Weir, "The reproductive physiology of the plains viscacha, Lagostomus maximus," Journal of Reproduction and Fertility, vol.
Weir, "The reproductive organs of the female plains viscacha, Lagostomus maximus," Journal of Reproduction and Fertility, vol.
Weir, "Implantation in the plains viscacha, Lagostomus maximus," Journal of Reproduction and Fertility, vol.
Adult female viscachas, weighing 2-4 kg, were captured in their habitat near San Luis, Argentina (33[degrees]20 south latitude, 769 m altitude).
In this research, 16 female viscachas (12 pregnant and 4 nonpregnant) were used.
The viscachas were quickly sacrificed by intracardiac injection of Euthanyle (0.25 ml/kg body weight, sodium pentobarbital, sodium diphenylhydantoin, Brouwer S.A.).
The pigmented cells were counted in pregnant and nonpregnant viscachas. For this purpose, four pineal glands per group were analyzed.
Variations in the amount of pineal pigments related to serum hormone levels were found between pregnant and nonpregnant viscachas. The pregnant ones presented a higher amount of pigments distributed within the parenchyma (Figure 5).
In contrast, the pigmented cells number varied significantly according to sex in viscacha. The pigments were exceptionally observed in adult and immature male viscachas [29].
Parameters Summer Autumn Winter Spring Heliophany (h) 9.38 7.09 6.82 9.09 Precipitation (mm) 90 27 11 58.5 Temperature ([degrees]C) 22 13 12 19.66 Table 2: Variations in the number of pigmented cells and serum hormone levels between nonpregnant and pregnant viscachas. Parameters Nonpregnant Early pregnancy Number of 0.76 [+ or -] 0.16 1.73 [+ or -] 0.18 (a) pigmented cells Estradiol (pg/ml) 18 [+ or -] 3.19 27.5 [+ or -] 2.5 Progesterone 0.72 [+ or -] 0.11 4.64 [+ or -] 0.95 (e) (ng/ml) Parameters Mid pregnancy Late pregnancy Number of 3.52 [+ or -] 0.35 (b) 2.58 [+ or -] 0.12 (c) pigmented cells Estradiol (pg/ml) 75 [+ or -] 2.89 (d) 24.25 [+ or -] 2.17 Progesterone 53.75 [+ or -] 2.39 (f) 18.61 [+ or -] 2.25 (g) (ng/ml) The values are expressed as mean [+ or -] SEM (n = 4).
The viscacha (Lagostomus maximus maximus), the largest member of the Chinchillidae family, inhabits the southern hemisphere from Paraguay through central Argentina [24].
The pineal gland of female viscacha presented an oval-like morphology, elongated, with a stalk connected to the brain.
In our laboratory, the morphology of the viscacha retinal melanosomes has been described [44].
In the present study, the histochemical and ultrastructural results demonstrate the presence of melanin in the female viscacha pineal gland.
In female viscacha, melanin granules within lysosome-like dense bodies were also observed.
