The sphincter above the diaphragm on the inferior vena cava of the common seal (Phoca vitulina L.).
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Animals↗
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CORPORATE seals; some new designs for the National Health Service.
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Animals↗
Histological, histochemical, and fine structural observations on the lymph node of the common seal (Phoca vitulina) and the grey seal (Halichoerus grypus).
BACKGROUND: The recent seal death epizootic prompted interest in their immune system, for which no current morphological data were available. METHODS: Lymph nodes from adult harbor seals (Phoca vitulina) and grey seals (Halichoerus grypus) were investigated by light microscopy, electron microscopy, and lectin histochemistry. RESULTS: No significant differences in the lymph node morphology were found between the two species, and the overall organization of the nodes comprises of capsule, trabeculae, cortex, paracortex, and medulla. Capsule and trabeculae are composed of tightly packed collagen and elastic fibrils and are rich in fibroblasts, myofibroblasts, and smooth muscle cells. Unmyelinated nerve fibers are common. The cortex contains numerous secondary follicles with well-developed germinal centers and paracortical areas with high endothelial venules. Antigen-presenting cells and phagocytic macrophages were abundantly present. The medullary cords contain numerous plasma cells. Fibroblastic reticulum cells are common throughout the parenchyma and transverse the sinus. Marginal, radial, and medullary sinuses are lined by littoral cells. The visceral lining of the sinuses is marked by macrophages and by numerous mast cells. CONCLUSIONS: The morphology of seal lymph nodes does not differ significantly from that of terrestrial mammals. Earlier functional conclusions concerning seal lymph nodes are substantiated by this morphological study.
Animals↗
Histophysiological observations on the external auditory meatus, middle, and inner ear of the Weddell seal (Leptonychotes weddelli).
The external auditory meatus, middle, and inner ear of the deep-diving Weddell seal (Leptonychotes weddelli) were studied with light microscopic, histological, and histochemical techniques in order to contribute to the open discussion on the orientation of this seal in the darkness of the deep Antarctic seas. The external auditory meatus is characterized by a well-developed venous plexus, single apocrine ceruminous, and numerous holocrine sebaceous glands and an incomplete tube of elastic cartilage. The tympanic membrane is comprised of two layers of radially and concentrically arranged collagen fibers and by elastic fibers which are concentrated in the outer part of the ear drum. The tympanic cavity is lined by a pseudostratified prismatic ciliated epithelium with goblet cells; a plexus of wide venous vessels marks the subepithelial lamina propria. The cochlea is about 10 mm high and forms about two and a half turns. The richly pigmented stria vascularis is well vascularized, while the cell-rich prominentia spiralis contains only single small blood vessels. The organ of Corti contains one row of inner and three rows of outer hair cells. Cells of Hensen, Claudius, and Boettcher are present. The basilar membrane is of comparatively uniform simple structure and is composed of abundant glycoproteins, proteoglycans, collagenous fibers, and the loose tissue of the tympanal layer. The spiral ligament is built up by abundant proteoglycans and a complex system of radial and concentric collagen fibers; close to the osseous wall of the bony cochlea it contains fine elastic fibers. The inner zone of the osseous wall of the cochlea strikingly contains hyaline cartilage. The thin lamina spiralis ossea is covered by a limbus spiralis with interdental cells secreting the lamina tectoria, which has a fibrous texture and contains glycoproteins and negatively charged components.
Adaptation, Physiological↗
Nonaqueous electrochromatography on C30 columns: separation of retinyl esters.
A nonaqueous packed capillary electrochromatographic reversed-phase method for separation of retinyl esters has been developed. The retinyl esters all-trans-retinyl acetate, palmitate, heptadecanoate, stearate, oleoate, and linoleoate were separated on a 180 microm ID column packed with 5 microm C30 particles with a mobile phase consisting of 2.5 mM lithium acetate in N,N-dimethylformamide-methanol (99:1, v/v). With this mobile phase, the electroosmotic flow was 0.8 mm/s at 650 V/cm and 40 degrees C, and the separation was completed in less than 30 min on 30 cm columns. To obtain electrostable frits of the hydrophobic C30 material both the preparation of the frits and the conditioning of the column prior to electroconditioning were of importance. Selectivity changes were introduced by replacing up to 70% v/v of the N,N-dimethylformamide by acetonitrile. The increase in the amount of acetonitrile was, however, accompanied by a significant increase in analysis time. Liver extracts obtained from arctic seal were analyzed.
Animals↗
Evidence of saxitoxin derivatives as causative agents in the 1997 mass mortality of monk seals in the Cape Blanc Peninsula.
Monk seals in Cape Blanc (Western Sahara coast) suffered a mass mortality during May-July 1997 which was attributed to a morbillivirus. High performance liquid chromatography (HPLC) analysis on tissues of seals killed during the outbreak and on related fauna showed peaks with retention times coincident with those of some saxitoxin derivatives but their identity was not proved. Here we present results of further HPLC analyses that unambiguously prove the identity of these toxins by mass spectrometry (MS), supporting the hypothesis that this mortality of monk seals was caused by biotoxins rather than by a morbillivirus.
Africa↗
Specializations in the skin of the seal (Phoca vitulina).
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Animals↗
Ultrastructure of the placenta of Antarctic seals during the first third of pregnancy.
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Animals↗
Dimensional analysis and dynamic response characterization of mammalian peripheral vestibular structures.
Extensive morphometric measurements were made on the vestibular system of the rabbit ( Oryctulagus cuniculus), the gerbil (Meriones unguiculatus), the chinchilla (Chinchilla laniger ), and the squirrel monkey (Saimiri sciureus) from serial sections of temporal bones. Additionally, a more limited set of measurements were also completed on the owl monkey (Aotus trivirgatus), the Capuchin monkey (Cebus sp.), the harp seal ( Pagophilus groenlandicus Erxleben , 1777), and the two-toed sloth ( Choloepus sp.). The following measurements were made: 1) radius of curvature (R) of each membranous semicircular canal (herein called semicircular duct-see nomenclature in Nomina Anatomica (1968) ), 2) cross-sectional diameter of the ducts and the osseous semicircular canals, and 3) some pertinent morphometrics of the cristae ampullares and the utricle. In all species studied 1) the radii of curvature of the three semicircular ducts are dissimilar, with that of the lateral duct being as small as, or smaller than, those of the anterior and posterior ducts; 2) R for the anterior duct is largest in the harp seal and the rabbit; 3) the canal and duct dimensions are largest in the Capuchin and squirrel monkeys, the two-toed sloth, and the harp seal, and smallest in the gerbil; 4) the proportion of otic fluid "space" that is occupied by endolymph shows a ranking of gerbil greater than rabbit greater than two-toed sloth greater than chinchilla = owl monkey greater than squirrel monkey greater than Capuchin monkey greater than harp seal; and 5) the gross ampullary and utricular dimensions are largest in the harp seal and smallest in the gerbil. These measurements were used for determining the time constants describing semicircular-canal dynamics in the Steinhausen (1931, 1933) and Oman -Marcus (1980) equations.
Animals↗
Adenohypophysis of the elephant seal (Mirounga leonina): morphology and seasonal histological changes.
Changes in adenohypophyseal cell populations over a 12-month period were studied in the seasonally breeding elephant seal (24 adult males, 3 adult females, and 5 neonates) at Macquarie Island. The glands were weighed and fixed in formol sublimate. Selected sections were stained with the oxidation-alcian blue-periodic acid Schiff-orange G technique. Gonadotropic, thyrotropic, lactotropic, and somatotropic cells were readily identifiable; whilst corticotropes, inactive secretory cells of all types, and stellate cells were not stained and were counted collectively as chromophobic cells. Hypophyseal weight was low throughout autumn and winter, but increased significantly during the spring breeding season and the summer. Thyrotropes were distributed evenly throughout the pars distalis, but the other secretory cells showed areas of concentration. Acidophils were common peripherally, particularly lactotropes, while gonadotropes were largely confined to the 'basophilic wedge,' a narrow, central superior zone. In males, lactotropic and gonadotropic cells showed significant seasonal changes in number. Gonadotropes were more common in sexually active males than sexually quiescent ones, while lactotrope numbers were much greater at midsummer than midwinter. This lactotrope cycle appeared to be related to photoperiod but unrelated to breeding.
Animals↗
Histological, histochemical, and fine structural observations on the spleen of seals.
Spleens of three species of Antarctic seals with different diving habits (Weddell seal, crabeater seal, and fur seal) have been studied with histological, histochemical, and electron microscopic methods. The spleens can be classified as nonsinusoidal, with capsule and trabeculae rich in innervated smooth muscle cells. The trabecular system is particularly well developed in the deep- and long-diving Weddell seal. As in other mammals the pulp can be divided into white and red pulp. In the white pulp, periarteriolar lymphatic sheaths and secondary lymphatic nodules occur; both are surrounded by a marginal zone rich in macrophages and eosinophils. The nodules can be observed frequently, which is in accordance with abundance of plasma cells in the red pulp. Well-developed white pulp and numerous plasma cells and eosinophils obviously reflect a high load of nematodes, which have mainly been found in lung and stomach. Additionally, in the red pulp morphological evidence for the following functions has been found: destruction of erythrocytes, erythropoiesis, and thrombopoiesis. In respect to blood flow through the red pulp, we interpret our observations in the following way: terminal branches of arterioles open into the space between the fibroblastic reticulum cells; blood draining from here is collected into pulp veins, which are mainly found near the trabeculae. Thus, the seals have an open vascular compartment in their spleens, as also occurs in the cat. The red pulp is innervated by numerous nerve fibers that seem to include both cholinergic and adrenergic ones. The target cells of these fibers seem to be the fibroblastic reticulum cells, whose state of contraction may influence the direction of blood flow through the red pulp.
Animals↗
Arteriovenous anastomoses in the skin of seals. I. The Weddell seal Leptonychotes weddelli and the elephant seal Mirounga leonina (Pinnipedia: Phocidae).
The structure, distribution, density and innervation of arteriovenous anastomoses (AVAs) have been compared in the skin of Weddell and elephant seals, as part of a study of the structure and function of arteriovenous anastomoses in mammals. In both genera AVAs were coiled vessels with the segmental structure typical of "epithelioid" anastomoses and possessed a dense peripheral adrenergic innervation. In both Weddell and elephant seals there was no statistically significant difference between the mean density of AVAs in body skin and flipper skin. The majority, approximately 71% of AVAs occurred superficially in the dermis, fewer (23%) occurred in the deeper dermis, and 6% were present in the thick hypodermis (bubber). The density of AVAs in Weddell and elephant seals is approximately eight times greater than that reported in other animals and the superficial position of anastomoses over the whole of the body surface is characteristic of phocid seals. When open, AVAs in Weddell and elephant seals allow maximal heat loss from the skin surface by passing large volumes of blood into the superficial veins. AVAs in seals are important in dissipation of body heat, particularly when the animals are out of the water, and the entire surface area is thermoregulatory rather than specific regions such as the flippers.
Animals↗
The mammary gland of the Weddell seal, Leptonychotes weddelli (Pinnipedia). I. Gross and microscopic anatomy.
The Weddell seal cow possesses two subcutaneous, ellipsoidal, abdominal mammary glands with a volume of two to three liters when lactating. Corrosion casts reveal that approximately ten large ducts radiate from a gland cistern at the base of the nipple, and end in a complex system of terminal branches. Each gland has a separate arterial supply, mostly from the caudal deep epigastric with a minor contribution from the deep circumflex iliac. Histologically, lactating, nonlactating (resting), and immature glands resemble those of other eutherians. Sinusoidal blood vessels, not observed in the mammary glands of other mammals, are present within lactating but not in resting lobules in the seal. The terminal pouch and lactiferous sinuses possess circular smooth muscle and elastic fibers in the walls, and accumulations of lymphocytes immediately beneath the epithelium. Sebaceous and sweat glands open into the walls of the nipple and the apex of the terminal pouch. There are extensive networks of blood vessels and longitudinal smooth muscle and elastic fibers in the walls and base of the nipple. The possible functions of these morphological observations are discussed.
Animals↗
Distribution and size of Boettcher cells in the little brown bat, rabbit, and other species.
The distribution and size of Boettcher cells were determined from serial sections of the temporal bones of four little brown bats and six rabbits. In addition, one harp seal and one two-toed sloth were examined. In the little brown bat, the heights of the Boettcher cells measured 4-8 micron and they were found throughout much of the length of the cochlea. There were four rows in most of the lower basal coil, five rows in the upper basal coil, and four rows in the middle coil. In the rabbit there were nine rows in the basal coil and 12 rows in the middle coil. The heights of the Boettcher cells were approximately 14 micron in the rabbit. In the two-toed sloth, Boettcher cells were sparsely distributed along the basal coil; similarly, in the harp seal, Boettcher cells were confined solely to the basal coil, where there were only three rows, which measured approximately 18 micron in height. The distribution and size of Boettcher cells in the rabbit and the little brown bat were compared to those in other mammalian species.
Animals↗
Venous structures associated with thermoregulation of phocid seal reproductive organs.
BACKGROUND: Seal reproductive systems are surrounded by thermogenic muscle and insulating blubber, suggesting elevated temperatures at the gonads and uterus. In the limbs of terrestrial mammals, cooled blood returning from superficial veins is mixed proximally with warm blood returning from deep veins. Thus, mixed cool-superficial and warm-deep venous blood from the hind limbs is returned to the central circulation. METHODS: We describe structures observed in salvaged carcasses of harbor (Phoca vitulina), gray (Haliochoerus gryphus), harp (Phoca groendlandica), hooded (Cystophora cristata), and ringed (Phoca hispida) seals. Vessels were identified by dissection of injected and uninjected material. RESULTS: In contrast to terrestrial mammals, phocid seals have anastomoses between the veins of the distal hind limb and the pelvis which allow large volumes of cool blood returning from the skin surface of the flipper to enter the gluteal, pelvic, or pudendo-epigastric veins. This provides a cool-superficial venous return that remains separate from the warm-deep venous return of the femoral veins. The cooled venous blood from the hind flippers supplies venous plexuses lining the inguinal region and the abdominal and pelvic cavities. CONCLUSIONS: Cooled blood may prevent hyperthermic insult to seal reproductive systems.
Abdomen↗
Microstructure and innervation of the mystacial vibrissal follicle-sinus complex in bearded seals, Erignathus barbatus (Pinnipedia: Phocidae).
Vibrissal follicle-sinus complexes (F-SCs) are sensory receptors of the mammalian integument system. They are best developed within Pinnipedia. The objective of this study was to investigate the F-SCs of bearded seals (Erignathus barbatus) for benthic foraging adaptations. Bearded seals possessed approximately 244 mystacial F-SCs. In this species, F-SCs consisted of an outer dermal capsule (DC) surrounding a blood sinus system [upper cavernous sinus (UCS), ring sinus (RS), and lower cavernous sinus (LCS)] and concentric rings of epidermal tissue. The UCS comprised up to 62% of the F-SC length and may function as thermal protection for mechanoreceptors. A large asymmetrical ringwulst was located in the RS. A deep vibrissal nerve penetrated the DC at its base and terminated on mechanoreceptors in the epidermal tissues of the LCS and RS. The mean number of myelinated axons per F-SC was 1,314 (range, 811-1,650) and was among the highest number of axons per F-SC reported to date. An estimated mean number of 320,616 myelinated axons innervate the entire mystacial vibrissal array. Merkel-Neurite complexes (MNCs) and small simple laminated corpuscles were found in the region of the LCS. Myelinated axons also terminated on MNCs and lanceolate endings apical to the ringwulst. The number of F-SCs, their geometry in the mystacial region, the number of myelinated axons per F-SC, and the distribution of mechanoreceptors support the premise that pinniped vibrissae are sensitive active-touch receptor systems, and that structural differences in bearded seals, relative to other phocids, may be adaptations for benthic foraging.
Animals↗
Enantioselective and nonenantioselective degradation of organic pollutants in the marine ecosystem.
Enantiomeric ratios of 11 chiral environmental pollutants determined in different compartments of the marine ecosystem by chiral capillary gas chromatography and chiral high-performance liquid chromatography allow discrimination between the following processes: enantioselective decomposition of both enantiomers with different velocities by marine microorganisms (alpha-HCH, beta-PCCH, gamma-PCCH); enantioselective decomposition of one enantiomer only by marine microorganisms (DCPP); enantioselective decomposition by enzymatic processes in marine biota (alpha-HCH, beta-PCCH, trans-chlordane, cis-chlordane, octachlordane MC4, octachlordane MC5, octachlordane MC7, oxychlordane, heptachlor epoxide); enantioselective active transport through the "blood-brain barrier" (alpha-HCH); nonenantioselective photochemical degradation (alpha-HCH, beta-PCCH).
Adipose Tissue↗
Visual evoked response (VER) changes during maturation in the Weddell seal.
Visual evoked responses (VER'S) were recorded from the cortex of immature Weddel seals, 3-365 days of age. Results indicated a high degree of maturity at birth evident from the multiphasic array of waveforms and the comparatively short onset latency of the VER. At low intensities, single flashes evoked an immature secondary response. Topographical distribution of VER's were confined largely to the gyrus immediately adjacent to midline, from the posterior aspect near lambda to the vertex. Recordings from CI-744 dosed seals displayed a well-demarcated developmental sequence of VER's, contrary to VER's recorded in flaxedilized seals. Onset latency and waveform configuration changed concomitantly as a function of age. During the postnatal period from birth to weaning, VER changes were related to major behavioral events such as the seal's first encounter with swimming and diving at 2 weeks of age and weaning at 6 weeks of age.
Age Factors↗