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At least 37 records · Page 2Linked to original sources
PubMed1978

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↗
PubMed1978

Arteriovenous anastomoses in the skin of seals. II. The California sea lion Zalophus californianus and the northern fur seal Callorhinus ursinus (Pinnipedia: Otariidae).

The structure, distribution and density of arteriovenous anastomoses (AVAs) were studied in body and flipper skin of a California sea lion and a nothern fur seal. In both animals AVAs consisted of arterial, intermediate and venous segments, and were generally larger and more tortuous in the sea lion than in the fur seal. In the sea lion the majority of AVAs (72%) occurred in the deeper region of the dermis, and the density was significantly greater in the flippers than in the body. In the northern fur seal most AVAs (76%) occurred in the superficial region of the dermis; the density of AVAs in flipper skin was significantly higher than in body skin, and the density in the hind flipper was significantly greater than in the foreflipper. Arteriovenous anastomoses are important in the regulation of body temperature in seals; when these animals are on land, AVAs function to dissipate body heat, and vascular thermoregulation occurs in the flippers but notover the general body surface. Due to differences in distribution and density, AVAs play a more significant role in thermoregulation in the northern fur seal than in the California sea lion.

Animals↗
PubMed1981

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↗
PubMed1983

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↗
PubMed2005

Gas chromatographic quantification of free D-amino acids in higher vertebrates.

D-amino acids were determined in brain, body fluids (urine, blood coagulate, serum, plasma) and faeces of animals belonging to nine out of 11 taxonomic orders of vertebrates (Artiodactyla, Aves, Carnivora, Lagomorpha, Marsupalia, Osteichthyes, Primates, Rodentia, Tubilidentata). Free amino acids were isolated by means of cation exchangers and converted into volatile N(O)-perfluoroacylamino acid propyl esters. Derivatives of amino acids were separated into D- and L-enantiomers using Chirasil-L-Val capillary columns and detected by selected ion monitoring mass spectrometry. Quantification of amino acids was achieved by comparison of analytes with amino acid standards using L-norleucine as internal standard. Large relative amounts of D-serine were determined in brains of mammals but not of birds. In body fluids the D-enantiomers of most proteinogenic L-amino acids were detected, largest absolute and relative amounts were found in urine. Therein quantities of D-Ala and D-Ser exceeded 50% relative to the L-enantiomers in many instances. Feeding animals with diet fortified with DL-Met resulted in excretion of almost racemic Met in urine. D-Amino acids were also abundant in faeces of rodents. The data confirm that d-amino acids are common in body fluids and certain tissues of vertebrates.

Amino Acids↗
PubMed1976

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↗
PubMed1975

Some anatomical aspects of the cardiovascular system of Antarctic seals and their possible functional significance in diving.

The hearts and ascending aortae of 11 Weddell seals, Leptonychotes weddelli, three adult Crabeater seals, Lobodon carcinophagus, two adult Ross seals, Ommatophoca rossi, and one adult Leopard seal, Hydrurga leptonyx, were examined for comparison with terrestrial forms. The Weddell seal specimens were from animals ranging in age from midterm in fetal development to mature adults. All specimens were collected in 1971, 1972, and 1973, from McMurdo Sound and the Ross Sea, Antarctica. The phocid hearts were characteristically broader and flatter than those of other carnivore families and they tended toward bifid apices. The heart form indices (height/circumference) averaged 31.5 compared to 39.0 for felids. The right ventricular chambers of the Antarctic seals were found to average longer in Weddells and narrower in all, than those reported for four other carnivore families. An elastic enlargement was present in the ascending aortae of all seals. The largest diameter of the aortic bulb averaged 25.5 mm more than the base of the aorta in the adult Weddell seals which represented an increase of 72.5% over the base. It is suggested that the general heart form, and especially the ascending aortae, are anatomical adaptations to diving. The compressed heart makes possible unimpaired function when the chest is compressed during deep dives. The aortic bulb maintains mean arterial blood pressure and perfusion of the brain and cardiac tissue during diving bradycardia.

Adaptation, Physiological↗