Age-Related Changes in the Gross Morphology and Morphometry of the Testis and Epididymis of the African Greater Cane Rat (Thryonomys swinderianus)

This study evaluated age-related changes in the gross morphology and morphometry of the testis and epididymis of the African Greater Cane Rat (AGCR). Twenty pathogen-free cane rats used for this study were randomly divided into 4 groups; Group I - prepubertal (≤4 months), Group II - pubertal (>4≤12 months), Group III - adult (>12≤30 months), and Group IV - aged (>30 months) of 5 animals each. On day 8th of acclimatization, testis and epididymis were harvested from sedated cane rat, described grossly and standard morphometric parameters (length, width, circumference, weight, and relative weight) determined. Gross morphological observations in the testes of all the different age categories showed similar characteristically cream to milky-white coloration and ellipsoidal shape. The epididymis in the different AGCR group uniquely presents the same inverted S-shaped outline, loose attachment to the testis, and less distinct division into caput, corpus, and cauda segments. Testicular and epididymal morphometric parameters were significantly reduced in the prepubertal cane rat relative to other groups. The parameters consistently displayed an age-dependent increment with the advancing age of the animal. In conclusion, this study has shown that both testicular and epididymal gross morphometrics increase with age advancement and perhaps might be linked to the varying functional reproductive status of the different age groups of the African greater cane rat.

Morphological Characterization of the Developing Greater Cane Rat (Thryonomys swinderianus) Brain

Developmental mode along the altricial-precocial spectrum is well known to be influenced by brain development and maturation. The greater cane rat (GCR) is an indigenous precocial African rodent with uncommon phenotypes and life traits. This study was therefore designed to characterize and describe distinctive external developmental features in the prenatal GCR brain across the entire gestational length using the emergence and differentiation of external features of the brain vesicles. Four gross morphometric brain parameters (weight, length, width, and height) were evaluated and expressed as mean ± SEM. Relationship between all brain morphometrics and gestation length were analyzed using one-way ANOVA and linear regression. Developmental milestones in the prenatal GCR were then compared with closely related precocial mammals. The earliest time point with gross observable features in the prenatal GCR brain was at gestation day (GD) 60. The period with the most remarkable gross developmental features was noted between GD80 and GD100. Some of these gross features include differentiation of the cerebellar plate into vermis and lateral lobes, emergence of the piriform lobes, mammillary bodies, colliculi bodies, cerebral peduncles, and primordial pons. By GD130, most gross topographic neural features were already established. Cerebellar lobation and patterning at GD130 were the last recognizable gross developmental features noticed in the prenatal GCR brain. This coincided with the time of first eye opening in the GCR fetus. The developmental pattern observed in the prenatal GCR brain is similar to those noted in precocial rodent like the guinea pig. However, the onset of these milestones was delayed, and their duration was relatively shorter in the GCR. This study provides a frame of baseline reference of morphological brain features in the GCR embryos and fetuses that will be useful for fetal age estimation, for home grown neurodevelopmental and eco-toxicological studies, as this rodent is being proposed as a research model.

Uterine Leiomyosarcoma Associated with Cystic Endometrial Polyps, Chondriod Metaplasia and Uterine Horn Intussusception in a Greater Cane Rat (Thryonomys swinderianus)

A rare case of uterine leiomyosarcoma associated with chondriod metaplasia, cystic endometrial polyps and uterine horn intussusception in a greater cane rat was macroscopically, histopathologically, immuno-histochemically and ultrastructurally evaluated. The histopathological findings for this tumour were similar to those for leiomyosarcomas described in other species. Immunohistochemical examination demonstrated positive immunoreactivity of neoplastic cells with α-smooth muscle actin, desmin and vimentin. Ultrastructurally, nuclear and cytoplasmic features were consistent with leiomyosarcoma. These results revealed the tumour to be of smooth muscle origin. To our knowledge, this is the first reported case of uterine leiomyosarcoma associated with cystic endometrial polyps, chondriod metaplasia and uterine horn intussusception in a greater cane rat.

Peculiar epidermal peg pattern in cane rat skin

Skin is the largest organ in the body of man and animal where interdigitation of the dermal papillae with epidermal pegs enhances structural stability of the skin especially where frequent pressure is applied. Cane rats are robust rodents with stocky bodies. They are only found in Africa and only a single species known as Thryonomys has been found to exist. This work was designed to establish the nature of the interdigitating structural disposition of the epidermal-dermal interface in T. swinderianus (Greater cane rat) which may account for the fragility and easy tear of their skin. A total of twenty adult male greater cane rats were used. Three samples sized 1cm to 2cm were taken from each of 14 different body sites for histological evaluation for rete pegs. These pegs were generally few in six regions with the following average per light microscopic field: head (5.5±3.7), neck (1.0±1.7), forelimb (5.6±3.7), trunk (4.3±4.2), tail (1.0±1.7) and the hindlimb (6.3±5.3). The neck and the tail parts of the body have the least concentration of this structure compared to other regions evaluated. This few in number of rete pegs may account for the fragility of the skin which makes it difficult to restrain or handle without damage during research work procedures and management during domestication. Keywords: Epidermal pegs, Fragility, Histology, Peculiar, Thryonomys

Vimentin expression profiles in the testis and epididymis of prepubertal to aged African greater cane rat (Thryonomys swinderianus)

Introduction: Vimentin is a cytoskeletal protein that is expressed in different regions of the testicular and epididymal parenchyma with principal function of structural support. There is dearth of literature on testicular and epididymal vimentin expression in different ages of African greater cane rat (AGCR). Hence, this study investigated vimentin expression profiles in the testis and epididymis of prepubertal to aged AGCR. Methods: Twenty healthy AGCR procured from a commercial cane rat farm were used for this study. The rats were randomly divided into 4 groups (n=5) as follows; Group 1: prepubertal (1-4 months), Group 2: pubertal (5-11 months), Group 3: adult (12-30 months) and Group 4: aged (>30 months). Testicular and epididymal samples were harvested and processed for immunohistochemistry using anti-vimentin marker. Results: Testicular vimentin was expressed in the interstitium, perinuclear region and basal aspect of Sertoli cells and along the tip of elongated spermatids. In the various segments of the epididymis, vimentin expression was confined to the peritubular coat and interstitium (stroma and perivascular components). Vimentin staining intensity in the testis was significantly higher (p < 0.05) in the adult group relative to others and appeared to increase with age. For the epididymis, significantly higher (p < 0.05) vimentin intensity was observed prepubertally and decreased with age advancement. Significance: The result from this study has demonstrated that the testes of the adult AGCR as well as the epididymal segments of the prepubertal rat had increased vimentin intensities which are indicative of marked reproductive activity and robust content of undifferentiated cells respectively.