In ventricular strips as well as in left atria from hypothyroid rats the pD2-value for the α-effect of phenylephrine was increased, in the atrium more than in the ventricle, while the pA2-values for yohimbine and phentolamine were not significantly different from the controls. Under these conditions a distinct positive chronotropic effect mediated by stimulation of α-receptors was found in the spontaneously beating rat atrium. 6. After stimulation of α-adrenoceptors in atria and ventricular strips of normal and propylthiouraciltreated rats, as well as in strips of guinea-pig ventricles or cat atria no elevation of cAMP and cGMP was observed. 7. The concept of a single adrenoceptor convertible from α- to β-type or vice versa was not supported by our experiments. These were carried out at different temperatures on left atria and on ventricular strips of rat hearts using the irreversible α-adrenoceptor blocking agent phenoxybenzamine. 8. The present experiments provide evidence for the existence of α-adrenoceptors in the myocardium of various mammalian species. Their stimulation produces positive inotropic effects without increases in heart rate.

Notes: Summary The effects of the inhibitor of the tyrosine-hydroxylase H 44/68 and the inhibitor of the dopamine-β-hydroxylase FLA 63 on the diurnal variations of the motor activity was studied in male Wistar rats, which were kept under standardized conditions of light and darkness (L:D=12:12h). The motor activity was continuously registered in groups of 5 rats using a two-channel Animex motimeter. During light FLA 63 (40 mg/kg, s.c.) greatly increased motor activity on acute application and during darkness the physiological elevation in motor activity was further but slightly increased. H 44/68 (200 mg/kg, i.p.) also increased motor activity during light, but in contrast to FLA 63 greatly reduced motor activity during darkness. The results indicate that though dopamine and noradrenaline are involved in the regulation of behavioural components, one or the other catecholamine may play a predominant role at different times of the day. Thus, it seems worthwhile to study the effects of drugs separately during light and during darkness.

Notes: Summary The interaction of cortico- and nigrofugal inputs to the striatum of the rat was investigated using the technique of evoked potentials. Repetitive, unilateral stimulation of the substantia nigra inhibited potentials which were evoked from the ipsilateral rostral cortex and recorded from the ipsilateral striatum. The inhibition was antagonized by low doses of various intraperitoneally administered neuroleptics such as: pimozide (0.1–0.2 mg/kg), haloperidol (0.1–0.5 mg/kg), chlorpromazine (0.5–2.0 mg/kg) and thioridazine azine (0.5–4.0 mg/kg). These findings are discussed in view of the existing controversy regarding the mode of action of dopamine in the striatum.

Notes: Summary Under controlled conditions of environmental light and darkness of 12:12 h the turnover of dopamine and noradrenaline in brain of male Wistar rats was studied at different times of the day. The turnover was calculated from the decline of the amine concentrations either after inhibition of the tyrosine-hydroxylase with H 44/68 (200 mg/kg, i.p.) or after inhibition of the dopamine-β-hydroxylase with FLA 63 (40 mg/kg s.c.). Whereas the noradrenaline turnover showed only slight but not significant variations within 24 h, the turnover of the central dopamine exhibited significant variations with increased turnover rates in the second half of the light and first half of the dark period. Thus, diurnal variations have to be taken into account when studying the effects of drugs on the turnover of biogenic amines in the central nervous system.

Notes: Zusammenfassung Perhexilin (Pexid®) verursacht bei der Ratte das generalisierte Auftreten von lamellären und kristalloiden zytoplasmatischen Einschlußkörpern, die denjenigen gleichen, die bei Patienten mit Perhexilin-induzierter Polyneuropathie beschrieben worden sind. Aus den vorgelegten Befunden wird geschlossen, daß Perhexilin, eine amphiphile kationische Verbindung, ein starker Induktor einer generalisierten Lipidose ist.

Notes: Summary DNA repair time-course was studied after injury by N-methyl-N-nitrosourea (MNU) in rat liver cells of animals of different ages and in fetuses using hydroxyurea (HU) as inhibitor of scheduled DNA synthesis. DNA repair was a rapid phenomenon, more so in young adults than in newborns, and was not detectable in fetuses. A correlation seems to exist among organ sensitivity to carcinogen, age of animal and DNA repair.

Notes: Summary Sixteen 58-day-old male rats of Wistar strain, with a mean body weight of 179 g, were divided into two equal groups. Each group of eight animals was maintained for 70 days on drinking water, ad lib., containing no fluorine (control group) and 100 ppm of fluorine (experimental group). All specimens examined were obtained from the incisal portions of the incisors. The following types of enamel specimens were prepared for scanning electron microscopy: (1) acid-etched specimens; (2) acid-etched specimens followed by low temperature microincineration; and (3) fractured specimens. The enamel formed during high fluoride exposure showed marked hypocalcification, that is, the crystallite density in the prism core and interprismatic region was lower than that of control animals. The organic substances appeared to increase in these regions. These changes were prominent in the outer and middle enamel layers. Such changes following fluoride administration appear to indicate an inhibition of enamel maturation, that is, an inhibition of the mineral deposition and/or an inhibition of organic matrix withdrawal.

Notes: Summary The ileal epithelial cells containing the tubulo-vacuolar systems and supranuclear vacuoles in suckling rats were investigated with scanning electron microscopy, using specimens treated with osmium-thiocarbohydrazide-osmium staining methods, and critical point drying and cracking. The cracked surface of the apical cytoplasm is seen as irregular and small hollows and pores of the anastomosing and branching tubulo-vacuolar system. The cracked surface of the supranuclear vacuoles shows the ellipsoidal structures. Numerous pores of various size and irregular shape are present on the apical inner surface of the supranuclear vacuole. These pores are clearly the openings from the tubulo-vacuolar system to the supranuclear vacuole. Some small pores are visible on the inner lateral surface of the supranuclear vacuole, especially near the nucleus. They are probably the pathways of the absorbed materials from the supranuclear vacuole into the lateral cytoplasm. Usually, the inclusions of the supranuclear vacuole reveal the globes or coarse and sponge-like networks.

Notes: Summary In the “clean” rat skin purified from the panniculus carnosus the oxygen consumption of the spontaneous and artificially induced skincycle was measured at different times of day. The level of oxygen consumption correlated to diurnal and nocturnal periods. During the skincycle the oxygen consumption showed fluctuations. There were indications that the value of oxygen consumption of the early anagen is influenced by that phase of the cycle at which the new cycle is artificially induced. Furthermore, it was found that a certain decrease of oxygen consumption stimulates the quiescent hair follicles to spontaneous proliferation. During the katagen the peak value of the oxygen consumption seemed to be correlated with specially morphofunctional perifollicular changes. The application of these findings to the pathophysiology of human hair growth disturbances is discussed.

Notes: Summary During different embryonic and postnatal stages, 6-aminonicotinamide (6-AN) was administered to Wistar albino rats. The capillarization of the occipital cortex has been examined morphometrically. A 6-AN-vulnerable stage of prenatal development was found, which lasted to the 19th prenatal day and which only partly corresponds to the so-called ‘critical stage’ of capillary sprouting (Kapillarsprossung). Capillary sprouting was not impaired by 6-AN during postnatal stages. Impairment of capillarization by 6-AN might be the result of glial lesion. The importance of glia for capillarization is discussed.

Notes: Summary Glyoxylic acid-induced fluorescence technique and a copper thiocholine method were used to investigate the ontogenesis of the catecholamine-containing and cholinesterase-positive nerves of the rat iris and cornea. First fluorescent nerve fibres appeared in the iris on the 18th gestation day and in the cornea on the 19th day. A rapid increase in the density of the adrenergic nerve fibres of the iris continued to the age of three weeks, while the number of such fibres were small in the cornea. Acetylcholinesterase-positive fibres appeared both in the cornea and in the iris on the 19th gestation day. Their density increased more rapidly in the iris, especially in the sphincter muscle, than in the cornea. Non-specific cholinesterase activity was localized in the Schwann cells and the reaction was more intense during development than in the nerves of the cornea of adult rats.

Notes: Summary The pre- and early postnatal development of serotonin neurons in the rat brainstem was studied using the fluorescence histochemical method. The technique utilized does not require drug pretreatment to visualize an intense serotonin fluorophore localized in neuronal perikarya, dendrites, and axons. All the serotonin neuron groups develop as bilateral nuclei which extend from the midbrain through the medulla. Six of the nine groups undergo a midline fusion from embryonic day 18 (E 18) through postnatal day 6 (P 6) in a rostrocaudal gradient. Cells of the nucleus raphe dorsalis fuse first (by P1), whereas the serotonin neurons located in nucleus raphe pallidus do not fuse until P 6. This gradient is comparable to the one described for the first observable fluorescence in the serotonin neurons groups. After final cell division, the serotonin neurons undergo a primary migration from the ventricular zone along the midline, where they are situated during embryogenesis, and a secondary migration extending into postnatal life which concludes with fusion in the midline. The bilateral origins of the serotonin cell groups are maintained in the adult. This is expressed by the apparent ipsilateral projections of some of the raphe neurons determined recently in our laboratory utilizing autoradiographic and horseradish peroxidase techniques.

Notes: Summary The basic cellular lesion in CNS of suckling rats treated with Pexid was studied by light and electron microscopy. The most pronounced abnormality, the formation of various intracytoplasmic inclusions, was found in neurons, astrocytes, oligodendrocytes, ependymal cells, endothelial cells and fibroblasts. These abnormal inclusions were generally membrane-bound, although clearly non-membrane-bound inclusions were occasionally found. The several internal patterns of the inclusions were (1) lamellar, both concentric and parallel, (2) reticular and (3) crystalloid. These alterations were completely resersed following withdrawal of the drug. The structural characteristics of the abnormal inclusions in Pexid-treated animals were similar to those found with certain hypocholesterolemic, neuroleptic, anorectic, and antimalarial drugs. This suggests that the inclusions occurring within the cells of animals treated with any of these drugs may develop in a similar manner, and that the formation of such inclusions is likely to be a form of cellular reaction common to certain metabolic disturbances.

Notes: Summary Within the retinal nerve fiber layer of a 6-week-old Sprague-Dawley rat, scattered aggregates of PNS myelinated axons have been found and described. We believe this is likely to represent a normal but rare phenomenon in the rat.

Notes: Abstract A manual system of various estimations of rat plasma alkaline phosphatase activity has been devised for small volumes of plasma which uses different inhibitors, compares the utilisation of two substrates and includes acrylamide gel electrophoresis. The different inhibitors etc. allow a degree of discrimination between alkaline phosphatase extracts of rat organs. The properties of isoenzymes, e.g. intestinal alkaline phosphatase, differ depending upon the environment in which they are studied. In conjunction, if necessary, with the methods described for the estimation of liver and intestinal alkaline phosphatase activity, it is hoped to use the system to discriminate between the isoenzymes present in the plasma alkaline phosphatase of rats in toxicological studies.

Notes: Abstract A modification of the distention ulcer was studied in albino rats and a new possibility of testing ulcerogenic side effects of drugs was described. The distention alone was not sufficient to produce lesions. The severity of ulcer lesions was highly dependent on the volume of the acid solution. Large volumes of 0.1 N HCl evoked severe ulcers within 1 h. Small amounts of weak acid solution did not cause any ulceration. Anti-inflammatory drugs administered in therapeutic doses, which did not yet produce any ulcers in animals, increased the sensitivity of the gastric mucosa against the aggresive factor, the acid. In animals pretreated by anti-inflammatory drugs in toxic doses an earlier development of ulceration was observed by distention with acid. Stress also accelerated and aggravated the formation of distention ulcers.

Notes: Abstract The effect of acute and chronic cadmium administration on hepatic drug metabolism was investigated in the male rat. 3 days after the acute administration of cadmium by either the intraperitoneal (0.84 mg Cd/kg) or the oral (〉 80 mg Cd/kg) route, there was a significant potentiation in duration of hexobarbital hypnosis and inhibition of hepatic microsomal metabolism of hexobarbital and aniline. Administration of cadmium in the drinking water at levels of 100 or 200 ppm Cd for periods of 2–12 weeks or at levels of 5 or 20 ppm Cd for 50 weeks did not produce alterations in either drug response or hepatic drug metabolism. Significant levels of metallothionein, a cadmium binding protein, found in the liver of the rats receiving cadmium chronically may offer an explanation for the observed differences in drug metabolism between the acute and chronic administration of cadmium. In additional studies, pretreatment of the rats with subthreshold doses of cadmium (0.21 or 0.42 mg Cd/kg) intraperitoneally produced a tolerance to the alterations in drug metabolism induced by the previous cadmium dose (0.84 mg Cd/kg, i.p.). However, chronic cadmium treatment (5 or 20 ppm Cd for 50 weeks) did not impart any such tolerance to subsequently administered Cd (0.84 mg/kg) by the intraperitoneal route. The hepatic levels of metallothionein induced by the chronic cadmium treatment were only 30–60% of those induced by the subthreshold cadmium and thus may not have bound enough of the large challenge cadmium dose to produce the tolerance phenomenon.

Notes: Abstract This report describes the application of a test system which applies different substrates, inhibitors and acrylamide electrophoresis to the study of the alkaline phosphatase activity of rats. The system, which was specifically devised to characterise the alkaline phosphatase activity of small quantities of plasma from rats in toxicological studies, was also used to examine the plasma from rats under several physiological conditions, e.g. time of day, age, diet, etc. These physiological factors can influence the measurement of plasma alkaline phosphatase activity and should be taken into account when designing toxicological studies. Different experimental regimes were used to produce increases in liver, bone and intestinal alkaline phosphatase isoenzymes in the plasma of rats and these were reflected in the characterisations by the system. Although much remains unknown, a few concepts of rat plasma alkaline phosphatase activity emerged under our conditions. There is a ‘tidal’ intestinal component which arises from feeding and is approximately 60% of the total activity of the fed rat. In the fasted rat this ‘tidal’ component has largely disappeared and the ‘core’ activity which remains is composed of approximately equal proportions of bone isoenzyme and another as yet ill-defined component. The liver isoenzyme which appears in the plasma of the cholestatic rat appears to be either a very minor component or absent from the plasma of our normal CFE derived rat.

Notes: Abstract In connection with a programme of investigations concerning the disposition of thallium in the rat and the influence of diuretic agents on the rate of elimination of thallium from the body, Tl2SO4 (48.9 μmol = 10 mg/kg) was given by mouth to conscious rats. Blood levels were studied as a function of time. They could not be described adequately by means of a classical Bateman function. The maximum blood level was achieved approximately 1 h following oral ingestion. Treatment with furosemide for 11 days (30 mg/kg twice daily) significantly accelerated the removal of thallium from the body with the urine. Approximately 35% of the administered thallium was excreted within one week following the injection of this diuretic agent. The excretion of sodium and water was also considerably enhanced, that of potassium hardly changed. Thallium itself displayed weak diuretic activity. Upon prolonged treatment (1–2 weeks) with furosemide the elimination of thallium, water and Na+ was still accelerated, although that of potassium proved diminished with respect to controls. Ethacrynic acid when administered repeatedly in appropriate doses caused retroperitoneal fibrosis. Therefore, this potent diuretic agent was not included in the investigations. Acetazolamide (30 mg/kg) also enhanced the excretion of thallium, especially within the initial 24 h of treatment. The effect was less pronounced than that of furosemide and rapidly exhausted. The results suggest that furosemide in a high dose is effective in accelerating thallium elimination from the body in the present animal model. Acetazolamide is probably not suitable for this purpose.

Notes: Summary Brain tumors were induced in Sprague-Dawley and Long-Evans rats by administration of N-methyl-N-nitrosourea in the drinking water. Of these tumors, a grade 2 mixed glioma, a grade 2 to 3 astrocytoma and a grade 1 to 2 oligodendroglioma were established in vitro, maintained in culture and designated 75SD-G-376, 75SD-G-420 and 77LE-G-180, respectively. Of these mass cultures, two were successfully cloned and are currently available as 75SD-G-376C and 75SD-420C cell lines. Clonal lines produce S-100 protein and grow as tumors when isografted in young rats. Using the cultured cells as target cells, specific antibodies were searched for in the sera of the rats with the primary tumors by means of an indirect fluorescent antibody staining method and a complement-dependent antibody-mediated microcytotoxicity assay. Fluorescent and cytotoxic antibodies were demonstrated in the sera of the mixed glioma- and astrocytoma-bearing animals. However, a variable proportion of cells of the 75SD-G-376 and 75SD-G-420 lines showed no reaction with the corresponding sera. Furthermore, cytotoxic anfibodies had a lytic effect on the autologous glioma cells only in the presence of rabbit complement.

Notes: Summary Pregnant rats received a single administration of 0.5, 1.0, or 2.0 mg/kg of cadmium on day 18 or 20 or gestation Maternal animals were killed on day 21 and samples of the caudate nucleus from fetal brains were examined using the transmission electron microscope. A 2.0 mg/kg dose of cadmium administered to maternal rats on day 20 of gestation caused the formation of vacuoles in the endothelial cells of capilaries in the fetal brain. Significant endothelial cell vacuolization was not observed in the brain of fetuses from other treatment groups. The vacuoles occurred singly, were spherical in shape, were located adjacent to the intercellular junctions and caused focal distortion of the endothelial cell. Vacuoles were the only ultrastructural alteration observed in the caudate nucleus of fetal brains.

Notes: Zusammenfassung Mittels des radioaktiv markierten Antagonist-Liganden (3H) (−) Dihydroalprenolol (DHAP) wurden spezifische Bindungsstellen in Membran-PrÄparationen von Erythrozyten der Ratte identifiziert, die aus folgenden Gründen alsΒ-adrenerge Rezeptoren angesprochen werden können: Im Gegensatz zur unspezifischen Bindung von DHAP war die spezifische Bindung abhÄngig von der Inkubationszeit und der Temperatur. Sie folgte einer SÄttigungskinetik, war — in AbhÄngigkeit von der Temperatur — reversibel und wies eine hohe AffinitÄt auf (KD für DHAP = 6,51 nM). Die rezeptorspezifische Bindung von DHAP wurde durchΒ-Rezeptorenblocker (Pindolol 〉 Alprenolol ≧ Propranolol 〉 Practolol) oderΒ-Sympathomimetika (Isoprenalin 〉 Adrenalin) kompetitiv gehemmt. Die (−) Enantiomeren von Pindolol und Isoprenalin hatten eine wesentlich höhere AffinitÄt als die antsprechenden (+) Enantiomeren. Die Dichte Β-adrenerger Rezeptoren (pmole/mg Eiwei\) nahm mit steigendem Retikulozytosegrad zu: Sie stieg auf das 4-bis 5fache an, wenn die Retikulozytenwerte durch Vorbehandlung der Tiere mit Azetylphenylhydrazin von 3 auf 80 % gesteigert wurden.

Notes: Summary The current investigation comprised normal young rats as well as rats submitted to a 50% food reduction or severe protein restriction. Isolated nerve fibres from lumbar spinal roots and sciatic nerves were investigated with reference to the relation between length and diameter of internodes as well as variation of internodal length along single nerve fibres. The present results do not support the view that protein-calorie malnutrition should cause neuropathy. Internodal segments were, on an average, shorter in relation to their thickness in young rats submitted to severe protein restriction or a 50% food reduction. The deviation was most marked in low-protein animals and particularly among coarser internodal segments. An inhibition of longitudinal growth was considered to be the main factor behind the difference between malnourished and normal rats.

Notes: Summary Male albino rats were anaesthetized with diazepam, injected with horseradish peroxidase and Evans blue-labeled albumin and given an embolus of 0.01 ml air in the right common carotid artery after ligation of the external carotid branch. The pial arteries of the right cerebral hemisphere were stained blue, particularly the middle cerebral artery and its main arterial branchlets. Ultrastructurally, some endothelial cells in the right middle cerebral artery, small arteries and arterioles showed a diffuse distribution of horseradish peroxidase in their cytoplasm, although these vessels only occasionally showed peroxidase in their basement membranes. Other endothelial cells in these arterial branchlets showed few if any signs of a diffuse distribution of peroxidase but displayed several pinocytotic vesicles and occasionally trans-endothelial channels filled with peroxidase, sometimes with a slight leakage of peroxidase into adjacent basement membranes and neuropil. Scattered pinocytotic vesicles were observed in capillaries and venules, but there was usually no extravasation of peroxidase around these vessels.

Notes: Abstract Adult male rats were subjected to 1–4 cycles of daily gastric intubation with ethanol (6 g/kg) for 16 days, separated by 17-day alcohol-free periods. Tolerance produced by this treatment (designated ‘physiological tolerance’) was measured by change in effect of a 2.2 g/kg i.p. dose of ethanol on the moving-belt test. It occurred in each cycle, disappeared completely in the drug-free periods, and developed more rapidly in the second and later cycles than in the first. Tolerance produced by the ‘behavioral augmentation’ technique (daily test practice under the influence of ethanol) also developed more rapidly on a second than on a first cycle. The progression from within-session to between-session tolerance was still evident, but accelerated. With 25-day alcohol cycles, separated by a one-month drug-free period, the ‘carry-over’ effect (i.e., more rapid acquisition of tolerance in the second cycle) applied equally, regardless of whether or not tolerance was produced by the same technique in both cycles, or by a crossover in either direction between the two techniques.

Notes: Abstract Rats were reinforced with water on a continuous reinforcement schedule and were also punished with electric shock for every fifth response applied to a silent, isometric, force-sensing manipulandum. Oral doses of chlordiazepoxide (3.0, 9.0, 27.0 mg/kg) increased both conventional rate and force of punished responding. In contrast, d-amphetamine (0.8, 1.6, 3.2 mg/kg, by gavage) further decreased conventional rate and force of response, but this latter drug increased the rate of recorded responses that were lower than the 15-g force criterion for response consequences. The results for chlordiazepoxide are viewed in terms of its anxiolytic properties, while the d-amphetamine data appear to support a theory of amphetamine effects based on the concept of stereotyped behaviors.

Notes: Abstract The release of proteins, sucrase (SA), maltase (MA), leucine aminopeptidase (LA) and alkaline phosphatase (AP) activity from rat jejunum by sodium deoxycholate (DOC) was studied by an in vivo perfusion technique. In our experimental conditions, a 2 mmol/l DOC perfusion for 30 min induced a marked and reversible release of proteins and hydrolases. When specific activities were considered, each enzyme showed a distinct release pattern. Significantly, the SA release was largely increased, the AP release was decreased and there was no correlation between the releases of SA and AP. Furthermore, the various enzymes recovered into the lumen were solubilized at different extents. SA was chiefly present in a soluble and AP in a particular form. The microscopical appearances showed a slight exfoliation of the epithelial cells from the villous tips but no specific changes when compared to the control group. The results are discussed in terms of enzymic localization in the brush border membrane; SA would be located very superficially in the surface membrane and AP buried in the membrane and less accessible than the other enzymes.

Notes: Abstract In vivo experiments were performed in male Wistar rats to elucidate the probable relation between renal concentrating ability and medullary cyclic AMP content as influenced by changes of hydration and by administration of antidiuretic hormone (ADH). Cyclic AMP levels were 37% lower in water diuretic than in control animals (P〈0.01), but were not significantly changed during prolonged antidiuresis induced by dehydration or ADH administration. Nor could any change of cyclic AMP levels be demonstrated between 2 and 20 min after ADH injection. Significant increases of medullary cyclic AMP content occurred following stress, anesthesia, and administration of isoproterenol and 3-isobutyl-1-methylxanthin. The results suggest that the level of cyclic AMP in the renal medulla may not be an important determinant of the antidiuretic response produced by ADH in rats.

Notes: Summary The epithelial surface of the Plica vocalis in adult male rat is studied by scanning electron microscopy. It's structure is compared with that of the plica and of the recessus ventricularis. The transition of the epithelium in the plica vocalis to the epithelium of the joining parts of the larynx is documented. Special attention is paid to the occurrence of microridges at the apical poles of epithelial cells in the larynx. Up to now microridge cells have been said to be characteristic for the plica vocalis.

Notes: Summary In the small segmental tail muscles of the rat beta fibres provide exclusively the dynamic fusimotor control, while gamma fibres provide exclusively the static fusimor control. The present experiments were made to investigate the fusimotor innervation of spindles in a large muscle of the rat, the soleus, and thus to determine the occurrence and significance of beta innervation in this muscle. Our results have revealed no case of beta innervation in the rat soleus. As a consequence of our experimental method, however, we would not claim that beta innervation does not exist in the soleus, only that it must play an insignificant role relative to that seen in the tail segmental muscles. Investigations of the fusimotor innervation of eight spindles were sufficiently complete to warrant detailed illustration. The number of gamma fibres ranged from two to four. In every case the slowest conducting gamma fibre was dynamic. However, the conduction velocity spectra for the static and dynamic gamma fibres to rat soleus overlap to such an extent that it is impossible to use conduction velocity as the sole guide to functional gamma fibre classification. The pooled results from the eight spindles fully investigated provide a ratio of static to dynamic gamma fibres of approximately 1:1. Other evidence discussed in the paper suggests that in the muscle nerve the ratio is considerably higher. These differences are reconciled if the dynamic gamma fibres branch more profusely and innervate more spindles than do the static gamma fibres.

Notes: Summary Place units in the dorsal hippocampus of the freely-moving rat signal the animal's position in an environment (place field). In the present experiments, thirty four place units were recorded in two different environments: one, a small platform where the rat had received neither training nor reward; the other, an elevated T-maze inside a set of black curtains where the rat had been trained on a place discrimination. The places within the curtained enclosure were specified by four cues (a light, a card, a fan, and a buzzer) in addition to the food. Other cues were eliminated by rotating the maze and the four controlled cues relative to the external world from trial-to-trial. Some units had place fields in both environments while others only had a place field in one. No relationship could be seen between the place fields of units with fields in both environments. All twelve units tested extensively in the controlled enclosure had place fields related to the controlled cues. Probe experiments in which only some of the controlled cues were available showed that some of these units were being excited by one or two cues while others were influenced in a more complex way. The fields of these latter units were maintained by any two of the 4 cues and were due to inhibitory influences which suppressed the unit firing over the rest of the maze.

Notes: Summary The effects of electrical stimulation of the lateral hypothalamus (LH) of rats on intraspecific aggressive behaviour were studied. In order to investigate the specificity of the stimulation effects, each experimental animal was stimulated in a number of different social situations. Stimulation of the LH in the presence of a subordinate male increased the amount of time spent on aggressive behaviour patterns and locomotion. In the presence of a dominant male, however, the stimulated animal never initiated a fight, whereas in the presence of an estrous female attack occurred in some rare occasions and sexual behaviour disappeared almost entirely. Stimulation of some sites also elicited mouse killing behaviour. Many of the electrodes that elicited intraspecific aggressive behaviour also supported intracranial self-stimulation. It is concluded that 1. electrical stimulation of this area of the LH predominantly potentiates intraspecific aggressive behaviour, 2. that this behaviour becomes overt depends on the external situation, including the behaviour of the opponent.

Notes: Summary The hypoglossal nuclei of adult male albino rats, either normal, or from 1 to 70 days after left hypoglossal nerve transection, were studied cytochemically with a lead method for sodium- and potassium-activated membrane ATP-ase, using light and electron microscopy. Reaction product was measured at the light microscopical level by microdensitometry, and significance determined statistically. Light microscopy revealed a brown reaction product in the neuropil, but none in cell bodies. Blood vessel walls were more strongly coloured. Reaction product was undiminished by ouabain pre-incubation, or by incubation without sodium or potassium, or by incubation with calcium instead of magnesium. Reaction product was diminished by absence of magnesium if calcium was also absent, and abolished if sections were boiled before incubation, or if substrate was absent. Axotomy caused a statistically significant increase in neuropil reaction product in injured nuclei, maximal at 35 days postoperatively, and subsequently decreasing to normal at 70 days. Electron microscopy showed a predominantly surface membrane reaction product, with occasional positive intracellular cisternae. Basal lamina and intra-endothelial vacuoles were also positive. Axotomy resulted in the arrival and disappearance of microglia (2 to 35 days), followed by astrocyte hypertrophy (35 days), and increase in thickness and homogeneity of surface membrane reaction product. The results suggest the presence of one or more calcium- or magnesium-dependent membrane ATP-ases. The peak of the increase after axotomy is probably partly attributable to hypertrophic astrocytes, and partly to the surfaces of neuronal processes. Increase of membrane movements might explain such enzyme activity.

Notes: Summary A method is described, which is suitable to collect continuously and quantitatively saliva from both parotid glands in rats under in vivo conditions and which allows to investigate salivary electrolyte composition in relation to flow rate during several hours. This might be of expanding scientific interest in disturbances of transepithelial electrolyte transport in various pathophysiological situations (for instance different forms of experimental hypertension, endstage renal failure and so on).

Notes: Summary Impaired weight gain, a common feature in experimental chronic uremia, led to compare oxygen consumption values of chronic uremic rats and their controls. Oxygen consumption measurement may allow an approach to the evaluation of total energy requirement. Three groups of animals were considered: uremic rats (CU) of less weight (402.66 ± 9.9 g) than their control group (NA) (498.31 ± 26.13) and younger normal animals (NJ), showing a similar weight (376.0 ± 8.8) to that of the uremics. Significant differences in oxygen consumption values/body weight were found between group NJ (0.927 ± 0.042 ml O2/mn/100 g rat) and both groups CU and NA (0.788 ± 0.036 and 0.788 ± 0.028 respectively). Proportional decrease of energetically active body mass in chronic uremic animals may be the reason of the findings.

Notes: Summary The role of the complement system was studied in Na-taurocholate pancreatitis in rats. Complement activity (CH 50) was determined at various times in the course of pancreatitis. Immediately after induction of acute pancreatitis, serum complement activity declined and massive C 3 deposits could be detected in the vicinity of acinar necroses and necrobioses. After a phase of recovery three to six hours postoperatively a second complement consumption occurred. Lethality rate increased as serum complement activity fell below 50% of preoperative values. The degree of C 3 deposition increased up to six hours. Decline of serum complement activity and deposition within the pancreas seemed to be correlated with histologically demonstrable tissue lesion. The first decline of complement activity in serum is thought to be caused by liberation of complement activating substances within the pancreas due to the detergent action of Na-taurocholate itself. The second decline, however, may be due to the liberation of complement activating and/or destroying enzymes into the blood stream.

Notes: Summary Total hemodynamic values and left ventricular blood flow were studied using Sapirstein's method of 86Rb uptake in female rats 24 h after a last exposure to high altitude. A simulated altitude of 1350 m was used, initial exposure being for 30 min, gradually increased by 30 min daily up to 330 min daily for 5 days a week; the total number of exposures was 32. In another animal group the hypobaric exposure was combined with swimming in water at 37

Notes: Summary Using a highly sensitive antibody to somatostatin, its hypothalamic and extrahypothalamic distribution in the rat was re-examined by light microscopic immunohistochemistry (PAP-method). The scattered somatostatin-producing perikarya occur in multiple layers within the subependymal neuropil surrounding the third ventricle. They supply with short-distance projections the following hypothalamic nuclei: 1) preoptic nuclei (especially their suprachiasmatic and medial components), 2) the peripheral zones of the suprachiasmatic nuclei, 3) the ventromedial and 4) arcuate nuclei, and 5) the ventral premammillary nuclei. Furthermore, the following long-distance projections have been observed: In a rostral direction (A1) rostral of the anterior commissure to the lamina terminalis, (A2) to the OVLT, (A3) to the olfactory tubercle, and (A4) rostrally and caudally by-passing the anterior commissure to the dorsal part of the stria terminalis. More caudally, at the retrochiasmatic level an ascending dorso-lateral projection joins the ventral amygdalo-hypothalamic pathway in a reciprocal manner (B1). In addition, a descending ventrolateral tract projects to the optic tract bending dorsal to it in different directions: (C1) medial to the median eminence, (C2) lateral to the corticomedial amygdala, and (C3) caudal for additional support of the arcuate and ventral premammillary nuclei. The principal tract of somatostatin-containing fibers descends in the subependymal neuropil to the median eminence (D). The results are discussed with reference to a possible participation of the somatostatin fiber system in the afferent branch of the circuit connecting the hypothalamus with the amygdala via the stria terminalis.

Notes: Summary Maternal adrenalectomy at 7 or 14 days of gestation produced increased cell necrosis within zona reticularis cells on the day of birth and at 24 or 48 h after birth. Small remnants or large portions of adrenocortical cells were present within macrophages. In otherwise normal adrenocortical cells, lipid droplets were incorporated within some mitochondria. Autophagocytosis of single mitochondria was observed within adrenocortical cells. Undoubtedly ultrastructural changes represent stimulation of adrenocortical cells in neonatal rats in response to maternal adrenalectomy.

Notes: Summary Vinblastine treatment blocks corticosterone release from rat adrenal zona fasciculata without impairing hormone synthesis, and induces the formation of acid phosphatase-positive granular clumps at the juxta-sinusoidal pole of the cells. Autoradiography shows that ACTH administration to vinblastine-treated animals mobilizes the 3H-cholesterol stored in the lipid droplets and leads to a noticeable labelling of the granular clumps. The possible significance of these granules is discussed.

Notes: Summary In the rat the last generation of oogonia and multiplying prospermatogonia (M-prospermatogonia), frequently arranged in synchronized clusters, enters mitosis on about day 17 post conception (p.c.). The duration of the S-phase D-S-Duration and the minimal generation time T min of both kinds of “gonia” were determined by the method of labeled mitoses (22 female and 22 male fetuses derived from 11 pregnant rats were sacrificed from 2 to 22 h after a single i.p. injection of 3H-thymidine on day 17 p.c.). Three curves, derived from the labeled prophases, metaphases and the postmitotic descendents of oogonia and M-prospermatogonia — oocytes and primary transitional prospermatogonia (T1-prospermatogonia) — were evaluated. It was demonstrated that the curves as well as the calculated values of D-S-Duration and T min are very similar for oogonia and M-prospermatogonia. D-S-Duration ranged from about 10 to 12.5 h (10 h read off from the curves of labeled metaphases), T min from 16.5 to 18 h (16.5 h read off from the curves of labeled metaphases).

Notes: Summary Light microscopic autoradiography was performed subsequent to injection of tritiated amino acids into various parts of the amygdaloid body of the rat. Evidence is provided for two hitherto unreported projections of the amygdala: from the medial amygdaloid nucleus to the contralateral premamillary nuclei and from the central amygdaloid nucleus to the mesencephalic central grey. The functional implications of these findings are discussed.

Notes: Summary Intranuclear microfilament bundles were observed in ependymal cells of the third ventricle of the rat. They appeared as single, cylindricallyshaped fibrillar bands up to 4.9 μm in length. In cross sections of bundles, the microfilaments exhibited an apparently regular arrangement. They were separated by a distance of 4 to 5 nm, measuring approximately 11 nm from centre to centre. One bundle consisted of 55 to 88 microfilaments. The intranuclear bundles terminated at the inner membrane of the nucleus. They exhibited close spatial relationship to perinuclear chromatin, chromatin centres, intrachromatin granules and fibrillar structures. The average ratio of nuclear sections with and without bundles was 1∶15.

Notes: Summary The absolute volumes of the hippocampal and subicular cortical layers in the rat were determined. The boundaries of the various layers were defined on series of sections made through the entire hippocampal region of five rats and stained according to the Timm sulfide silver technique. Coordinates representing the boundaries of the layers on selected sections were fed into a mini-computer programmed to calculate the volume of the layers from the areas of the profiles and the distances between the sections. The distribution of the layers indicates that they constitute the same proportion of the volume of the dorsal and ventral divisions of the hippocampal region, with the exception of the structures lying in regio inferior and regio superior. Although the combined regio superior and regio inferior components of the layers of Ammon's horn occupy the same percentage of the volume of the dorsal and ventral hippocampal regions, the regio superior components occupy a larger percentage of Ammon's horn in the dorsal region than they do in the ventral region. The inter-animal variations in the volumes of the various layers indicate that it is possible to describe quantitatively the subdivisions of the hippocampal region with a precision that is compatible with comparative studies.

Notes: Summary The effects of sex-steroids on the LH-cell development in neonatal rats were studied. The cells were stained immunohistochemically by applying anti-HCG serum. On the second day after birth some of the animals of both sexes were gonadectomized and simultaneously injected with testosterone or estradiol (50 or 200 μg). The remaining animals were either gonadectomized or injected with either one of the sex-steroids. The LH-cell numbers in each group were determined on the 12th day of age from serially cut histological sections of the pituitary. In castrated males the number of LH-cells was about twice that of the intact animals. In the so-called sex-zone, LH-cells tended to be hypertrophied in castrates. These alterations in the appearance of LH-cells did not occur after ovariectomy. In gonadectomized animals injected with sexsteroids (200 μg), the cells were markedly reduced in number and size, both in males and females. Testosterone injection (50 μg) into intact newborn animals also suppressed the numerical development of LH-cells, especially in females. These alterations were particularly evident in the sex-zone in both sexes. Thus the present findings show that sex-steroids may be involved in sexual differences in morphological development of LH-cells in newborn rats.

Notes: Summary This paper deals with the ultrastructure of two types of intranuclear inclusions, “nuclear bodies” and “membranous lamellar bodies”, present in hypothalamic pericytes of intact adult rats. The nuclear bodies exhibited “simple” and “granular” forms, whereas the membranous lamellar bodies were entirely made up of myelin-like membrane whorls. The occurrence of these bodies in nuclei of pericytes has never been previously reported. The origin and functional meaning of such structures is discussed in the light of recent ultrastructural and biochemical studies on nuclear inclusions.

Notes: Summary The regeneration of the vallate papilla in the rat was studied by both light and electron microscopy. The papillae were excised and regeneration was studied at time intervals of 3 to 45 days. It was found that the vallate papilla is capable of regeneration after both partial and total papillectomies. The regenerated papillae were asymmetrical in shape. Several invaginations, independent of one another, were the equivalent of the original sulcus. Regeneration of the gustatory system occurred at circumscribed portions of the associated Von Ebner glands. The amounts of newly formed taste buds were proportional to the amount of nerve fibers in the subepithelial plexus. The regenerated taste buds showed normal histochemical and fine-structural characteristics. The results support the contention of some degree of specificity concerning the epithelium where taste bud regeneration occurs.

Notes: Summary The ultrastructure of intranuclear rodlets, microtubules, fibrillar lattices and membranous inclusions found in the developing cuneate nuclei of rats is described. Rodlets, ranging in diameter from 96–312 nm and in length from 1–2 μm, are made up of tightly packed straight filaments measuring 5–8 nm in diameter. Microtubules with a diameter of 26 nm are clustered together. Fibrillar lattices are made up of fibrils with a diameter of 9 nm arranged in layers or sets. Two to nine sets make up a lattice, with a maximum width of 68 nm, in which the adjacent sets are arranged at an angle to each other. Rodlets and fibrillar lattices occur in 6.8% of the neurons. Membranous inclusions, reported here for the first time in normal neurons, are of 2 types: small vesicles of 0.1–0.6 μm and large vacuoles measuring 1–2 μm. Both types are bounded by either a single or a double membrane and generally have an electron lucent content. Membranous inclusions occur in 25.3 % of the neurons. Changes in the frequency of occurrence of the various intranuclear inclusions in the course of postnatal development are also reported.

Notes: The sperm of the shiner surfperch are packaged into high density aggregations which are introduced into the female genital tract at insemination. Germ cell differentiation occurs within cysts formed by nongerminal Sertoli cells. In late spermiogenesis, spermatozoa within the cysts come to lie parallel to each other and become more densely packed. These sperm packets (spermatophores), containing approximately 600 spermatozoa, then are released into the efferent sperm ducts.The exact nature of the spermatophore binding material is not known, but a major component is proteinaceous and is synthesized in the rough endoplasmic reticulum of the efferent sperm duct epithelial cells. The mechanism by which the spermatophores pass from cysts into ducts is not clear. It appears that whereas many Sertoli cells degenerate causing the cyst wall to break down, many Sertoli cells do not degenerate, but rather assume the configuration of columnar duct cells. The spermatophores remain intact within the testicular ducts, but rapidly dissolve within the female ducts in response to increased pH.

Notes: The telemetered electromyographic activity (EMG) of select hindlimb muscles of unrestrained cats during standing, walking, trotting, and galloping have been recorded. Simultaneous cinematographic records permitted close correlation of muscle activity and locomotor behavior. In general, the pattern of extensor activity of the ankle, knee, and hip during locomotion is fairly consistent, while that of the flexors is more variable.Changes in basic EMG patterns from walk, to trot, to gallop are most evident in the two-jointed muscles associated with the knee and hip. Progressively greater variation of activity onset and cessation can be seen among extensor muscle groups from the walk, to trot, to gallop. Co-activation of the joint extensors and flexors, especially of the hip, at the end of the stance phase (E3) is slight in the walk, moderate in the trot, and considerable in the gallop. These EMG changes are necessary to meet the demands imposed upon the musculature at the faster gaits, particularly galloping, which include limb rigidity as related to loading, momentum as related to the limb's directional change from the stance phase to the swing phase, and lower spinal movements.The peroneal muscles of the ankle and the gluteal muscles of the hip show extensor activity and act as joint stabilizers during locomotion. Both biceps femoris anterior muscle and biceps femoris posterior muscle show consistent hip extensor patterns at all gaits. During quiet standing, extensor activity about the knee, ankle, and metatarsophalangeal joints is evident; but the hip extensor and flexor musculature is remarkably silent.EMG data for unrestrained cats are compared to those of dogs on a treadmill (Tokuriki, '73a,b, '74; Wentink, '76) and those recorded from decerebrate cats (mesencephalic preparation) during controlled locomotion (Gambaryan et al., '71). The EMG patterns from decerebrate cats are more consistent at the walk and gallop within functional groups of muscles at the ankle, knee, and hip than the EMG patterns observed in unrestrained cats or animals moving on a treadmill.

Notes: End-plate distributions have been determined for three frog muscles of different morphology in order to relate end-plate topography to spatial muscle structure and nerve branching. Koelle's cholinesterase technique was applied, both on whole muscles and frozen sections. The end-plates of the short parallel-fibered cutaneus pectoris muscle appeared to be located in short bands along the nerve branches. The nerve tree is restricted to a zonal area across the middle part of the muscle. Depending on the way the nerve branches, the end-plate bands form innervation patterns, varying from one single continuous band to multiple distributed bands. In the latter case one frequently observes that different end-plate bands do not run across the same longitudinal muscle fiber area, although the respective nerve branches run parallel across this area. The long parallel-fibered sartorius muscle has a wider nerve tree and exhibits the same phenomenon for close parallel nerve branches, but end-plate bands along parallel nerve branches far apart cover the same muscle fiber area. The end-plate distribution in the bipennate, short-fibered gastrocnemius is zonal throughout the muscle except in certain compartments containing tonic fibers. The end-plate zone centers around the inner aponeurosis about half-way between the muscle tendon junctions of the fibers and is visible only at the muscle surface where muscle fibers run over their entire length at that surface. The results are of general use in the electrophysiology of neuromuscular transmission because they illustrate how in certain twitch muscles neuromuscular morphology may help to localize end-plates.

Notes: When a larva of Haplothrips verbasci is ready to feed, it grasps the surface of the leaf with its pretarsi, sinks down between its front legs, lifts its head, and places the tip of its mouthcone against the surface. It then shortens its mouthcone and punches a hole in the epidermis by rapidly and repeatedly protracting and retracting its left mandibular stylet. The thrips then inserts its two maxillary stylets as a unit into the wound with a series of rapid thrusts and withdrawals, salivating continuously while doing so. When a food source in the epidermis or mesophyll is found, probing and salivation stop and cibarial pumping begins. Cytoplasm is sucked into the opening at the tip of the protracted stylets, up the food canal between them and into the cibarium.Probing and feeding can occur without mandibular intervention but uptake of liquid seems to require use of the mutually coadapted maxillary stylets, even when these are fully retracted.Prior to molting, the larva protracts its maxillary stylets maximally and, in the pharate state, seems incapable of feeding or drinking.Structures used in feeding are fully described and are shown to resemble those of Hemiptera except for the presence of maxillary and labial palpi and the absence of the loral lobes, right mandible and of a salivary canal between the protracted maxillary stylets. Seven single and 18 paired muscles function in the feeding act, nine less than in adults of the same species.Differences in the feeding mechanism of terebrantian and tubuliferous thrips are discussed and evidence is presented to suggest that the simplified and more highly specialized mouthparts of the latter insects are adaptations for feeding in confining spaces.

Notes: In contemporary entomology the morphological characters of insects are not always treated according to their phylogenetic rank. Fossil evidence often gives clues for different interpretations. All primitive Paleozoic pterygote nymphs are now known to have had articulated, freely movable wings reinforced by tubular veins. This suggests that the wings of early Pterygota were engaged in flapping movements, that the immobilized, fixed, veinless wing pads of Recent nymphs have resulted from a later adaptation affecting only juveniles, and that the paranotal theory of wing origin is not valid. The wings of Paleozoic nymphs were curved backwards in Paleoptera and were flexed backwards at will in Neoptera, in both to reduce resistance during forward movement. Therefore, the fixed oblique-backwards position of wing pads in all modern nymphs is secondary and is not homologous in Paleoptera and Neoptera. Primitive Paleozoic nymphs had articulated and movable prothoracic wings which became in some modern insects transformed into prothoracic lobes and shields. The nine pairs of abdominal gillplates of Paleozoic mayfly nymphs have a venation pattern, position, and development comparable to that in thoracic wings, to which they are serially homologous. Vestigial equivalents of wings and legs were present in the abdomen of all primitive Paleoptera and primitive Neoptera. The ontogenetic development of Paleozoic nymphs was confluent, with many nymphal and subimaginal instars, and the metamorphic instar was missing. The metamorphic instar originated by the merging together of several instars of old nymphs; it occurred in most orders only after the Paleozoic, separately and in parallel in all modern major lineages (at least twice in Paleoptera, in Ephemeroptera and Odonata; separately in hemipteroid, blattoid, orthopteroid, and plecopteroid lineages of exopterygote Neoptera; and once only in Endopterygota). Endopterygota evolved from ametabolous, not from hemimetabolous, exopterygote Neoptera.The full primitive wing venation consists of six symmetrical pairs of veins; in each pair, the first branch is always convex and the second always concave; therefore costa, subcosta, radius, media, cubitus, and anal are all primitively composed of two separate branches. Each pair arises from a single veinal base formed from a sclerotized blood sinus. In the most primitive wings the circulatory system was as follows: the costa did not encircle the wing, the axillary cord was missing, and the blood pulsed in and out of each of the six primary, convex-concave vein pair systems through the six basal blood sinuses. This type of circulation is found as an archaic feature in modern mayflies. Wing corrugation first appeared in preflight wings, and hence is considered primitive for early (paleopterous) Pterygota. Somewhat leveled corrugation of the central wing veins is primitive for Neoptera. Leveled corrugation in some modern Ephemeroptera, as well as accentuated corrugation in higher Neoptera, are both derived characters. The wing tracheation of Recent Ephemeroptera is not fully homologous to that of other insects and represents a more primitive, segmental stage of tracheal system.Morphology of an ancient articular region in Palaeodictyoptera shows that the primitive pterygote wing hinge in its simplest form was straight and composed of two separate but adjoining morphological units: the tergal, formed by the tegula and axillaries; and the alar, formed by six sclerotized blood sinuses, the basivenales. The tergal sclerites were derived from the tergum as follows: the lateral part of the tergum became incised into five lobes; the prealare, suralare, median lobe, postmedian lobe and posterior notal wing process. From the tips of these lobes, five slanted tergal sclerites separated along the deep paranotal sulcus: the tegula, first axillary, second axillary, median sclerite, and third axillary. Primitively, all pteralia were arranged in two parallel series on both sides of the hinge. In Paleoptera, the series stayed more or less straight; in Neoptera, the series became V-shaped. Pteralia in Paleoptera and Neoptera have been homologized on the basis of the fossil record.A differential diagnosis between Paleoptera and Neoptera is given. Fossil evidence indicates that the major steps in evolution, which led to the origin first of Pterygota, then of Neoptera and Endopterygota, were triggered by the origin and the diversification of flight apparatus. It is believed here that all above mentioned major events in pterygote evolution occurred first in the immature stages.

Notes: Oocytes and nurse tissue of Bruchidius differentiate from germ cells during the extended period of pupal development (7.2 ± 0.6 days). A system of 15 pupal stages correlates ovarian development with changes in pigmentation of the eyes, maxillae, alae and tarsalia. The ovarioles grow in length at a constant rate, though their width does not change.A differentiating zone, consisting of germ cells and the basal layer of interstitial cells, arises at the base of the tropharium and separates presumptive oocytes and nurse cells. Early in pupal development the germ cells are arranged in primary syncytia with the cells connected by persisting intercellular bridges filled with fusomal material, never with larger particles, such as mitochondria. At later stages membrane disintegration changes the primary syncytium into a secondary one including all nurse cell nuclei.Nutritive cords are first noticeable when differentiation of oocytes and nurse cells starts. The cords seem to be of primary origin, i.e., they are connections between sister cells which become elongated as these cells are separated during growth. This is indicated by the persistence of intercellular bridges which are sometimes found as part of the membrane of growing nutritive cords connecting young oocytes with the nurse cell syncytium.

Notes: The formation of protein-carbohydrate yolk in the statoblast of a fresh-water bryozoan, Pectinatella gelatinosa, was studied by electron microscopy. Two types (I and II) of yolk cells were distinguished. The type I yolk cells are mononucleate and comprise a large majority of the yolk cells. The type II yolk cells are small in number; they become multinucleate by fusion of cells at an early stage of vitellogenesis. In both types of yolk cells, electron-dense granules (dense bodies) are formed in Golgi or condensing vacuoles, which are then called yolk granules. For the formation of yolk granules, the following processes are considered: 1. Yolk protein is synthesized in the rough-surfaced endoplasmic reticulum (RER) of the yolk cells. 2. The synthesized protein condenses in the cisternal space of the RER and is packaged into small oval swellings, which are then released from the RER as small vesicles (Golgi vesicles, 300-600 A in diameter). 3. The small vesicles fuse with one another to form condensing vacuoles, or with pre-existing growing yolk granules. 4. In the matrix of the condensing vacuoles or growing yolk granules, electron-dense fibers are fabricated and then arranged in a paracrystalline pattern to form the dense body. 5. After the dense body reaches its full size, excess membrane is removed and eventually the yolk granules come to mature. Toward the end of vitellogenesis of the yolk cells, the cytoplasmic organelles are ingested by autophagosomes derived from multivesicular bodies and disappear.

Notes: Testis structure in four species of goodeid teleosts is described. Testicular tubules terminate blindly at the testis periphery where spermatogonia are located. In goodeid teleosts, development of sperm takes place synchronously within cysts whose periphery is made up of a single layer of Sertoli cells. Upon completion of spermiogenesis, spermiation ensues wherein sperm are shed, as spermatozeugmata, into the testis efferent duct system. Subsequently, Sertoli cells, which comprised the cyst periphery, transform into efferent duct cells.Sertoli cells phagocytize residual bodies and are involved in the formation of spermatozeugmata. The structure of the goodeid spermatozeugmatum is quite different from that observed in the related poeciliids. It is concluded, in view of this and other considerations, that the goodeids and poeciliids have independently evolved solutions to the problems of internal fertilization and gestation.

Notes: The papillae basilares of 12 species of lizards from seven different families were studied by SEM. The iguanids, Sceloporus magister and S. occidentalis, have typical “iguanid type” papillae with central short-ciliated unidirectional hair cell segments and apical and basal long-ciliated bidirectional hair cell segments. These species of Sceloporus are unique among iguanids in that the bidirectional segments consist of but two rows of hair cells. The agamids, Agama agama and Calotes nigrolabius, have an “agamid-anguid type” papilla consisting of an apical short-ciliated unidirectional hair cell segment and a longer basal bidirectional segment. Agama agama is unusual in having a few long-ciliated hair cells at the apical end of the apical short-ciliated segment. The agamid, Uromastix sp., has an “iguanid type” papilla with a central short-ciliated unidirectional segment and apical and basal bidirectional segments. The anguid, Ophisaurus ventralis, has an “iguanid” papillar pattern with the short-ciliated segment centrally located. All the short-ciliated hair cells of the above species are covered by a limbus-attached tectorial network or cap and the long-ciliated hair cells, only by loose tectorial strands.The lacertids, Lacerta viridis and L. galloti, have papillae divided into two separate segments. The shorter apical segment consists of opposingly oriented, widely separated short-ciliated cells covered by a heavy tectorial membrane. The apical portion of the longer basal segment consists of unidirectionally oriented hair cells, while the greater part of the segment has opposingly oriented hair cells.The xantusiids, Xantusia vigilis and X. henshawi, have papillae made up of separate small apical segments and elongated basal segments. The apical hair cells are largely, but not exclusively, unidirectional and are covered by a heavy tectorial cap. The basal strip is bidirectional and the hair cells are covered by sallets. The kinocilial heads are arrowhead-shaped.The papilla of the cordylid, Cordylus jonesii, is very similar to that of Xantusia except that the apical segment is not completely separated from the basal strip.The papilla of the Varanus bengalensis is divided into a shorter apical and a longer basal segment. The hair cells of the entire apical and the basal three quarters of the basal segment are opposingly oriented, not with reference to the midpapillary axis but randomly to either the neural or abneural direction. The apical quarter of the basal segment contains unidirectional, abneurally oriented hair cells. The entire papilla is covered by a dense tectorial membrane.The functional correlations of the above structural variables are discussed.

Notes: The circulatory systems of four polystyelids, Botryllus schlosseri, B. primigenus, Botrylloides violaceus and Symplegma reptans, were compared. The palleal buds are connected to the parent zooid by a peduncle and to the colonial vascular system by connecting vessels. The peduncle of S. reptans disappears at an earlier stage of bud development than in B. primigenus; it survives the dissolution of the parent zooid in B. schlosseri and B. violaceus. The connecting vessel is formed by anastomosis between an epidermal outgrowth from the bud and a neighboring colonial vessel, and is characterized by the presence of a sphincter. The number of connecting vessels formed in a palleal bud is three in S. reptans, two in B. primigenus and one each in B. schlosseri and B. violaceus. In each species, the larva has eight rudiments of ampullae. In B. primigenus, the original ampullae degenerate soon after metamorphosis and new ampullae extend from the ventral epidermis of the oozooid. In the other species, the colonial vascular system is derived from the original ampullae.The whole colonial vascular system contracts and expands periodically, with regionally different phases. During each expansion cycle, the sphincter contracts once in B. primigenus and twice in S. reptans. The correlation may be due to blood pressure and the propagation of excitation through the colonial vascular system.

Notes: The mammalian ovary has been studied by optical microscopy and by scanning and transmission electron microscopy with the purpose of presenting an integrated view of the differentiating mammalian follicle. During follicular development, changes in the granulosa cells are particularly noteworthy and include dramatic modifications in cell shape coincident with antrum formation. The cytoplasmic processes of those granulosa cells immediately surrounding the oocyte, as well as the more peripheral granulosa cells comprising a second and third layer, traverse the zona pellucida, infrequently interdigitate with the microvilli of the egg, and make both desmosomal and gap junction contacts with the oocyte. The zona pellucida is thus distinguished by numerous fenestrations of varying diameters. The membrana limitans (basal lamina) is a bipartite structure composed of (a) a homogeneous stratum upon which the peripheral layer of granulosa cells rests, and (b) an outer region of collagen-like fibers. The specific advantages and limitations of the different methodologies utilized to study folliculo-genesis are discussed.

Notes: Papillary projections along the anterolateral margin of the tongue were observed in fetal and young stages of the striped dolphin, Stenella coeruleoalba. Papillary projections appear in the prenatal period and attain maximum development in the early postnatal period. They almost disappear by weaning. Vestigial eminences remain at the corresponding region, but they completely disappear in the adult. The papillary projections observed differ markedly from the lingual papillae of the general mammalian tongue as they are temporary, localized at the anterolateral margin and large in size. The projections were also present in young individuals of some other dolphins. No taste buds could be seen on the projections in any of the stages of all specimens observed. Such projections may have important mechanical functions during suckling in these mammals.

Notes: The fiber composition of the distal accessory flexor muscle (DAFM) and the branching pattern of its excitor axon were compared in several species of crabs, in the lobster and the crayfish. The muscle is composed exclusively of long sarcomere (〉 6 μm) fibers and therefore of the slow type. In all the crab species, except one, there is a distal to proximal gradient of fibers with increasing sarcomere lengths; this gradient is reverse in lobsters and crayfish. A proximal to distal gradient of increasing fiber diameters occurs in the DAFM of all crab species but not in the lobster and crayfish, in which all the fibers are approximately equal in diameter. The single excitatory axon traverses the width of the DAFM and gives off primary branches on either side in the lobster and crayfish but on only one side in crabs. The hypothesis that the axonal branching pattern may govern the regional distribution of fibers with differing sarcomere lengths in proposed.

Notes: The ultrastructure of the pinealocyte in the woodchuck, Marmota monax, was studied during the four seasons of the year. Fall cells have a fairly uniform cytoplasmic density, organelles consistent with synthetic and/or secretory activity and rather extensive pericapillary and intercellular spaces. Many winter pinealocytes are nearly devoid of ribosomes and granular endoplasmic reticulum but contain lipid droplets associated with mitochondria. Pericapillary and intercellular spaces are minimal. Spring glands have the greatest variation in cytoplasmic density with intercellular and pericapillary spaces similar to that seen in fall glands. Cells containing electron dense cytoplasm have Golgi zone associated, secretory granules, free ribosomes, short sections of granular endoplasmic reticulum and dense bodies. Cells with a more electron lucent cytoplasm are similar to the most frequently observed summer pinealocytes which have numerous Golgi zones but few associated secretory granules. Microtubules are prominent in the cytoplasm of these cells, the plasma membranes are smooth and intercellular and pericapillary spaces are minimal. A yearly rhythm or cyclic activity of the pinealocyte is suggested.

Notes: The non-secretory ameloblasts present at the enamel-free surfaces of maxillary teeth in the frog Rana pipiens were examined by electron microscopy at different stages of tooth development. Their main fine structural features seem to reflect a transport function. During early tooth development, the non-secretory ameloblasts adjacent to odontoblasts and predentin exhibit extensive lateral surface specializations and numerous cytoplasmic vesicles. During late tooth development, the non-secretory ameloblasts adjacent to mineralizing dentin show numerous cellular junctions, well-developed intercellular channels with numerous interdigitating processes and labyrinthine configurations at their distal surfaces. An intact basal lamina is present between the non-secretory ameloblasts and the dentin surface until the dentin becomes fully mineralized. At this stage the adjacent cells no longer exhibit surface specializations.It is suggested that the non-secretory ameloblasts may participate in the mineralization of adjacent dentin at the enamel-free surfaces. This surface dentin becomes fully mineralized at a later stage of development than the underlying dentin.

Notes: The developmental morphology of regenerating male breast feathers of the jungle fowl was studied at the ultrastructural level. The process of keratinization was observed in the three types of cells which form feather barbs: barbule cells, cortical cells, and medulla cells. Keratinization first became evident in the barbule cells and resembled the process of keratinization as observed in hair cortical cells and embryonic down feathers. Eventually the whole cytoplasmic area of the barbule cell was occupied by keratin.The barb cortex cells became keratinized in a similar fashion as the barbule cells but not until they were developmentally twice as old as the barbule cells. When keratinization was complete in these cells, the keratin was in the form of large agglomerates scattered in the cytoplasm.The barb medulla cells showed no obvious signs of keratinization until they were developmentally three times as old as the barbule cells. Keratin filament bundles were first seen near the plasma membranes of the medulla cells. Large empty vacuoles appeared in the cytoplasm which also contained moderate amounts of glycogen.

Notes: The ultrastructure of neuromuscular junctions in the twitch fibers of the stapedius muscle of Gallus gallus (domesticus) was investigated as part of a series of neurophysiological studies. Among the morphological features observed were elongated end-plates with numerous large and clear synaptic vesicles mixed with larger dense core vesicles and irregular or aperiodic “active sites” in the presynaptic membrane where synaptic vesicles were focused. The most remarkable features of these junctions were large synaptic clefts (50-80 nm) and the absence of junctional folds in the sarcolemmal surface. Unlike the large periodic junctional folds seen in the neuromuscular junctions of frogs and in the fast twitch fibers of the mammalian stapedius, the preparations studied only show small aperiodic invaginations (primitive folds) in the postsynaptic membranes. This morphological feature remains essentially constant from newly hatched to adult chickens. While these smooth junctions are consistent with earlier findings of inconspicuous junctional folds in the twitch fibers of the chicken posterior latissimus dorsi they are unlike those seen in the fast twitch fibers of the mammalian stapedius muscle, or other twitch fibers in general. The morphological findings of the present study may also suggest that the simple, unmodified neuromuscular junctions in the stapedius of Gallus may be a useful preparation for studies of synaptic membrane structures that employ the freeze-fracture technique.

Notes: A skeletal neomorph - the preglossale - is described from the tip of the tongue in Passer. This medial unpaired skeletal element is a dorsally open trough articulating with the anterior tips of the paraglossalia and supporting the heavy epidermal pad of the seed-cup. The large paired Mm. hypoglossus anterior originate from the posterior half of the preglossale and insert onto the anterior bodies of the paired paraglossalia; they serve to depress the anterior portion of the preglossale. A regular pattern of dermal papillae is present in the seed-cup; these are arranged in about 20 rows of six to 8 papillae per row. Each papilla contains a series of Merkel cells and associated nerve endings (touch receptors). The seed-cup serves to orient and hold the seed in place while it is being husked; the battery of tactile receptors provides information on the position of the seed on the tongue. The preglossale serves to support the seed-cup and to change its shape - the curvature of the dorsal surface - as it is depressed relative to the paraglossalia. The paraglossale and associated features of the seed-cup in Passer would provide a valuable preparation to study a diversity of problems such as developmental interactions between endomesodermal and ecto-mesenchymal skeletal features, the ontogenetical development of Merkel cells, and the sensory physiology of Merkel cells and their associated nerve endings as tactile corpuscles.

Notes: The structure of the longitudinal zebra stripes on the thorax of adult Zaprionus vittiger has been investigated by light-, polarization-, transmission electron-, and scanning electron microscopy. Each stripe consists of a central white stripe of about 50 μm width and two lateral dark brown stripes about 30 μm wide. Three different types of trichomes occur: Very long bent trichomes of the grooved-type, long bent trichomes of the crested-type, and short straight trichomes. The central white stripe contains neither bristle organs nor short straight trichomes but carries many long bent trichomes most of which are of the grooved type, contain two cavities and polarize the light in the polarization microscope. The dark brown stripes carry bristle organs and many trichomes of the short and straight-type. Bent trichomes of the crested-type are found on the whole zebra stripe at about equal frequencies; they contain no cavities and do not polarize the light. The cuticle of the dark stripes is underlain by pigment cells. It is suggested that the pigment granules in the epidermal cells cause the dark color of the dark brown stripes, whereas the form and structure of the bent grooved type trichomes cause the white color of the central stripe.

Notes: New data on the brain of Latimeria indicate that previous estimates of the brain weight were too high by a factor of two. Our data suggest a brain weight of 1.1-1.5 grams for a specimen with a body weight of 30 kilograms. Quantitative data on major divisions of the brain are presented for the first time, and the relative size of the major brain divisions is similar to that of sturgeons and generalized sharks (such as hexanchids and squalids). Examination of brain component weight (s): body weight plots in a sample of non-teleost actinopterygian fishes indicates that all major divisions of the brain, except the telencephalon, are larger than in Latimeria. Brain component sizes in Latimeria are more similar to those extrapolated for amphibian brains than to those for actinopterygians. However, the cerebellum of Latimeria is considerably larger than that of amphibians.

Notes: The Champy-Maillet osmium tetroxide-zinc iodide technique and a new method using azur B-sodium thioglycolate were used to study the general nervous tissue structure in planarians. A subepidermal and a submuscular nerve plexus, partially reported by earlier authors, are described, and a gastrodermal plexus is reported for the first time in triclads. The possible functions for each one of these plexuses are discussed. By the Champy-Maillet method, the innervation within the parenchyma appears as an array of numerous single nerve fibers that course between the parenchyma cells making apparent synaptic contacts. The pharynx has outer and inner nerve nets similar in structure to the submuscular nerve plexus. Both nerve nets are connected to each other by radial nerves.The central nervous system has a sponge-like structure with many lacunae filled with cell bodies, dorso-ventral muscle fibers, parenchymal cell processes and excretory ducts. The existence of this sponge-like nervous tissue structure is discussed in relation to the still incomplete centralization of the nervous tissue in these organisms, to the lack of a true vascular system and to the acoelomate level of organization. A comparison with the nervous tissue structure of more advanced groups like polyclads and nemertines is suggested.

Notes: The gross morphology of the nervous system supplying the dorsal longitudinal flight muscles of tsetse flies is described. Electron microscopical investigation of the nerves reveals that the dorsal longitudinal muscles are innervated by branches from four main axons. A detailed description of the neuromuscular junctions in the flight muscle is presented.

Notes: Projection microradiography was used to determine the density and orientation of the force transmitting structures, i.e., trabeculae and bone lying between approximately parallel vascular canals, within the bones of cat skulls. The organisation in the skulls was confirmed statistically for a total of ten cats. The results of the observations showed that within specific areas of the skull a high degree of structural orientation and an increased density of osseous structures was present. The distribution of these characters corresponded in contiguous bones such that a continuum of structural organisation was established between the alveolar region and the site of attachment of the temporalis and masseter muscles and the glenoid region.The patterns of force transmission during jaw closure were determined when a resistance was placed initially between the canines and then the carnassials. An analysis was first carried out on dry skulls using colophonium resin to determine the direction of the force distribution. The nature and the approximate magnitude of the forces were ascertained by replacing the resin with strain gauges. The basic similarities in the strain patterns recorded from the dry skulls and those from the ten anaesthetised cats in which strain gauges had been intra-vitally implanted, substantiated the recordings made on the dry skulls. Combination of the results from the three sets of experiments defined the patterns of force distribution in the cat skull during the closure of the mandible against a resistance. The results showed that: (1) the combined action of the temporalis and masseter muscles tended to reduce the overall strain in the skull bones, and that the deformations produced by the action of the masseter were greater than that exerted by the temporalis muscles; (2) during biting, whether the resistance was placed between the canines or carnassials, compressive forces predominated in the facial bones; (3) small movements observed between facial bones indicated the presence of a flexible component within the skull, thus allowing large forces to be exerted during biting without overstressing the facial bones; (4) the glenoid fossa is part of a force bearing joint; (5) forces generated during biting were resisted within the skull by forces of an opposite nature generated within the system, the incompressible nature of bone and by the effect of the soft tissues; (6) the nature and the magnitude of the strain altered when a resistance was placed at the canines and then at the carnassials; however, the pattern of force distribution within the skull remained the same; (7) there was a direct correspondence between the detailed structural organisation of the bones and the patterns of force distribution. This conclusion would appear to apply in general to mammalian skulls. The study also emphasises the importance, neglected hitherto, of carrying out a variety of experiments to determine the patterns of force distribution in bones.The Trajectorial Theory of bone organisation is discussed and, on the basis of the results obtained, a modified theory is proposed. This states that: the structural continuum is common to the compact and cancellous bone and comprises bony bars which are aligned in the optimum direction for the transmission of force to a region in the bone or bones where it is effectively resisted.

Notes: There are two discrete lobes comprising the armadillo subman-dibular gland. These two lobes can be defined grossly, histochemically and morphologically with the light and electron microscope. The minor lobe stains more intensely with PAS and AB. When viewed in the electron microscope, the secretory granules of the acinar cells within this lobe appear mucous-like. The granules of the demilune cells are slightly different in appearance. The secretory granules of the acinar cells in the major lobe contain many dense foci embedded in a fibrillar matrix, a substructure not described previously. The demilune cells of this lobe contain secretory granules with a mucous-like structure which is consistent throughout the entire lobe. As in the minor lobe, these demilune cells stain very intensely with PAS and AB.

Notes: The relationship of the cells and tissues which comprise the developing ovarian follicle in Xenopus laevis has been studied with scanning and transmission electron microscopy. The saclike ovary is covered on its coelomic side by a squamous epithelium. The cells of this epithelium are extensively interdigitated, and each bears a short, centrally positioned cilium. The lumenal surface of the ovary is covered with a layer of nonciliated squamous cells. The areas of cell-cell contact are characterized by desmosomes in both epithelia, and between the epithelia lies a connective tissue layer-the theca-which contains collagen fibers, blood vessels, nerves, smooth muscle cells and oogonia. Beneath the theca in each follicle lies a single layer of flat stellate follicle cells. Associations between adjacent follicle cells are intermittent, leaving wide spaces or channels. Junctional contacts between neighboring follicle cells are characterized by desmosomes. From the basal surface of each follicle cell extend long, broad macrovilli which penetrate the underlying acellular vitelline envelope and contact the surface of the oocyte. Evidence is presented which suggests that follicle cells may produce and release components which participate in the formation of the vitelline envelope which consists of a 3-dimensional lattice of ropey fibers. Passageways through the vitelline envelope allow the maintenance of contact between oocyte and follicle cells and also allow ready penetration of materials both to the oocyte (e.g., vitellogenin) and from it (e.g., cortical granule material) at different stages of its development.

Notes: This study reveals age related changes in the microscopic structure of the paired frontal bone of the domestic rabbit. Undecalcified ground sections were prepared from anterior frontal bone slices removed from New Zealand White rabbits ranging from birth to 24 months of age. Included were 40 females, 4 males and 6 rabbits less than 14 days old of unknown sex. The ground sections revealed both qualitative and quantitative age changes. Qualitative changes include change in bone tissue types and developmental processes, and presence or absence of primary and secondary osteones. Quantitative changes were measured by counting primary osteones in the outer table of each frontal bone half within 1.6 mm of the metopic suture. In this region, primary osteones were absent at birth, limited in number at 14 days and generally numerous between one and three months of age. In animals older than three months, numbers of primary osteones generally decreased with increasing age. No animals older than 16 months revealed primary osteones. Possible sources of variability in the relationship between observed primary osteone number and age include ability to recognize primary osteones, methods of sampling and processing bone slices, sex related differences and diseases afflicting specimen. Significance of this study includes increased knowledge of frontal bone growth and histology.

Notes: The ascophoran Pentapora foliacea was studied from epoxy sections of skeletal and soft (hard-soft) tissues. The basal wall is double, indicating the colony grew as two independent layers, back to back. The structure of the vertical walls and interzooidal communication organs indicates that zooids were budded in the usual way as in most encrusting cheilostomes. Secondary layers of the frontal wall are of acicular aragonite. The ovicell develops as a flattened cuticular bladder in early ontogeny; the aragonitic layer of the frontal wall later engulfs it. A median vesicle, an evagination of the vestibular wall, is present but the eggs may be supplied with sufficient yolk to nurture the embryo. The overall ovicell structure is similar to that of hyperstomial ovicells in other cheilostomes.

Notes: This investigation describes the pre-natal morphogenesis of the type I pneumocyte subsequent to its differentiation from pulmonary epithelium. Cells lining subpleural alveolar septa were photographed from serial sections with the electron microscope, and a three-dimensional representation of each cell was obtained by transferring the contours of the cell membranes from montages to transparent plastic sheets which were then spaced to scale and stacked. The results of this study indicate that: The nascent blood-air barrier of a 50-day reconstructed cell was twice as thick as the average definitive barrier; definitive barrier thickness was observed in some areas in a 63-day reconstructed cell; the amorphous component of elastic tissue which appears peripherally in septal connective tissue during pre-natal morphogenesis may be directly juxtaposed to the basal lamina of the alveolar epithelium; the orientation of the cell junction between a pneumocyte and its neighboring cells, as observed in sections of alveolar septa, changes as the contour of the pneumocyte changes from simple abutment to overlapping patterns.

Notes: The fine structure of the mid-gut musculature of the desert locust, Schistocerca gregaria is described and compared with that of the visceral muscles of other species. The gross morphology and fine structure of the nervous system which supplies the mid-gut muscle fibres is described.

Notes: The integument of Paranthessius anemoniae has been studied with light and electron microscopy. A cuticle with clearly defined epicuticular, exocuticular and endocuticular regions overlies a cellular hypodermal layer. The distribution of carbohydrate, lipid and protein components of the cuticle were demonstrated histochemically. Parabolic striations in oblique sections of cuticle suggest that its molecular architecture fits a “twisted sheet” theory proposed for other species.Arthrodial membranes at body and limb joints have a homogeneous structure, lacking exocuticle and endocuticle. Subcuticular glands appear to secrete substances thought to be responsible for the immunity which Paranthessius seems to have to the nematocysts of its host. Small hairs, situated in cuticular cups which occur over the dorsal body surface are considered to function as rheoreceptors.

Notes: The larval epithelium of the sea urchin, Lytechinus pictus, consists of squamous cells and bands of columnar epithelial cells bearing cilia. During metamorphosis this tissue undergoes a series of rapid, complex changes. Through the scanning and transmission electron microscope, we describe and analyse these changes. The changes can be divided into three steps. (1) The larval arms bend away from the left side of the larva, exposing the urchin rudiment. Cells which are identical to smooth muscle cells are in a position to bring about this bending. (2) The squamous epithelial cells assume a cuboidal shape. This change in shape results in the collapse of the larval epithelium onto the presumptive aboral surface. These cells possess a subapical band of microfilaments. The cellular shape change but not the bending of the arms is reversibly inhibited by Cytochalasin B. These observations suggest a mechanism for this change. (3) The former lining of the vestibule of the urchin rudiment comes to lie over the collapsed larval tissue and forms the adult epithelium. At this point, after only one hour, the larva has assumed the external shape of an adult sea urchin.

Notes: This paper reports new observations obtained from a study of macronuclear fine structure throughout various stages of the cell division cycle of Euplotes. Study of the ultrastructural organization of the macronuclear chromatin indicates that much of the chromatin is organized into continuous masses, portions of which appear to be attached to the nuclear envelope. The macronuclear envelope appears unchanged in the region of a replication band, and apparent attachments of the chromatin to the inner membrane of the nuclear envelope are maintained in the reticular and diffuse zones. Intranuclear helices were never observed in the diffuse zone. During macronuclear division, linear elements (fibrils or microtubules) were observed in close association with both chromatin bodies and nucleoli. The ultrastructural data suggest that the intranuclear linear fibrils have two functions: elongation of the dividing nucleus, and attachment of chromatin bodies and nucleoli to the envelope. The significance of these observations for macronuclear division and chromatin segregation is considered.

Notes: The forelimbs of anteaters play a major role in obtainment of food, defense, and locomotion. The greatly enlarged claws on the manus are used for ripping open insect nests and insect-infested wood; the claws also serve as the animals' only defensive weapons, since they lack teeth. Specialization of the claws for these functions has also had a substantial effect on the ways in which the forelimb is used for posture and locomotion.Modifications of the forelimb in the anteater Tamandua include the following. Attachments of the medial head of triceps are rearranged so as to greatly increase capability for powerful flexion of the claws. Ability to flex the elbow and to retract the humerus is also augmented; these movements would assist digital flexion in applying traction with the claws to material being torn away during food procurement. This traction can be supplemented by a variety of powerful side-to-side and/or twisting movements of the hand, brought about primarily by axial rotation of the upper arm and forearm. The digital joints are reinforced to resist the deviational and torsional loading to which the digits would be subjected during such movements.The morphological modifications of the forelimb in Tamandua are discussed in terms of how they affect the mechanical capabilities of the limb, what functions the limb is best designed to perform, how they may relate to what little is known about the specialized behavior of this animal, and what behavioral predictions may be made based on mechanical design.

Notes: The olfactory system of the pigeon (Columba livia) was examined. Our electrophysiological and experimental neuroanatomical (Fink-Heimer technique) data showed that axons from the olfactory bulb terminated in both sides of the forebrain. The cortex prepiriformis (olfactory cortex), the hyperstriatum ventrale and the lobus parolfactorius comprised the uncrossed terminal field. The crossed field included the paleostriatum primitivum and the caudal portion of the lobus parolfactorius, areas which were reached through the anterior commissure. In this report the relationships between areas that receive olfactory information and the possible roles that olfaction plays in the birds' behavior are discussed.

Notes: Adult newts (Notophthalmus viridescens) were lentectomized and at intervals from 4 to 21 days after lentectomy iridocorneal complexes from these animals were examined by scanning electron microscopy to allow a full appreciation for the shape of the regenerating lens. Until around day 12 after lentectomy the posterior surface of the iris is covered by a dense mat of fibrous material which cannot be removed without damage to the iris and which obscures the events of cytoplasmic shedding. The regenerate becomes visible first around stage IV (day 12). A small but clear groove demarcates the regenerate from the rest of the iris. As regeneration progresses there is a marked reduction in debris on the iris surface and the regenerate appears as a U-shaped thickening occupying about one-third of the dorsal half of the iris. During later stages (VI-X) the regenerate protrudes into the pupil inferiorly and posteriorly towards the retina, but does not encroach laterally on the remaining pigmented iris tissue. Prior to secretion of the lens capsule the outline of individual cells is visible on the surface of the regenerate and some regenerates exhibit a prominent dimple on their posterior aspects. Following secretion of the capsule the surface of the regenerate becomes smooth. Quantitative studies show that volume and maximum section area of the regenerate are both more strongly correlated with developmental stage of regeneration than with time after lentectomy.