Abstract：
:The structural and ultrastructural features of gonads from endemic Mexican fish have received scarce attention. This study describes the histological and ultrastructural characteristics of oocyte from Chirostoma humboldtianum. The ovary is asynchronic, and as such, most phases of oocyte development are found in the same ovary. The complete process of oogenesis was divided in five stages: oogonium and folliculogenesis, primary growth, cortical alveoli and lipid inclusions, vitellogenesis, and maturation. The presence of big filaments, which appear at the end of primary growth, induces some common follicular adaptation. During primary growth, abundant ribosomes, the rough endoplasmic reticulum, and mitochondria are grouped in the cytoplasm. At the end of this stage, the Z1 layer of the chorion is developed, while microvilli start to be evident. In the cortical alveoli and lipid droplets phase, intense PAS positive vesicles, some of them containing nucleoid material, are observed in the peripheral cytoplasm and the lipid droplets take a more central position. In vitellogenesis, the proteic yolk accumulates in a centripetal way while the chorion is completely formed. During maturation, the germinal vesicle migrates to the animal pole, meiosis is restored, and there is nuclear breakdown. The oocyte increases its size and holds some oil droplets and a big fluid mass of yolk. On the outside, filaments completely surround the oocyte.
journal_name
Rev Biol Tropjournal_title
Revista de biologia tropicalauthors
Cárdenas R,Chávez M,González JL,Aley P,Espinosa J,Jiménez-García LFsubject
Has Abstractpub_date
2008-09-01 00:00:00pages
1371-80issue
3eissn
0034-7744issn
2215-2075journal_volume
56pub_type
杂志文章abstract：:The sea urchin roe is among the highest valued seafood items in the world. Increasing demand has extended this fishery worldwide and cases of overfishing have been detected in some countries. On the eastern coast of Venezuela some species of sea urchin, such as Lytechinus variegatus, are consumed as food but studies t...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2000-12-01 00:00:00
abstract：:We summarize information concerning Recent and Pleistocene-Holocene Uruguayan sand dollars (Mellitidae), as well as Miocene taxa (Monophorasteridae). Recent and Pleistocene-Holocene species (Encope emarginata, Mellita quinquiesperforata, and Leodia sexisperforata) are at their southernmost limits of distribution, with...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2005-12-01 00:00:00
abstract：:Observations about the floral biology and the reproductive system of Macroptilium fraternum were made in two populations in Argentina, with different edaphic conditions, situated at the southern area of distribution of the species. The coexistence of two kind of flowers in the same plant was detected in both populatio...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2003-06-01 00:00:00
abstract：:The advancing agricultural frontier has led to an important loss of natural habitats, with significant consequences for biodiversity. The demography for two species of anurans, Physalaemus biligonigerus and Rhinella arenarum, both associated with agricultural systems in the central region of the C6rdoba Province, were...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2013-09-01 00:00:00
abstract：:Brycon henni, is a native fish from Western Colombia is important as food and in sport fishing, and could be cultured in waters between 18 and 28 degrees C. A previous cytogenetic study in branchial cells indicated different chromosomal complements. Total blood samples were seeded in 4 ml Ham-F12 culture medium, suppl...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2008-12-01 00:00:00
abstract：:Breast cancer is first in incidence and mortality among Costa Rican women. In 2011 there is a projected 1 071 new cases. We selected 116 patients diagnosed with breast cancer and family history of breast cancer. A detailed family history and epidemiology data was obtained from each patient and a blood sample was proce...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2012-12-01 00:00:00
abstract：:The diversity of chondrychthyans in Mexico is described. The fauna is composed by 214 species (111 sharks, 95 rays and 8 chimaeras) and represents 17.3 % of the total number of species recorded worldwide. The families with the highest diversity comprise: Rajidae (14.5 %), Carcharhinidae (12.1 %), Pentanchidae, Triakid...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2016-12-01 00:00:00
abstract：:A great extension (615,000 ha) of native savannas of the eastern plains of Venezuela have been replaced by plantations of Pinus caribaea var. hondurensis; however, only scarce information exists about the impact of this land use on carbon dynamics in soils. We studied the effect of temporal variability and the substit...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2008-12-01 00:00:00
abstract：:Pine plantations in the tropics are often employed to recondition eroded slopes from mudslides, as the Pinus caribaea plantation that shields the Universidad Simón Bolívar campus in Caracas (Venezuela). However, mismanagement of this plantation has led to its rapid degradation. The best option to maintain the protecti...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：10.15517/rbt.v64i2.19632
更新日期：2016-06-01 00:00:00
abstract：:The existence of monodominant forests on well-drained soils in tropical regions has been widely reported. Such forests most likely result from a combination of both ecological and evolutionary factors. Under conditions of high seed and seedling mortality, vegetative reproduction could create a reproductive advantage l...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：10.15517/rbt.v62i2.11639
更新日期：2014-06-01 00:00:00
abstract：:The vegetation of the sandy hills ("lomas") constitutes the main originality of the Peruvian and Chilean desert with a high number of endemics that shapes the vicarious associations. In this work, a phytosociological view of sandy environments of the Peruvian coastal desert is presented. According to the Braun-Blanque...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2011-06-01 00:00:00
abstract：:Bauxite explotation of the Orinoco River in recent years is an important source of heavy metals discharge in the ecosystem, changing the natural biochemical flow of these elements and their concentrations in water, sediment and organisms. Iron and copper concentrations were measured in the fish Plagioscion squamosissi...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2000-12-01 00:00:00
abstract：:One of the most important concepts in Panbiogeography is the generalized track, which represents an ancestral biota fragmented by geological events that can be recovered through several methods, including Parsimony analysis of endemicity (PAE) and endemicity analysis (EA). PAE has been frequently used to identify gene...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2016-12-01 00:00:00
abstract：:Coral reef status was surveyed in three south Pacific coral reefs of Costa Rica, one in Caño Island and two in Golfo Dulce, and the density, richness and distribution of non-colonial macro borers (> 1 mm) was determined in dead and live coral fragments from these reefs. Based upon traditional indicators of degradation...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：10.15517/rbt.v54i1.13977
更新日期：2006-03-01 00:00:00
abstract：:The euglossine bee Eulaema nigrita plays an important role for the pollination of native and economically important plants, such as the sweet passion-fruit Passiflora alata. E. nigrita uniquely collects the nectar from the flowers of P. alata, nevertheless, it needs to visit other plants to collect pollen, nectar and ...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：10.15517/rbt.v60i4.2073
更新日期：2012-12-01 00:00:00
abstract：:Dormirator maculatus (n=184) was collected in the Alvarado Lagoon, Mexico during a year period (Oct. 1993-1994). In the helminthologic review, the presence of Clinostomum complanatum (82.3%), Neoechinorhynchus golvani (76.1%), Spiroxys sp. (21.3 %), and Camallanus sp. (6.2%) was registered. Reduction of the hematocrit...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2004-06-01 00:00:00
abstract：:Cattleya trianae is an endemic species from the tropical rainforest in the Colombian Andes. Its survival is currently threatened due to habitat loss and commercial overexploitation. This study evaluates ten substrates, some organic (pine bark, coconut fiber and wood shavings), some inert icopor (polystyrene foam), veg...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：10.15517/rbt.v55i2.6045
更新日期：2007-06-01 00:00:00
abstract：:Resident and migratory shorebirds inhabit different kinds of wetlands such as lagoons, rivers and seashores among others. In recent years, these areas have been importantly affected by urban, agriculture and touristic activities, such as the Barra de Navidad lagoon, for which little information is available to support...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2012-09-01 00:00:00
abstract：:The local effects induced as a consequence of applications of four external secretions from the spider Sphaerobothria hoffmanni were recorded. Macroscopic lesions were not found; the only local effect microscopically observed was a weak necrosis in the skeletal muscle in mice. ...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：1984-11-01 00:00:00
abstract：:Occurrence of the bacterium Helicobacter pylori was compared for two Costa Rican sites with contrasting levels of gastric cancer incidence, Poás (incidence 15.13%) and Puriscal (83.53%). A sample of 185 adults of similar age and sex proportions was studied in each site, using both H. pylori antiserum tests and gastros...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：1998-09-01 00:00:00
abstract：:Most laboratory assessments of toxicity and bioaccumulation of heavy metals have been concentrated on the accumulation of these metal ions when exposed singly to the test organisms. However, under the natural environmental settings, the metals are never present in isolation and may interact with each other, therefore ...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：10.15517/rbt.v54i3.12791
更新日期：2006-09-01 00:00:00
abstract：:Deforestation of tropical forests is threatening monkey biodiversity and their health status, dependent of an ecologically undisturbed area. To asses this relationship, we analyzed parasite occurrence in their intestines. The study was conducted at the Estación Biológica La Suerte (EBLS), Limón, Costa Rica. The group ...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2010-12-01 00:00:00
abstract：:155 specimens of mussels (Modiolus capax) were gathered during March 1993 in a subtidal bed, located in northern Ocotal, Guanacaste, Costa Rica. For each individual in the random sample, shell length, breadth and height were measured and total weight, shell weight empty and meat weight were controlled. Analysis of dat...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：1995-04-01 00:00:00
abstract：:Limnocytherina is a genus conformed by 12 species; its distribution in the American continent is known to be exclusively on the North (neartics), but little is reported about its distribution from Mexico (transition zone) and Central America (Neotropics). Different sampling campaigns were undertaken in three crater la...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2014-03-01 00:00:00
abstract：:In Costa Rica, cervical cancer is the second most common female cancer, despite accessibility of screening through the universal health care system. There is little understanding of knowledge levels of the adolescent population on cervical cancer, although this population is the most exposed to risk factors. This stud...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：10.15517/rbt.v62i3.14063
更新日期：2014-09-01 00:00:00
abstract：:A new species of Hyalinobatrachium of the fleischmanni group, H. mondolfii, is described from the Orinoco delta floodplains in Venezuela. This new species can be distinguished from other congeners by the following combination of characters: parietal peritoneum clear, pericardium white, visceral and hepatic peritoneum ...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2001-09-01 00:00:00
abstract：:The marine phanerogam Syringodium filiforme, known as "manatee grass", is a common species that grows in coastal areas associated to Thalassia testudinum. With the aim to describe some of its possible chemical characteristics, this study was performed with a sample of 1.2 kg, collected in March 2009, in Guanabo beach,...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2011-03-01 00:00:00
abstract：:Centrostephanus coronatus reaches a density of 0.06 individuals/m2 in shallow reef waters in Parque Nacional Marino Ballena, Pacific of Costa Rica, in the same habitat occupied by the urchin Diadema mexicanum. It is the fourth species of diadematoid urchins reported for Costa Rican and a first new report for Central A...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2004-12-01 00:00:00
abstract：:Four sampling stations were set 200-500 m off Limon Port, Costa Rica, at an average depth of 20 m. From October 1996 to May 1997 horizontal subsuperficial trawls were done for 12 minutes at a speed of about 2 Km/h, with a 1,000 microns plancton net. A total of 28 samples were processed and 104 physical-chemistry param...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2000-06-01 00:00:00
abstract：:The need to propose recommendations for the management of over 80 species of bivalves and gastropod mollusks exploited commercially in Mexico, led to look for trends on the population and reproductive biology in relation to prevailing environmental conditions of the habitats where they are exploited. The reproductive ...
journal_title：Revista de biologia tropical
pub_type： 杂志文章
doi：
更新日期：2003-06-01 00:00:00
