Effect of climatic variables on seasonal morphological changes in the testis and epididymis in the wild rodent Microcavia australis from the andes mountains, Argentina

Abstract

It has been shown that seasonal changes, especially in arid areas have a large influence on gonadal changes of the species that inhabit these areas. We studied a wild hystricomorph Microcavia australis in its natural habitat in the arid Andes Mountains. Sampling of adult males was carried out every 2 months. After autopsy, testes and epididymides were weighed and processed to obtain histological samples. Testes were analyzed with a microscope to measure seminiferous tubule area and diameter for each sampled month. Epididymides were used to determine spermatozoon storage in the cauda region. Results illustrate morphological changes in the testis and epididymis along the year. A high output of sperm cells was detected from middle winter to middle summer and a complete shutdown of spermatogenesis at the end of summer. The initiation of testicular activity coincided with month with the shortest day length, in dry season and very low temperature. On the other hand, gonadal regression started in the middle of summer with long day length, in the wet season, and high temperatures. Rainfall, temperature, and day length seem to be important for the testis cycle. We suggest that photoperiod could be a good predictor for an oncoming period suitable for breeding, and males may probably use it as a signal to regulate gonadal activity.

Seasonal Changes in Morphology and Immunoreactivity of PDGF-A and its Receptor PDGFR-α in the Epididymis of Wild Ground Squirrels (<i>Citellus dauricus</i> Brandt)

“…This is an efficient strategy to ensure energy metabolism and successful breeding as an adaptation to the annually changing conditions in their habitat [27]. Meanwhile, these findings were also similar to the observations in roe deer [23], viscacha [25,28] and mountain cavy [24]. In roe deer, the epididymal duct with its surrounding tissue expanded as the breading season approached.…”

“…These findings suggested that seasonal changes in epididymal morphology and histology were closely associated with the immunoreactivity of the PDGF system in wild ground squirrels. In seasonal breeders, the morphology and function of the epididymis change is synchronized with testicular tissue and spermatogenesis [23][24][25][26]. The present study revealed that similar to the testis [21,22], epididymal morphology also showed a significant seasonal change throughout the year.…”

“…In viscacha, the corpus and cauda were the most sensitive segments to changes induced by the photoperiod, and spermatogenesis did not cease during the regression period [25,28]. In mountain cavy, a decrease in the weight of the testis and epididymis was found during the nonbreeding season, which was independent of the change in body weight [24]. Taken together, we suggested that a cyclical alteration in the growth and involution of the epididymis may be universal in seasonal breeding mammals.…”

Testicular histomorphometry and the proliferative and apoptotic activities of the seminiferous epithelium in Syrian hamster (Mesocricetus auratus) during regression owing to short photoperiod

“…In addition, the length of the seminiferous tubule decreased sharply only between MR and SR groups. In animals in which tubular sections have been observed in spermatocyte arrest, as in Syrian hamster, only parameters such as tubular thickness (Simeunovic et al, 2000) or variations in the epithelial, tubular, and interstitial areas (Velez et al, 2010) have been studied, although semiquantitatively. All this also applies to mammals and birds in which epithelial atrophy is stronger (Pelletier, 1986;Madekurozwa et al, 2002;Sch€ on et al, 2004;Blottner et al, 2006;Islam et al, 2010;Ara ujo et al, 2013;Luaces et al, 2013).…”

Lectin Histochemistry as a Tool to Identify Apoptotic Cells in the Seminiferous Epithelium of Syrian Hamster (Mesocricetus auratus) Subjected to Short Photoperiod

“…It is known that the testis is strongly affected by environmental changes (Auvigne et al 2010;Velez et al 2010;Wagener et al 2010;Aurich 2011;Fatet et al 2011). Thus, there are species whose non-breeding season is determined by a decrease in daylight hours, the so-called seasonal breeding animals of short photoperiod (Kr ol et al 2005;Sato et al 2005;Klonisch et al 2006;Islam et al 2009).…”