Homologous testis transplantation in dogs

Update on canine anorchia: A review

Abnormalities of the external genitals are an important issue in dog breeding because of the unfavourable qualities and characteristics of breeds, resulting in consistent economic losses. Despite their significance, little scientific attention has been given to these problems. Although there are several reviews on cryptorchidism in dogs, none have described anorchia. Testicular agenesis is a rare reproductive disorder with a congenital origin. Moreover, no author has described the diagnostic procedure for making a definitive diagnosis of anorchia in dogs. It is important to have a well-structured diagnostic scheme to help practical veterinarians make a confirmatory diagnosis. This review article aims to provide an update on canine anorchia diagnosis based on the poor research studies published in recent years. We have also contributed to the pathogenesis of this disorder using human medicine studies. Finally, the review includes therapeutic hypotheses that can be expanded in future studies.

Fertility after homologous prepubertal testis transplantation in the dog

Canine models of hereditary human diseases are widely used throughout the biomedical community, particularly when no suitable rodent model exists. In several models, the homozygote dogs die prior to puberty, or have substantially reduced fertility. Prepubertal transplantation of the testes was used to propagate the genotype of a mutant dog that would not otherwise have survived until puberty. The transplant recipient remained fertile 7 years postoperatively. To begin determining the factors necessary for successful function in testis transplants, prepubertal dogs that were dog leukocyte antigen (DLA) identical and disparate were examined for fertility and compared to the original transplant recipient as well as unoperated and sham-operated dogs. Immunosuppression was maintained with cyclosporine (CyA) and prednisone in the immediate postoperative period and CyA alone thereafter. The DLA-identical dogs demonstrated initial acceptance of the transplant, whereas one of two underwent chronic rejection. Both DLA-disparate dogs had subacute rejection prior to sexual maturity. These results demonstrate that homologous transplantation of prepubertal testes can be an effective method to preserve genotype in DLA-identical dogs. This model may also be useful for studying testis development and immunobiology.

Subcutaneous autologous testicle transplantation in Wistar rats

OBJECTIVE

To assess the hormone secretion and viability of subcutaneous autotransplanted testicles in Wistar rats.

STUDY DESIGN

Wistar rats were randomly divided into four groups: sham (group I, n = 4), bilateral orchiectomy (group II, n = 4), sliced autotransplantation group (group III, n = 4), and whole-testicle autotransplantation group (group IV, n = 4). Sexual behavior (genital sniffing, thrusting intromissions, mounts with pelvic thrusting frequency), serum testosterone levels, and body weight were measured eight weeks after the procedure.

RESULTS

Subcutaneous autotransplantation elicited an increased number of mounts (P < 0.007) and intromissions (P < 0.009) and a significant reduction in the latency of these two behaviors (P < 0.034) compared with castrated animals. The frequency of sniffing of the bodies of sexually receptive females was not affected by castration (P = 0.326). Serum testosterone in whole autotransplantation group (219.23; 184.02-229.23) was higher than for the sliced autotransplantation group (0.74; 0.54-0.91) and bilateral orchiectomy group (0.59; 0.4-0.82; P < 0.05). We demonstrated that testicles transplanted without vascular anastomosis maintain their hormone secretion and exert neuroendocrine function on sexual behavior in rats. Autotransplantation could be an important alternative means of gonadal preservation for oncological patients considered for oncological therapies.

Testis transplantation in male rainbow trout (Oncorhynchus mykiss)

The objective of the present study was to establish a procedure for the transplantation of an intact testis from one male rainbow trout (Oncorhynchus mykiss) to another individual and evaluate the reproductive function of the transplanted testis at sexual maturity. Isogenic (cloned) male rainbow trout were produced by crossing a completely homozygous male (YY) with a homozygous female (XX) to eliminate any problem of tissue rejection. Transplantation was performed on four pairs of sexually immature animals (n = 8); each served both as a donor and recipient. The left testis was removed by making a ventral midline incision to expose the body cavity and gonads. The left testis was disconnected at the anterior and posterior points of attachment and transferred to the recipient fish where it was placed in position adjacent to the pyloric cecae. The right testis was left intact. After 4 wk, the fish were injected (i.p.) twice weekly for 8 or 9 wk with salmon pituitary extract (1.5 mg/kg) to induce precocious sexual maturation. A similar number of untreated fish were maintained as controls. Following this treatment, all the fish were killed, and the right (intact) and left (transplanted) testes were removed, weighed, and sampled for sperm. Although the mean weights of the left, transplanted testes were significantly (P: < 0.05) smaller than the intact testes (transplants = 1.2 g; intact = 3.9 g), transplanted testes were present in all animals, had increased in mass, and were sexually mature containing sperm. The mean fertility, as measured by the proportion of eggs completing first cleavage, of sperm derived from transplanted testes (92%) was no different from the sperm obtained from intact testes (84%). Similarly, there was no difference in the number of embryos attaining the eyed stage of development, after 18 days of incubation, that were derived from transplanted (84%) or intact testes (85%).