Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ARTIODACTYLA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,099 records · Page 61Linked to original sources
PubMed1989

In situ morphologic dynamics of ovaries, uterus, and cervix in llamas.

The morphologic appearance of the ovaries, uterus, and cervix of nonpregnant and pregnant (less than 50 days) llamas (n = 21) were monitored daily by transrectal ultrasonography, and uterine tone was monitored by transrectal digital palpation. Follicle size and the presence or absence of corpora lutea were recorded and related to changes in morphology of uterus and cervix. Emphasis was given to the dynamics of curling of uterine horns and changes in uterine tone. For statistical purposes, uterine and cervical characteristics were scored 1 to 4 (minimal to maximal). Data were placed into 1 of the following reproductive statuses: 1) follicular dominance, 2) luteal dominance, and 3) pregnancy. Follicles were characteristically arranged along the periphery of the ovary, and large follicles and the corpus luteum protruded distinctly from the ovarian surface. The preovulatory follicle grew at a mean rate of 0.7 mm/day and the average diameter on the day before ovulation was 10.6 +/- 0.9 mm. Ovulation (Day 0) was detected an average of 1.8 days after a single mating. The mature corpus luteum was 11-13 mm in diameter and was characteristically hypoechogenic with a white (echogenic) horizontal area in the center. Pregnancy was detected as early as 11 days post-mating and all (7/7) singleton embryonic vesicles were detected in the left uterine horn. Uterine and cervical echotexture was darker (p less than 0.01) during follicular dominance than during luteal dominance and pregnancy, indicating a decrease in tissue interfaces or an increase in intercellular fluid during follicular dominance. The cervical folds became echogenic and prominent during luteal dominance.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Hormonal regulation of uterine secretion of prostaglandin F2 alpha during luteolysis in ruminants.

In recent years, considerable progress has been made in our understanding of the endocrine mechanisms that control the pattern and timing of uterine secretion of prostaglandin F2 alpha (PGF2 alpha) during luteolysis in ruminants. Oxytocin may be important in establishing a pulsatile pattern of secretion. Neurohypophyseal oxytocin appears to be released in a pulsatile fashion and may initiate each episode of PGF2 alpha secretion from the uterus. Uterine PGF2 alpha stimulates release of oxytocin from the corpus luteum. Luteal oxytocin further stimulates secretion of PGF2 alpha from the uterus and may induce a transient refractoriness of the uterus to subsequent stimulation with oxytocin. Uterine refractoriness subsides after approximately 6 h. A similar desensitization phenomenon occurs in response to PGF2 alpha at the level of the corpus luteum. Together, uterine and luteal refractoriness may account for the interval between pulses of PGF2 alpha observed during luteolysis. Uterine secretory responsiveness to oxytocin increases at luteolysis, when endogenous, pulsatile secretion of PGF2 alpha normally begins. Thus, the acquisition by the uterus of responsiveness to oxytocin may determine when endogenous secretion of PGF2 alpha occurs during the estrous cycle. Uterine secretory responsiveness to oxytocin develops slowly, in the presence of progesterone. Progesterone exerts two types of effects that contribute to the regulation of PGF2 alpha secretion. First, prolonged exposure to progesterone appears to promote uterine accumulation of arachidonic acid, prostaglandin endoperoxide synthase, and other substances needed for synthesis of PGF2 alpha. Second, progesterone exerts a suppressive effect on secretion, which wanes after prolonged exposure. Together, these effects of progesterone ensure that PGF2 alpha is secreted only at the appropriate time to induce luteolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Giant verrucous carcinoma in a giraffe.

An 18-year-old male giraffe developed a verrucous lesion, 50 cm in diameter, on a flank. Some areas of the lesion were histologically typical of a viral verruca with papillomatosis, prominent hypergranulosis, and inclusion bodies. The bulk of the mass was a well-differentiated verrucous type of squamous cell carcinoma. It may be that the virus of the verruca also caused the verrucous carcinoma.

Animals↗
PubMed1994

Spontaneously occurring fractures of the spine in skeletally immature animals.

STUDY DESIGN: Twelve spontaneously occurring fractures of the spin in nine skeletally immature animals were investigated. OBJECTIVES: These fractures were analyzed radiographically, morphologically, and histologically. SUMMARY OF BACKGROUND DATA: The most commonly injured regions were the cervical and lumbar regions. Multiple-level fractures were noted in three specimens. METHODS: Morphologic and histologic examination invariably detected fractures in cases of spinal cord injury without radiographic abnormality. RESULTS: The end-plate physes and synchondroses were found to be the "weak links" for propagation of fractures. Radiographically benign-appearing ring apophyseal fractures were found histologically to propagate from the end-plate physis through the vertebral body via the contiguous neurocentral synchondroses. CONCLUSIONS: The observed morphologic and histologic fracture patterns should provide a better understanding of the probable comparable pathoanatomy of spine and spinal cord injuries in children.

Animals↗
PubMed1994

The adaptive significance of reproductive strategies in ungulates.

We examine the relation between litter size, gestation length, neonate mass and growth rate among ungulates. By using a recent method for analysing comparative data, we show that ungulates can be divided along a slow-fast continuum, even after accounting for the effects of maternal body mass and common ancestry. Some species produce many small offspring during a short period, whereas others take a long time to raise a single large offspring. These differences in life-history strategy are associated with diet, i.e. browsers have relatively larger litters and smaller neonates than grazers.

Adaptation, Physiological↗
PubMed2002

A covarion-based method for detecting molecular adaptation: application to the evolution of primate mitochondrial genomes.

A new method for detecting site-specific variation of evolutionary rate (the so-called covarion process) from protein sequence data is proposed. It involves comparing the maximum-likelihood estimates of the replacement rate of an amino acid site in distinct subtrees of a large tree. This approach allows detection of covarion at the gene or the amino acid levels. The method is applied to mammalian-mitochondrial-protein sequences. Significant covarion-like evolution is found in the (simian) primate lineage: some amino acid positions are fast-evolving (i.e. unconstrained) in non-primate mammals but slow-evolving (i.e. highly constrained) in primates, and some show the opposite pattern. Our results indicate that the mitochondrial genome of primates reached a new peak of the adaptive landscape through positive selection.

Animals↗
PubMed2006

Both social and ecological factors predict ungulate brain size.

Among mammals, the members of some Orders have relatively large brains. Alternative explanations for this have emphasized either social or ecological selection pressures favouring greater information-processing capacities, including large group size, greater foraging efficiency, higher innovation rates, better invasion success and complex problem solving. However, the focal taxa for these analyses (primates, carnivores and birds) often show both varied ecological competence and social complexity. Here, we focus on the specific relationship between social complexity and brain size in ungulates, a group with relatively simple patterns of resource use, but extremely varied social behaviours. The statistical approach we used, phylogenetic generalized least squares, showed that relative brain size was independently associated with sociality and social complexity as well as with habitat use, while relative neocortex size is associated with social but not ecological factors. A simple index of sociality was a better predictor of both total brain and neocortex size than group size, which may indicate that the cognitive demands of sociality depend on the nature of social relationships as well as the total number of individuals in a group.

Animals↗
PubMed1981

Soil as the source of trace elements.

The nature of the parent rock determines the trace element content of soils. Ultrabasic and basic rocks, which solidified first from the molten magma, incorporated bioessential trace elements such as Co, Ni, Zn and Cr by isomorphous replacement of Fe and Mg in ferromagnesian minerals, while acidic rocks, the last to solidify, tended to be richer in other elements such as Ba and Pb. Cu, Mn and, to a lesser extent, B, Mo and Se are more evenly distributed. The weathering of rocks by pedological and biological processes such as glacial and hydrodynamic comminution, secretion of acids and liganding species by microbes and plants leads to the formation of sands, silts and clays, and finally the incorporation of organic matter causes humification and the formation of soils as we know them. Part of the soil's store of bioessential elements is held in forms that are available to plants. Availability is controlled by the forms of occurrence and the nature of binding of the trace elements in the soil, which in turn is affected by soil acidity, redox balance (drainage) and organic matter content. These and other factors are discussed along with measures for alleviation of deficiency problems. Future progress in this area will depend to a large extent on interdisciplinary research by biologists, chemists, physicists and statisticians.

Agriculture↗
PubMed1981

An appraisal of the newer trace elements.

For an element to be considered essential it should satisfy three criteria: (1) it must be present in living matter; (2) it must be able to interact with living systems; (3) a dietary deficiency must consistently result in a reduction of a biological function, preventable or reversible by physiological amounts of the element. Ideally, essentiality should be established in more than one species and confirmed in more than one laboratory. Since 1970, vanadium, fluorine, silicon, nickel and arsenic have been shown to meet all the criteria listed above, and evidence from one laboratory has indicated that tin may have an essential biological role in the laboratory rat. A review is presented of the evidence on which the essentiality of these elements has been established and, when known, an indication of their biochemical functions. The possible significance of these 'newer' trace elements to the health of man and animals is discussed.

Animal Nutritional Physiological Phenomena↗