Ultrasonic measurement of canine testes

The goals of the present study were to determine if ultrasonic measurement of testicular dimensions (length, width, and height) would provide an accurate assessment of canine testicular size (weight) and to determine the relationship of these measurements to animal body weight. The bodies of 30 intact male dogs of unknown health, breed or breeding history were obtained after the dogs were humanely killed at the local animal shelter. Total scrotal width (TSW) was measured by calipers and the length, width and height of each scrotal testis, excluding the epididymis, were measured by sonography. The testes were then excised and weighed, again excluding the epididymis. Multiple regression was used to predict total testicular weight from 1) only sonographic measurements (Model 1), 2) all testicular measurements (Model 2), 3) only total scrotal width (Model 3), and 4) only body weight (Model 4). In addition, stepwise multiple regression was used to identify models (Models 5 and 6) using external measurements of the testes which seemed most useful in predicting total testicular weight. Models 1, 2, 3, 4, and 6 yielded r(2) values 0.90, 0.94, 0.88, 0.48 and 0.95 respectively. Model 5 yielded an r(2) of 0.90, but the additional accuracy achieved by using the testicular height was minimal. Although sonographic testicular measurement accurately predicted testicular weight, the small degree of additional accuracy achieved over TSW measurement by calipers does not justify the use of sonography in each case. However, if a testicular ultrasound scan is being performed, the ultrasonic measurements could be used to predict testicular weight.     

Cryopreservation of adult cervid testes

Several species of cervids are currently classified as threatened or endangered due to a rapid decline in their populations. Sperm cryopreservation, in association with assisted reproductive technologies, can find application for the conservation of endangered cervids. In cases of unsuccessful sperm retrieval through other means prior to the death of the animal, adult testis is the only source of sperm. Recovery of viable sperm from adult testes depends on the effective preservation of testicular tissues through optimization of cryopreservation protocols. The present study evaluated combinations of 10% dimethyl sulfoxide (DMSO) with 0% or 80% fetal bovine serum (FBS) and 20% DMSO with 0 or 20% FBS for the cryopreservation of testicular tissues of three adult cervids using uncontrolled slow freezing protocol. The cryopreserved testis was compared to chilled tissue without cryoprotectants. Results revealed that testicular tissues of barking deer cryopreserved in 20% DMSO (D20) had all the analyzed 7 parameters (number of TNP1-, PRM2 and acrosin-expressing cells/tubule and, the number of viable, morphologically normal, acrosome intact, Annexin V-negative sperm) comparable to the chilled testis. However, testicular tissues of sambhar and hog deer cryopreserved only in D20S20 had 5 of 7 parameters comparable to the chilled testis. In conclusion, D20 is acceptable for cryopreservation of barking deer and D20S20 for sambar and hog deer testes.     

Understanding and evaluating bovine testes

The objective is to briefly review bovine testes and how they are assessed, with an emphasis on articles from Theriogenology. Scrotal circumference (SC) is the most common method to assess testicular size; it varies among individual bulls and breeds and is highly heritable. In general, a large SC is associated with early puberty, more sperm, a higher percentage of morphologically normal sperm, and better reproductive performance in closely related females. Consequently, there are minimum requirements for SC for breeding soundness. In prepubertal bull calves, there is an early rise (10–20 weeks of age) in LH, which is critically related to onset of puberty and testicular development. Feeding bulls approximately 130% of maintenance requirements of energy and protein from approximately 8 to 30 weeks of age increased LH release during the early rise, hastened puberty (approximately 1 month), and increased mature testis size and sperm production (approximately 20%–30%). However, high-energy diets after weaning (>200 days) often reduced sperm production and semen quality. A bull's testes and scrotum have opposing (complementary) temperature gradients, which keep the testicular temperature 2 °C to 6 °C cooler than core body temperature for production of fertile sperm (increased testicular temperature reduces semen quality). Infrared thermography, a quick and noninvasive method of assessing scrotal surface temperature, may be beneficial for evaluations of breeding soundness. The primary clinical use of ultrasonography in assessment of reproductive function in the bull is characterization of grossly detectable lesions in the testes and scrotum. In conclusion, testis size and function are critical for bull fertility, affected by nutrition, and readily assessed clinically.     

Histology of salmonid testes during maturation

The commonly applied classification systems of fish gonad maturity divide the maturation process into certain stages. However, the scales do not entirely reflect the continuity of the maturation process. Based on light microscope observations, the paper describes a comprehensive pattern of testicular transformations during maturation. The study was carried out on precocious underyearling and 1-year-old males of sea trout (Salmo trutta m. trutta L.), 1-year-old males of salmon (Salmo salar L.), and males of brown trout (Salmo trutta m. fario L.) aged from 7 months to 4 years. A total of 821 gonads collected during all seasons of the year were examined. The fish were fixed in Bouin's fluid. Histological slides of the mid-part of the gonad were made using the standard paraffin technique. The 3-6 microm sections were stained with Heidenhain haematoxylin. Histological changes of testes during maturation were similar in the three species studied. Immature and resting gonads contained type A spermatogonia in lobules only. The appearance of cystic structures containing type B spermatogonia in the lobules signalled the beginning of the sexual cycle in male gonads. Type B spermatogonia underwent synchronous mitotic divisions resulting in an increase in the total number of spermatogonia. As the spermatogenesis continued, the gonads showed a gradual increase in the number of cysts containing cells at all the spermatogenetic stages: type B spermatogonia, primary and secondary spermatocytes, spermatids, and spermatozoa. The well-formed spermatozoa were released to the lobule lumen once the Sertoli cells and spermatozoa connections broke up and the cyst disappeared. This was a continuous process observed throughout the spawning season. The spermatozoa were moved to the efferent duct. While some of the germ cells were completing spermatogenesis, the lobules contained less and less cysts with type B spermatogonia, primary and secondary spermatocytes, and spermatids; eventually all the cells completed spermatogenesis. At the end of maturation, vacuoles, up to 18.9 microm in final diameter (brown trout), appeared in the Sertoli cells. The vacuoles were visible in the lobule wall epithelium for a prolonged period of time. In most salmonid individuals examined, the reproductive cycles were observed to overlap. In some fish, the preparation for another cycle began very early, i.e., at the and of preceding spermatogenesis, which had not been observed before. Gonad maturation in some males was incomplete.     

Alternative splicing in the testes

Germ-cell differentiation is an ideal process for studying the effects of alternative splicing and there are examples of alternative splicing of genes involved in gene regulation and signal transduction at every stage of the spermatogenic pathway. A network of testes-specific splicing factor interactions has been uncovered and combining our knowledge of these RNAs and proteins should lead to an understanding of the regulation of alternative splicing and male fertility.