Plains viscacha were established in the laboratory to Spanish by Llanos & Crespo (), and some details of reproduction were given. Llanos, A. and J. Crespo. Ecología de la vizcacha (Lagostomus maximus maximus Blainv.) en el nordeste de la provincia de Entre Ríos. Rev. Llanos, A. C. and J. A. Crespo. Ecología de la vizcacha (Lagostomus maximus maximus Blainv.) en el nordeste de la Provincia de Entre Ríos. Revista de.

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Over forty years ago, Barbara Weir described particular aspects of the vizcwcha biology of female vizcachas that highlight this species among the majority of mammals [ 2526 ]. Considered as a generalist herbivore due to the high variety of plant species included in its diet, the vizcacha has shown a preference for grasses in semi- arid grasslands Giulietti and Jackson and scrublands Branch et at.

Five animals were tested per group. Skip to main content. A modified procedure for lead staining of thin sections. Regrettably, neither of these techniques proved to be successful for PRL serum determination in vizcachas.

P4 production is tied to the expression level of these two enzymes. Ovarian LHR mRNA level was significantly higher at midpregnancy, the reproductive stage characterized by the pseudoovulatory eventper group Figure 2 b. The South American plains vizcacha, Lagostomus maximus Rodentia: Abstract The presence of pigment has been demonstrated in different nervous structures such as those of retina, substantia nigraand locus coeruleus.

Previous reports have shown that Lagostomus maximus displays a peculiar P4 profile during gestation, which is characterized by two well-defined stages: The ultrastructure of the pigmented cells exhibited an ovoid or rounded nucleus in shape, with heterochromatin dispersed in the nuclear matrix. Morphometric Analysis The pigmented cells were counted in pregnant and nonpregnant viscachas.


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They exhibited a random distribution throughout the gland, but they were frequently found near blood vessels. Specialization on grasses could be attributed to the poor adaptation for ingesting shrubs, due to the fact that vizcachas were originally distributed along grasslands, and only secondarily co10nised shrubby areas Weir Omission of the primary antibody did not reveal any staining in all examined sections.

Conflicts of Interest The authors declare that there is no conflict of interests regarding the publication of this paper. In conclusion, we suggest that the pineal gland of female viscacha may be more susceptible to endocrine cues during vizcwcha and less subject to the environmental photoperiod, as in the case of the male viscacha.

Schmidt1,2 N. Vizcacha’s feeding behaviour does not agree with the Optimal Foraging Theory OFTwhich predicts a higher selectivity in situations of higher food diversity and abundance.

A more intensive feeding in the plains is justified by their higher plant cover, grasses proportion, and Panicum and Poa availabilities. The melanocyte and the epidermal melanin unit: To analyze pituitary PRL immunoreactivity, 3 slides with 3 adenohypophyseal sections per slide corresponding to rostral end, medial, and caudal end regions were tested 5 animals per experimental group.

IUCN Red List of Threatened Species

Discussion The morphology of the mammal pineal gland presents great variability [ 193839 ]. Vizcacha’s diet in La Payunia, within the most arid and elevated region of its distribution, showed a similar variety since half of the plant species present in the field were creso.


E; Esco- rialesand food availability per microhabitat pI: However, the biological significance of these pigments in the pineal gland has not yet been established. The gestation period lasts approximately days, and it ends in spring when the mother and offsprings have greater probabilities of survival [ 26 ].

Number of pigmented cells: Une forte selectivite s’exprime dans les habitats et au cours vizcaca saisons a faible diversite vegetale. For each section, 10 microscopic fields were randomly selected throughout the pineal gland.

The first step in the path of P4 biosynthesis is performed by the cytochrome P side-chain crespp Psccwhich converts cholesterol into pregnenolone.

In the pinealocytes, the melanosomes were often found within lysosome-like dense bodies Figure 6 b. International Journal vizxacha Endocrinology. The reproductive physiology of the plains viscacha, Lagostomus maximus.

Di Giorgio et al. Image of female pineal gland in mid pregnancy. The pigments were exceptionally observed in adult and immature male viscachas [ 29 ]. Intra- and interassay coefficients of variation were 7. So far, our attempts to determine circulating PRL levels either creepo RIA or by ELISA did not yield positive results probably due to a subject linked to the specificity of the antibodies used in both techniques.

Some authors have indicated the presence of a few retinal antigens in the pinealocytes [ 40 — 43 ]. Invitrogen, California, USA and used at a 1: Different letters indicate significant differences.