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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Availability – Diet Fig. The distribution of vizcacha includes savannas, Monte scrubby areas and arid shrubby areas Olrog and Lucerorarely located higher than m Llanos and Crespo Bucher proposes that habitat modification by livestock grazing favours establishment of vizcachas. The pituitary PRL profile here characterized clearly has a different pattern than its ovarian receptor. The morphology of the mammal pineal gland presents great variability [ 193839 ].

Our analysis of LHR creapo in the ovary of vizcachas revealed an active transcription level at midpregnancy and in response to the LH surge.

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However, in the extracellular space, pigment granules were abundant and dispersed throughout the parenchyma, especially in mid and late pregnancy. A forced dietary selectivity was also detected in guanacos of La Payunia Puig et at. The microhabitat and the distance to the nearest rocky elevation were identi- fied for each observed vizcachera.

Cell types and blood vessels. A light and electron microscopic study of the pineal gland of the viscacha Lagostomus maximus maximus Journal of Pineal Research. The protective role of melanin against UV damage in human skin. Invitrogen, California, USA and used at a 1: Immunohistochemical scoring was determined using a 4-point scale: This is the first attempt to relate PRL as well as its ovarian receptor to some key steroidogenic markers involved vizcxcha the production of P4 during gestation of vizcachas.

Histochemical and ultrastructural studies of crespl pineal gland of female viscacha Lagostomus maximus maximus were performed to analyze the presence of pigmented cells under natural conditions and to evaluate a probable relation between pigment content and glandular activity during pregnancy. Identification cdespo melanin in the bovine pineal gland.

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Per field, the percentage of pigmented cells was obtained according to the following formula: Revista Argentina de Producci6n Animal, 6: Animals were housed for one week before euthanasia, under a Since the ovaries of the nonpregnant groups of this study LCT and NP exhibited almost the total absence of corpora lutea, the luteal immunoreactivity was analyzed only at the stages of pregnancy.

The pigment granules cresspo control slides were bleached by the treatment with potassium permanganate-acid oxalic and hydrogen peroxide, which identified the pigment histochemically as melanin. The high plant cover in the plains of Guadalosos, Huay- querfas Coloradas and Zaino, strongly dominated vizcqcha grasses Fig.

Estradiol and progesterone levels vary during pregnancy. This rise in LH leads to an ovulatory event that produces a great number of secondary corpora lutea with oocyte retention i.

In the present study, the histochemical and ultrastructural results demonstrate the presence of melanin in the female viscacha pineal gland. Author information Article notes Copyright and License information Disclaimer. Grisel Clausi Schettini and to Mister Santiago Cicculli for their technical assistance in tissue processing and confocal microscopy, respectively. 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 ].

This process alters their responsiveness to external signals allowing luteal cells to respond to a new set of hormones, the most important being PRL and LH [ 3 ]. Some authors have indicated the presence of a few retinal antigens in the pinealocytes [ 40 — 43 ].

InfoStat software version [ 37 ] was used for this analysis. We detected PRL immunoexpression in the pituitary gland pars distalis in all the experimental groups Figure 6. viczacha

Seasonal morphological variations and age-related changes of the seminal vesicle of viscacha Lagostomus Maximus Maximus: Consumption of chamae- phytes was higher in Escoriales, whose plains differed from the others due to the high chamaephytes availability.

No significant difference was detected among food-niche breadths from different habitats; sj.

This takes special relevance if we consider that for other rodents such as mice and rats, PRLR is a key component regulating ovarian function and governing the regulation of P4 secretion [ 22357 ]. The greatest amount of pigment crespk were identified in the pigmented cells.

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Corso1,2 P. The Australasian Journal of Dermatology. Postnatal development vicacha female sheep pineal gland under natural inhibitory photoperiods: Pregnant vizcachas were captured during cespo breeding season that lasts from April to August. PRLR immunoreactivity was weak at the beginning of pregnancy; it became markedly stronger at midgestation and decreased again near parturition time.

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The following techniques were applied: In short, if the luteal steroidogenesis of pregnant rcespo is, as we hypothesized, modulated in part by PRL, our results suggest that such regulation would be driven by the different vizcaca of PRLR expressed in the ovaries at each stage of pregnancy. Masson-Fontana silver method, counterstained with nuclear fast red. The broadening of vizcacha’s food niche when plant diversity increases could be explained as an adaptation to arid conditions Miller and Gaud Coarse grasses Stipa and Sporobolusthe forbs Solanum, Des- currainia and Erodium, the chamaephytes Hyalis and Baccharis, and the phanerophytes Lycium, Anarthrophyllum and Schinus tended to be avoided Table 1.

The climate belongs to the continental desert type Consejo Federal de Inversiones Daily morphological variations in the viscacha Lagostomus maximus maximus retina. The irregular distribu- tion of volcanic stone outcrops has been pointed out as a determinant factor of spatial differences cresop vegetation and soil characteristics Mendez ; Gonzalez Diaz E; Esco- rialesand food availability per microhabitat pI: Vrespo relative frequency of occurence of a species in the diet was detelmined for each sample by dividing the number of microscopic fields in which a given species occurred by the sum total of frequencies for all species identified Hole- chek and Gross Thus, the changes in the amount of pineal melanin seems to indicate a direct relationship between pigment content and gonadal hormone levels during pregnancy, when estradiol and progesterone levels remain elevated for a long time.

The diversities of plant species in the environment, as well as in the diet, were vizcafha using the standardized Shannon-Wiener function H’, Col- well and Futuymaand compared with the test of Hutcheson