Sexual dimorphism in the whole brain and brainstem morphometry in the African giant pouched rat (Cricetomys gambianus, Waterhouse 1840)

The study was conducted to evaluate the sexual dimorphism in the morphometric parameters of the whole brain and the brainstem in adult captive African giant pouched rats. Twenty-nine brain samples, comprising 15 females and 14 males, were utilized. Following brain extraction by standard procedures, the mean values of the weights, lengths, diameters, and volumes of the intact brains and the brainstem structures were compared in male and female rats using quantitative analytical statistical methods. The absolute brain weight obtained in the male was significantly higher (p < 0.01) than that of the female while the relative brain weight obtained in the female (0.636 &#177; 0.049%) was higher than that of the male rats (0.564 &#177; 0.032%), although the difference in the values was not statistically significant (p > 0.05). The lengths of the brain and myelencephalon, as well as the weights of the myelencephalon and mesencephalon, did not differ between the two sexes (p > 0.05). The weights and lengths of the pons did not differ between the two sexes (p > 0.05). There was a significant difference (p < 0.05) in the pyramidal length and a highly significant difference (p < 0.01) in the pyramidal width between the two sexes, with the male rats having higher values. This pioneering sexual dimorphic brain morphometry provides information for further research. (Folia Morphol 2010; 69, 2: 69-74

Effects of continuous light exposure on testicular structure and function of the African giant rat (Cricetomys gambianus)

The aim of this investigation was to study the effects of continuous lighting exposure on the testes of the African giant rats (AGR). Samples of testes from twelve (12) healthy AGR were investigated under two groups. The rats were divided into two groups of 6 rats each as follows: Group I - Control rats (12 h light/12 h darkness); Group II - Rats exposed to continuous light (24 h). The indices of the testes were length, width, and weight of the organ, estimation of serum levels of testosterone, luteinizing hormones, follicle stimulating hormone (FSH) by radioimmunoassay (RIA) technique and histological studies of the testes. The mean body weight of the rats exposed to continuous light was 1.086 ± 0.034 kg which was reduced by 3.9 % from the control (1.131 ± 0.02 kg). The mean weight of the testes in rats, exposed to continuous light was 4.549 ± 0.30 g, which was significantly reduced by 17.8 %, when compared to the control (5.534 ± 0.16 g). The mean length and width of testes of rats exposed to continuous lighting was 0.294 ± 0.71 cm and 0.143 ± 0.48 cm, respectively. The mean serum level of testosterone in control rats was 1.225 ± 0.08 miu/ml and that in rats exposed to lighting, 0.275 ± 0.10 miu/ml. This result showed that the serum level of testosterone in male rats exposed to continuous lighting was reduced by 77.6 % from 1.225 ± 0.08 miu/ml in the control rats to 0.275 ± 0.10 miu/ml. Histological observations showed that the testes of rats exposed to light displayed elongated to round seminiferous tubules each with wide lumen lined by low germinal epithelium, and had wide interstitial spaces. Disruption of spermatogenesis and vacuolization of epithelial cells were evident. This study has shown that exposure of AGR for four (4) weeks of continuous lighting will result in disruption of spermatogenesis and decreased testosterone serum level.Keywords: Light; Testes; African giant ra

Biometric and morphologic studies of the female reproductive organs of the African giant rat (Cricetomys gambianus: Waterhouse)

Different segments of the reproductive tract of 100 adult, non-pregnant, female African giant rats (AGR) were carefully examined, weighed, and measured. The ovaries were observed to be small, pinkish, and kidney-shaped. The uterus of the AGR was found to be uterus duplex. The live weight of the AGR was 999.7 &#177; 16.86 g. The weight, length, and width of the ovary were 0.095 &#177; 0.003 g, 0.750 &#177; 0.01 cm, and 0.01&#177; 0.02 cm, respectively. The length of the oviduct, uterus, and vagina/vestibule were 4.44 &#177; 0.06 cm, 4.877 &#177; 0.11 cm, and 4.345 &#177; 0.07 cm, respectively. The weight and length of the entire tubular organs were 3.171 &#177; 0.01 g and 13.559 &#177; 0.18 cm with corresponding range values of 1.61&#8211;7.10 g and 7.80&#8211;17.40 cm, respectively. (Folia Morphol 2010; 69, 4: 213-215