Progress in research on the reproductive function in the sand rat (Psammomys obesus): A review.

The Fat Sand Rat (Psammomys obesus, P. obesus) is a diurnal herbivore and phytophage, with seasonal reproductive behavior. The sexually active phase lasts from autumn to early spring and the sexually inactive phase from late spring to summer. In the past years, P. obesus has gained much attention as an animal model in biological and clinical research. It is a suitable model for diet-induced insulin resistance, non-insulin-dependent diabetes mellitus and obesity studies. In addition, the seasonal reproduction of P. obesus is gaining more and more attention. The current paper aims to review and sum up the progress in the understanding of the reproductive anatomo-histo-physiology of Psammomys obesus, in order to facilitate future research in this area and to expose further perspectives for researchers.

Advances in research on the biology of the desert rodent Gerbillus tarabuli: a review.

Selection of the appropriate species and strain of laboratory animals are among the scientist's major concerns. Tarabul's gerbil (Gerbillus tarabuli) is a small, seasonally breeding, desert rodent native to Africa. Despite its unique biological features, which make it an ideal model candidate for biomedical research, only a few reports have used it in research. Hence, the present review aims to provide more data about this species, covering all aspects of its biology, such as taxonomy, morphology, anatomy, ecology, wildlife biology, molecular biology, physiology, neurobiology, genetics, reproduction, development, evolutionary biology, and conservation biology, and covers current progress in exploration of G. tarabuli, discussing its valuable characteristics, which are widely useful for research in various fields. This review paper is destined for biologists, scientists, mammologists, zoologists, academics, and students.

Histomorphometrical study of the testis in the desert Rodent, Gerbillus tarabuli, sexually immature and adult during the annual reproductive cycle.

Our interest in the testicular study of the desert rodent, Gerbillus tarabuli, would provide a better comprehension of the seasonality of spermatogenesis in rodents. We thus performed a biometric, histomorphometric and statistical analyses in Gerbillus tarabuli sexually immature and adult during the annual reproductive cycle (active and regressed states of gonadal activity). For that, fixed testes were embedded in paraffin. Sections were stained using the modified Heidenhain Azan and then were subjected to morphometric measurements at the light microscopic level. The biometric study revealed a positive correlation between the body weight and the maturity state only, with an average of 20.8 ± 2.92 g in sexually immature Gerbils, 37.40 ± 1.86 g in the sexually quiescent adults (p < .01) and 40.40 ± 2.98 g in the sexually active adults (p > .05), while the testes weight (sexually immatures = 0.02 ± 0.003 g, sexually quiescent adults = 0.13 ± 0.01 g; p < .001 and sexually active adults = 0.27 ± 0.01 g; p < .001) and the gonadosomatic index (sexually immatures = 0.09 ± 0.02%, sexually quiescent adults = 0.36 ± 0.04%; p < .01 and sexually active adults = 0.68 ± 0.07%; p < .01) varied according to the maturity state and as well as to the season in the adults. Through the histomorphometric study, the tubular diameter showed a continuous increase from sexually immature Gerbils (72.83 ± 7.57 µm) to sexually quiescent adults (99.45 ± 4.34 µm) p < .05 then to sexually active adults (182.58 ± 5.22 µm); p < .001, this is explained by the appearance of a large lumen after puberty in the quiescent (26.32 ± 1.28 µm); p < .001 and the enlargement of the seminiferous epithelium in actives (75.11 ± 1.81 µm); p < .001. Besides, the nucleo-cytoplasmic ratio of Leydig cells (sexually immatures = 0.5 ± 0.02) diminishes significantly after puberty in the rest period (0.42 ± 0.03); p < .05 and then during the active period (0.24 ± 0.01); p < .001. These striking biometric and morphometric differences in Gerbillus tarabuli testis between sexually immature Gerbils, sexually quiescent and active adults, follow the photoperiod-induced changes in endocrine and exocrine functions and prove that Gerbillus tarabuli is a useful model to study histo-physiological relationships in the testis in order to develop a more complete understanding of spermatogenesis phenomenon.

Immunolocalization of RFamide-related peptide 3 in a desert rodent Gerbillus tarabuli during seminiferous epithelium cycle.

Gerbillus tarabuli is a nocturnal seasonal breeder desert rodent with a main breeding season in spring and summer, and sexual quiescence in winter. This species is an interesting model for studying testis function in rodents. Therefore, the present study was performed firstly to investigate the stages of seminiferous epithelium cycle of Gerbillus tarabuli with a histological, morphometric and statistical study. And secondly to investigate the expression and possible variations in cellular distribution of RFamide-related peptide-3 (RFRP-3) - the mammalian ortholog of avian gonadotropin-inhibitory hormone (GnIH) - during seminiferous epithelium cycle using immunohistochimestry. Our results showed for the first time that the seminiferous epithelium cycle in Gerbillus tarabuli comprises 14 well-defined stages according to the tubular morphology method. The seminiferous epithelium thickness showed a significant difference during the epithelium cycle, thus it was the only morphometric classification criterion of seminiferous epithelium cycle in Gerbillus tarabuli. The immunohistochemical study reveals, for the first time, the presence of RFRP-3 in Gerbillus tarabuli testes, in both testicular compartments: the tubular and the interstitial. RFRP-3 is expressed differently according to the seminiferous epithelium cycle, RFRP-3 seemed to be more expressed at the stages V-VII and XIII. RFRP-3 was detected in Sertoli cells (≈12%), spermatocytes I (≈19%), round and elongated spermatids (≈13%), and with a more important signal in Leydig cells (26.87%±0.07). These results indicated the importance of RFRP-3 in testicular function in Gerbillus tarabuli; its expression at the interstitial and germinal levels argues in favor of an involvement in androgens synthesis and in spermatogenesis specifically in meiosis and spermiogenesis. This action seems primordial from stages V-VII and XIII. Also, the study of the seminiferous epithelium cycle will enrich the histological identity of the species.