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.     

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.     

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.     

Gonadotropin-dependent renin in the rat testes

Using specific anti-rat renal renin antibody, the presence of renin in the rat testis was demonstrated by biochemical determination of renin activity. There was no correlation between testicular and plasma renin activity, indicating independent control of testicular and plasma renin levels. Since specific immunohistochemical staining for renin had been observed exclusively in Leydig cells, the effects of hypophysectomy and gonadotropin treatment on the testicular renin were investigated. After hypophysectomy, renin level in the testis decreased significantly, whereas plasma renin was slightly increased. In contrast, testicular renin had remarkably increased through gonadotropin treatment. The results indicate the presence of gonadotropin-dependent renin in the Leydig cells, and suggest a role for it in regulating testicular functions.     

A beta-citryl-L-glutamate-hydrolysing enzyme in rat testes

An enzyme responsible for the deacylation of beta-citryl-L-glutamate to citrate and glutamate has been characterized in rat testis. The enzyme required manganese ion for full activity and was strongly inhibited by nucleotides such as ATP or GTP. The activity was localized in the particulate fractions. The enzyme favored N-formyl-L-glutamate greater than beta-citrly-L-glutamate greater than beta-citryl-L-glutamine in a decreasing order. The amidohydrolyase activity was highest in the testis and lung, a moderate activity was detected in heart, kidney and intestine, and low in brain, thymus, stomach, skeletal muscle, spleen and liver. These findings suggest that the amidohydrolase is different from any of amidohydrolases reported so far, amidohydrolase I (EC 3.5.1.14), II (EC 3.5.1.15), III, N-acetyl-lysine deacylase (EC 3.5.1.17) and N-acetyl-beta-alanine deacetylase (EC 3.5.1.21), and various peptidases.     

Ectopic testes in the Norway rat

Animals with ectopic testes, some unilateral (on either the right or left side) and some bilateral, have appeared in a colony of King-Holtzman rats. This heritable defect has been given the genetic symbol "ect." Females carrying the gene are unaffected by it. When such females are bred to apparently normal males, they produce no ect offspring. Since 25% of their F2 generation carry the gene, it is assumed it is autosomal recessive. Studies involving selective breeding for males with ectopic testes indicate that some males have genomes resistant to the expression of the ect gene and that the apparent thresholds essential to left side, right side, and bilateral expression appear to be a secondary control of the multifactorial type.     

Glycogen metabolism in human fetal testes

The ontogeny of glycogen synthetase, glycogen Phosphorylase and α-D-glucosidase, enzymes which are associated with glycogen metabolism and glycogen level has been studied in human fetal testes of gestational age ranging from 14–32 weeks. Glycogen synthetase activity reaches the peak value at 17–20 weeks of gestation, thereafter it decreases. α-D-Glucosidase activity increases with the advancement of pregnancy up to 28 weeks of gestation decreasing thereafter very rapidly. Phosphorylase activity remains more or less constant throughout gestation. The maximum increase in glycogen content at early stages of gestation (17–20 weeks) and gradual reduction with the advancement of pregnancy are correlated with histochemical observation by the periodic acid-Schiff technique.