Distribution of cat fleas (Siphonaptera: Pulicidae) on the cat

A total of 3,382 cat fleas, Ctenocephalidesfelis (Bouche), was taken from 164 of the 200 stray cats examined. It was observed that cat fleas preferred specific areas on the cat. A significantly higher mean number of fleas was found on the area of head plus neck than on the ventral part of the body. More specifically, the mean number of fleas was highest on both of the neck and dorsal areas. However, in terms of the density of fleas, the neck had more fleas than the dorsal area did. The fewest fleas were found infesting the legs and tail. Distribution of fleas on the cat may well be explained by the various grooming patterns of the cat, and the knowledge of flea distribution may be valuable for application of on-animal flea control procedures.     

Ultrastructure of the cat sublingual gland

The sublingual gland of the cat consists primarily of branched secretory tubules that open into an abbreviated duct system. The simple epithelium that composes the secretory tubules consists of an admixture of mucous and serous cells, with the former predominating. Some secretory tubules are capped by a serous demilune. Regardless of position, almost all serous cells have prominent basal folds and border on at least one intercellular canaliculus as well as on the tubule lumen. Serous cells possess an extensive array of irregular, distended cisternae of rough-surfaced endoplasmic reticulum that frequently contain dense intracisternal granules. Serous granules are relatively few in number and rarely show evidence of substructure. Mucous cells, which lack basal folds, contain an apical mass of secretory material in the form of partially fused droplets. The duct system is somewhat less ordered than in most major salivary glands; secretory tubules empty into structures resembling intercalated ducts or may be in direct continuity with ducts intermediate in morphology between intercalated and excretory ducts. The absence of striated ducts noted in this study may be correlated with the high sodium content of cat sublingual saliva. The main excretory duct of the sublingual gland closely resembles that of the cat submandibular gland in terms of morphology, but exhibits little of the transport functions reported in the latter duct.     

The contrast sensitivity of the cat

1. The experiments were carried out on pretrigeminal cats.2. By recording potentials evoked from the visual cortex by a grating stimulus, it was established that there was a linear relation between the voltage generated and the logarithm of the contrast of the grating.3. The voltage evoked by the grating was independent of the orientation of the grating.4. It has previously been shown in man that, if the contrast is determined by an extrapolation to the point at which a zero voltage occurs, this value corresponds to the psychophysical threshold. On the assumption that the threshold of the cat also occurs at zero voltage, thresholds for a number of spatial frequencies and orientations were determined.5. When the threshold sensitivity function for the cat is compared with man it is found to be displaced to lower spatial frequencies by a factor of about ten. This means that while the cat cannot see such high spatial frequencies as man, it can see lower frequencies better than man.     

Dystrophy-like myopathy in the cat

Two cases of feline myopathy are described which were associated with moderate locomotor disturbances. At necropsy, a pale coloured skeletal musculature was found with severe hypertrophy of diaphragmatic musculature. Histologically, the myopathy was characterized by varying fibre diameter, internal nuclei, moderate degeneration and necrosis of solitary muscle fibres and slight to moderate endomysial and perimysial fibrosis. Only very few regenerating muscle fibres were present. The histological findings are compatible with those found in human muscular dystrophies and so this feline myopathy may be considered as a dystrophy-like myopathy.     

Efferent projections of the pretectum in the cat

Summary Direct projections from the pretectum in the cat were investigated by means of the Nauta-Gygax and the Fink-Heimer method in an attempt to identify the morphological substrates subserving possible neural mechanisms involved in visual behaviour and reflexes.Degeneration in the diencephalon was found ipsilaterally in the nucleus limitans, lateral pulvinar nucleus, lateral posterior nucleus, lateral dorsal nucleus, dorsal and ventral lateral geniculate nuclei, centre medianparafascicular complex, central medial nucleus, paracentral nucleus, central lateral nucleus, ventroanterior and ventrolateral nuclear complex, zona incerta, H field of Forel and the reticular nucleus. The pretectal fibers projecting to the ventral lateral geniculate nucleus appeared to be topically organized.In the midbrain, the pretectal fibers were observed to terminate ipsilaterally within the superior colliculus, nucleus of Darkschewitsch, dorsolateral portion of the red nucleus, lateral terminal nucleus of the accessory optic tract and the reticular formation, and bilaterally within the central gray, interstitial nucleus of Cajal and the rostral portion of the nucleus of Edinger-Westphal. Degeneration in the superior colliculus was marked in laminae II, III and IV. The fibers arising from more anterior part of the pretectum appeared to be distributed more medially in laminae II and III.The pretectopontine fibers terminated ipsilaterally in the paramedial and the dorsolateral pontine nuclei as well as the reticular formation. In the inferior olivary complex, degeneration was found in caudal levels of the dorsal cap and -nucleus, and additionally in the rostral portion of the dorsal accessory olive.     

Sex dimorphism in the skull of the cat

There are differences in the skull of male and female cats. The temporal line of each parietal bone which lies close up to the median in the male cat, is a laterally curved line in female cats and castrated males. The temporal line continues to the external crista of frontal bone and forms in this way with the other side a small parietal plane in the male, and a arched one in female and castrated males. This is possibly caused by a sex hormone dependent formation of temporal muscle.     

Gamma-aminobutyrate-like immunoreactivity in the thalamus of the cat

Serial sections of the cat's thalamus were incubated with a purified antiserum raised against gamma-aminobutyric acid conjugated to bovine serum albumin by distilled glutaraldehyde. This serum has been extensively characterized and appears to react selectively with fixed gamma-aminobutyric acid in brain tissue treated with glutaraldehyde. Adjoining sections were stained with thionin and served as invaluable guides for a correct evaluation of the immunolabelling pattern. In the neuropil the intensity of the immunostaining varies considerably between thalamic nuclei and even between nuclear subdivisions. The neuropil staining appears particularly dense in the nuclei parataenialis, periventricularis, centralis medialis, reuniens, rhomboideus, habenularis lateralis, centrum medianum, parafascicularis, subparafascicularis, submedius, dorsal and ventral parts of the lateral geniculate body, the dorsal part of the medial geniculate body, the posterior complex, suprageniculate nucleus, pulvinar and parts of the lateral posterior nucleus. The pulvinar/lateralis posterior complex shows a particularly well-differentiated staining pattern which closely matches Updyke's [Updyke (1983) J. comp. Neurol. 219, 143-181] parcellation of this region. In several thalamic nuclei or subareas--and notably in those relay nuclei which are known to project upon non-primary sensory cortical areas--the immunostained neuropil is characterized by many puncta encircling an unstained profile. With few exceptions all thalamic nuclei displayed immunoreactive nerve cell bodies. Several examples were found of a mismatch between the number of such cells and the staining intensity of the neuropil. Thus the nuclei periventricularis, parafascicularis, subparafascicularis, parataenialis, limitans and centrum medianum although being very rich in neuropil staining have practically no immunostained perikarya. Rough estimates were made of the size and the proportion of gamma-aminobutyric acid labelled neurons in all major--and some minor--thalamic nuclei and their subdivisions. In some thalamic nuclei, notably the nuclei reticularis, anterior dorsalis, lateralis dorsalis, centralis lateralis, ventralis posterior and the dorsal lateral geniculate body, the population of immunoreactive neurons is distinctly heterogeneous with regard to soma size. The findings are discussed with regard to previous immunocytochemical studies of the distribution of gamma-aminobutyric acid and its synthesizing enzyme in the thalamus. Particular emphasis is put on the great species differences which appear to exist in this respect.     

Polyglucosan bodies in the brain of the cat

Polyglucosan bodies (PGB) were examined by light and electron microscopy in the brain of cats without neurological signs. PGB in the feline brain were round, basophilic, PAS-positive, filamentous structures. Both morphologically and histochemically, PGB in the cat were identical to Lafora bodies and similar structures found in man and other animals. Most of the bodies were situated in the neuronal processes, but were not found in perikarya. PGB were disseminated throughout the brain, especially in the cerebral cortex, midbrain, cerebellum and medulla oblongata. The occurrence of PGB in the feline brain may represent an ageing phenomenon.