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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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Nevertheless, the higher availability of different forbs and preferred shrubs as Acanthotippia vizccaha Ades- mia in rocky elevations is not accessible to vizcachas since they never visit this micro- habitat.

The consumption of Panicum changed from indifference to preference when or where its availability was very low. The immunoexpression of PRL increased in mid- and term pregnant groups, exhibiting in the latter the highest reactivity, especially in those lactotropic cells closest to the capillaries. Animals were grouped according to their xrespo status as the following: Biological Series of the Organization of American States, pp.

But what undoubtedly is the most outstanding aspect of its reproductive profile is the atypical gestational hormonal pattern characterized by the release of gonadotropin-releasing hormone GnRH followed by an LH surge around day of gestation. Neither tracks or faeces of vizcachas were found in the rocky elevations, even in those with vizcacheras at their foot. For the availability the two types of microhabitats PI: Different letters indicate significant differences.

IUCN Red List of Threatened Species

Melanin, a brownish-black pigment, is produced by the skin melanocytes which are derived from the neural crest and constitute the second most abundant cell in the epidermis [ 12 ]. Journal of Range Management, According to Branch et al.

Gestational stage was estimated by the time of capture and confirmed during the surgical procedure by the degree of fetal development as previously described [ 3237 ]. Click here to sign up. Identification of melanin in the bovine pineal gland.

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The experimental design was approved by vizcavha local ethics committee and was in agreement with the guidelines of the National Institute of Health NIH, USA for the use of experimental animals. Vizioli for his support during the collection of the data, E. In dog [ 17 ], cat [ 18 ], sheep [ 1920 ], bat [ 16 ], and bovine [ 12 ], significant differences were not reported.

International Journal of Endocrinology

Conflicts of Interest The authors declare that there is no conflict of interests regarding the publication of this paper. The authors wish to crfspo Mrs. The sections were examined using an Olympus BX light microscope. Daily morphological variations in the viscacha Lagostomus maximus maximus retina.

Labeling was assessed using an Olympus BX light microscope. So far, our attempts to determine circulating PRL levels either by 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. Even more, administration of P4 in the form of subcutaneous pellets rescues preimplantation embryo development and implantation in PRLR knockout females [ 53 ].

The inset shows the argentaffin reaction with greater detail. Image of female pineal gland in early pregnancy.

Samplings corresponded to winter Julyspring Octobersummer December and Februaryand autumn May. Proietto1,2 S. In fact, previous reports have shown that a LHR desensitization of credpo cells upon ligand-binding results in a decline in steady state levels of LHR mRNA [ 4647 ].

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Dietary selectivity within vizcaha plant category was estimated using the index proposed by Feinsinger et al. The photomicrograph shows a semithin section with numerous pigmented cells arrowheads in close relation to vvizcacha vessels v. Important goals for future studies are to evaluate: The perpendicular distance between the transect and each observed vizcachera was measured.

Under these conditions, the photoperiod and the retinal-pineal axis play an important role. The association between diet and availability compared the ri and ni frequencies by using the Spearman’s two-tailed rank correlation coefficient rs’ Siegel Each sample was obtained from a different vizcachera in July, December and May, and one composite sample for all vizcacheras in October and February.


Omission of the primary antibody did not reveal any staining in all examined sections. ccrespo

In Huayquerfas Coloradas plains, forbs were the only category showing a significant difference between availability and diet. Three levels of significance were considered in the statistical results, expressed as: Semithin section stained with toluidine blue exhibited numerous pigmented cells in close relation to blood vessels Figure 4.

Field and laboratory design Duringfive samplings were carried out in four 1O-km2 areas, represen- tative of the four above defined habitats. The irregular distribu- tion of volcanic stone outcrops has been pointed out as a determinant factor of spatial differences in vegetation and soil characteristics Mendez ; Gonzalez Diaz In order to establish the different groups, the time of capture was carefully planned according to the natural reproductive cycle of the vizcachas previously described by Llanos and Crespo [ 33 ] and also based on our own field expertise [ 28 — 3234 — 36 ].

The climate belongs to the continental desert type Consejo Federal de Inversiones The Masson-Fontana silver method for melanin resulted positive and the pigments manifested a strong argentaffin reaction. Pigments have been described in the pineal gland of different mammals such as bovines [ 1112 ], chinchilla [ 13 ], horse [ 14 ], bat [ 1516 ], dog [ 17 ], cat [ 18 ], sheep [ 1920 ], and humans [ 21 — 23 ].

This chamaephyte is preferred by guanaco Puig et ai. Materials and Methods 2. The blood was collected by cardiac puncture for the evaluation of serum hormone concentration. Enter the email address you signed up with and we’ll email you a reset link.

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 included.