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At least 55 records · Page 3Linked to original sources
PubMed1986

Ultrastructural characterization of the retrovirus particles (Sm-MTV) liberated from the mammary tumor cell line (Sm-MT) of a house musk shrew, Suncus murinus (Insectivora).

Detailed ultrastructure of a new type of retrovirus (Sm-MTV) released by cultured cells (Sm-MT) of a spontaneous mammary tumor from a house musk shrew Suncus murinus, Insectivora, is described. The virus particles were revealed as three forms: intracellular; budding; and extracellular. The intracellular type A particles were similar in profile to those associated with mouse mammary tumor cells and tended to form a small cluster of several particles in the cytoplasm. In addition, horseshoe-shaped particles as well as smaller particles in clusters, with doughnut-shaped morphology similar in structure to type A particles, were identified near the clusters of type A particles, although in smaller numbers. The budding particles contained a doughnut-shaped nucleoid, although the nucleoids decreased in size as compared with intracytoplasmic type A particles. The extracellular virions consisted of an envelope and a centrally located nucleoid. In routinely fixed specimens, the former was covered with irregularly distributed fuzzy materials in its surface, and the latter was further composed of a small electron dense core surrounded by an intermediate layer. Tannic acid treatment of cells resulted in the visualization of surface projections on the envelope of virions. Similar projections were also detected exclusively on the plasma membrane where virus budding took place, and not on the normal plasma membrane. The presence of surface projections on the viral envelope was further confirmed by the whole-cell-mounting technique. Together with our previous results of biochemical and immunological investigations, we concluded that Sm-MTV seemed to have closer phylogenetic relatedness with type D viruses of primates than with murine mammary tumor virus.

Animals↗
PubMed1989

Topography and cytoarchitectonics of the nuclei of the posterior part of hypothalamus in Insectivora. Part I. Nuclei corpis mamillaris.

Studies were carried out on the brains of three adult mammals: hedgehog, mole and common shrew. Paraffin cross-sections 15 microns thick were stained with the methods of Nissl and Klüver-Barrera. The paper gives a description of the location, shape and cell structure of the nuclei of corporis mamillaris in the three mammals. Studies suggest that location of nuclei in corpus mamillaris of Insectivora is similar, while their shape and cell structure are characterized by typical species-related differences. These differences are noticeably less pronounced in mole and common shrew, the 2 species differing from hedgehog. In case of hedgehog, the differences consist most of all of different shape of nucleus mamillaris medialis and nucleus supramamillaris and of different cell structure of nucleus tuberomamillaris pars posterior. In hedgehog corpora mamillare are characterized by progressive phylogenetic development compared to corpora mamillare in mole and common shrew.

Animals↗
PubMed1986

A Golgi study of the sixth layer of the cerebral cortex. I. The lissencephalic brain of Rodentia, Lagomorpha, Insectivora and Chiroptera.

A study of the morphological characteristics of the neurons in layer VI of the cerebral cortex was carried out using the rapid Golgi method in several lissencephalic species including Rodentia (rat, mouse, vole (Microtus agrestis) and hamster), Lagomorpha (rabbit), Insectivora (hedgehog) and in the Chiroptera the dwarf bat (Pipistrellus pipistrellus). There was a basic uniformity in the structure of the sixth layer. Main neuronal types in lamina VIa were large pyramidal neurons, triangular or atypical pyramidal cells, multiapical pyramidal neurons, inverted pyramids, fusiform neurons, Martinotti cells and bi-tufted cells. Main neuronal types in lamina VIb were medium sized, flattened pyramids, large and small horizontal neurons, horizontal pyramidal cells, fan shaped neurons and multipolar spinous neurons with long descending axons. Sparsely spinous and spine-free multipolar neurons with short axons were present in the two laminae of layer VI, but sparsely spinous neurons with axons similar to those found in basket cells of other layers of the cortex were observed mainly in lamina VIa. Neuronal subsystems were tentatively classified on the basis of the course of the axons. Pyramidal neurons, fusiform neurons, multiapical pyramidal cells, inverted pyramidal cells, fan shaped neurons and multipolar neurons with large descending axons were interpreted as being the main source of long projection and association connections. Large horizontal neurons were interpreted as possible ipsilateral association neurons because the horizontal course of the axons over long distances followed the boundary of the deeper region of the sixth layer. Three intracortical (association) subsystems were included. Axons of Martinotti cells and collateral ascending axons of pyramidal neurons (including multiapical pyramidal neurons) formed the ascending interlaminar fibrillary subsystem. Axons of small horizontal cells and horizontal collaterals of pyramidal neurons formed the horizontal intracortical subsystem. Sparsely spinous and spine-free multipolar neurons and bi-tufted cells were the main source of the local, non-horizontal fibrillary subsystem.

Anatomy, Comparative↗
PubMed1984

Comparison of brain structure volumes in insectivora and primates. V. Area striata (AS).

Volumes of the area striata (area 17, Brodmann) were measured in 44 species of Primates and Scandentia and some of its laminar components in 25 species. The relative size (expressed by size indices) is on the average distinctly larger in simians than in isoponderous prosimians. The average dimensions of increase are 2.5 times for total area striata (ASV), 3.4 times for white matter (ASW), 2.35 times for grey matter (ASG), 1.9 times for lamina 1 (ASG 1) and 2.4 times for laminae 2-6 (ASG 2-6). The high increase of the white matter and the low increase of lamina 1 both correspond to similar results on the total neocortex (Frahm et al., 1982). The molecular layer (ASG 1) is on the average about 12% of the total area striata grey (ASG). The visual cortex thus has a narrower molecular layer than the neocortex as a whole, in which an average of 14% was found. The size indices of man are within the simian range and generally slightly above the simian average. Tree shrews have relatively small visual cortices, but reach into the lower part of the prosimian range. For Insectivora, ASG volumes were estimated from CGL volumes. According to these estimates, the relative ASG size is about 1/90 in shrews, about 1/40 in tenrecs and about 1/10 in hedgehogs that of isoponderous prosimians. In the European hedgehog, the area striata is about 12% of the total neocortex, a value similarly to that found in area measurements by Brodmann (1913). The relative size of the area striata is discussed with regard to functional, ecoethological and phylogenetic considerations. With increasing body weight, the increase in the visual structures, both cortical and non-cortical, is weak when compared with other brain parts and body organs (strongly negative allometry).

Animals↗
PubMedDate not supplied

Fine structure of the submandibular salivary gland of the venomous short-tailed shrew, Blarina brevicauda Say (Insectivora: Soricidae).

Adult male short-tailed shrews, Blarina brevicauda, (Insectivora: Soricidae) were trapped in Virginia and Pennsylvania, anesthetized, and perfused via the left ventricle of the heart with fixative. The submandibular glands were dissected free and prepared for transmission electron microscopy. The lobular, compound tubuloacinar glands had secretory endpieces consisting of seromucous acini and serous tubules connected to intercalated ducts, granular ducts, striated ducts, and excretory ducts. The general cytology of the submandibular gland of Blarina shared morphological characters with individuals in several other mammalian orders and yet differed in many ways from another Insectivore, the European hedgehog, Erinaceus europaeus.

Animals↗
PubMed1996

Ovotestis variability in young and adult females of the mole Talpa occidentalis (insectivora, mammalia).

The age-related evolution and ontogenic origin of the ovotestes in fertile females of the Spanish mole (Talpa occidentalis) were studied. Volume of the ovotestis and its ovarian and testicular components, size of the epididymis and testicular cords, number of ovarian follicles and testicular cords, uterus weight, and age index were analyzed statistically in a large sample of young and adult individuals of this species. Comparison of means and linear correlation analyses were done. Most variables were shown to be age dependent, with a period of rapid change during puberty. In adult animals, volume of the ovarian portion and uterus weight followed a seasonal cycle of sexual activity. Interindividual variability was evident in most of the variables investigated except for the number of testicular cords per ovotestis, which remained unchanged throughout the animal's life and hence was not inversely correlated with the number of ovarian follicles. This finding ruled out an ovary-testis transdifferentiation hypothesis for the ontogenic origin of the testicular tissue in the ovotestes of female moles. An alternative hypothesis based in the absence of oocytes in a portion of the undifferentiated fetal gonad is proposed in accordance with a new general model for mammalian sex determination.

Animals↗