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METHODS: Hemicastration was performed in C57BL/6 mice at a neonatal, prepubertal or postpubertal period between days of life (DOL) 2-4, 20-22 and 42-44, respectively. These mice and a control group whom did not undergo a procedure were sacrificed after physical maturity (DOL 80) and remaining testis was removed. We evaluated FSH levels, histology, body weight (BW), testis weight (TW) and testis long-axis (calipers). The larger testis was recorded for controls. ANOVA was used to determine statistical significance (p<0.05).RESULTS: Median neonatal and prepubertal TW were significantly greater than control; however, only the median TW/BW ratio in the neonatal group was significantly higher than control, implying the greatest degree of compensatory growth happened with earlier testis loss. Neonatal TW was also significantly greater than postpubertal TW. No difference in BW or testis long axis length in any group was detected (Figure 1). H&E evaluation showed similar degree of spermatogenesis and Leydig cell concentration among all mice. Mean FSH (ng/mL) was highest in postpubertal (105.9) followed by prepubertal (98.5), neonate (93.9) and control (61.2), suggesting lower global sperm production in mice with testis loss at a later age.CONCLUSIONS: Contralateral testicular hypertrophy occurred if testis loss was during the prepubertal period and our data implies that earlier testis loss may have a greater degree of compensation and maintained reproductive function. This challenges the notion that the testis remains quiescent during childhood as there must be a signaling cascade to promote testicular hypertrophy. To our knowledge, this is the first study to successfully perform hemicastration in neonatal mice. This model will be used to study molecular mechanisms that influence testicular growth after unilateral testis loss .

Proton therapy is increasing in utilization worldwide at a rapid rate. With process improvements in costs, footprints, and continued advances in the delivery of care, including intensity modulation and image guidance, proton therapy may evolve into standard treatment with photon radiation therapy. This chapter reviews process improvements in proton therapy and the application in modern care.