Equipment. The best images of the cervix and caudal uterus in these species were obtained with hand-held 5.0 MHz linear array transducers for sagittal images, and 3.5 (90?) MHz convex transducers for cross-sectional images. For the African species, the 5.0 MHz linear-array transducer was attached to an extension to enable imaging of the ovaries or ovarian area; however, for the R.unicornis, the 5.0 (48?) MHz convex transducer, taped to an extension, imaged the left ovary that was cranial to the probe.
Gross anatomical examinations of the penis and testicles were performed in Ceratotherium simum, Diceros bicornis, Rhinoceros unicornis. The testicles are extra-abdominal and are located within the same skinfold as the penis. The testicles are oblate spheroids with a cranial-caudal longitudinal axis. The long axis becomes more vertical if the testicles are drawn up toward the inguinal canal.
Distances from the vulva to the ovary: bicornis 70 cm unicornis 85 cm simum 90 cm End
The male reproductive tract includes the bulbourethral, prostate and vesicular accessory sex glands, all within the pelvic canal. Ampullae were not evident in Ceratotherium simum, Diceros bicornis, Rhinoceros unicornis. The masculine uterus was evident in the African species.
The reproductive organs of male D. bicornis and C. simum are similar. The junction of the urethra with the urinary bladder is usually more cranial than the junction in R.unicornis. This results in a more developed pelvic urethra in the African rhinos. The prostate surrounds the neck of the bladder with two trapezoidal lobes joined by an isthmus. On vertical longitudinal cross-sectioning, the prostate appears as a hyperechogenic triangular structure with lines of hypoechogenic spaces that result from accumulated secretions in the parenchyma. The bilateral vesicular glands of all 3 species lie between the prostate and the neck of the bladder. They are cigar-shaped and extend cranially and slightly dorsally along either side of the bladder. These fluid-filled glands contain spherical anechoic alveolar pockets that are separated by echogenic septa.
Two male reproductive organs were examined. The junction of the bladder and urethra is located on the caudal pelvic brim. All of the accessory sex glands are in close proximity at the neck of the bladder and ventral to the rectum, approximately 5.0 cm cranial to the anal spincter. The paired dense hyperechogenic bulbourethral glands are dorsolateral to the urethra and just cranial to the anus. On vertical cross-sectioning ultrasound, they appeared round and were 1.8 cm and 2.5 cm in diameter. The irregular prostate surrounds the neck of the bladder and lies between and slightly cranial to the bulbourethral glands. The prostate is lobulated. The lobes stack together extending bilaterally from the urethra. The lobes may extend from the surface or may be cystic and filled with prostatic fluid. Its irregularity and uneven border makes it difficult to distinguish with ultrasound.
The reproductive organs of male D. bicornis and C. simum are similar. The junction of the urethra with the urinary bladder is usually more cranial than the junction in R.unicornis. This results in a more developed pelvic urethra in the African rhinos. The prostate surrounds the neck of the bladder with two trapezoidal lobes joined by an isthmus. On vertical longitudinal cross-sectioning, the prostate appears as a hyperechogenic triangular structure with lines of hypoechogenic spaces that result from accumulated secretions in the parenchyma. The bilateral vesicular glands of all 3 species lie between the prostate and the neck of the bladder. They are cigar-shaped and extend cranially and slightly dorsally along either side of the bladder. These fluid-filled glands contain spherical anechoic alveolar pockets that are separated by echogenic septa.
