Tetsuhiro Yokonishi

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With the increasing cure rate of paediatric cancers, infertility, as one of the adverse effects of treatments, has become an important concern for patients and their families. Since semen cryopreservation is applicable only for post-pubertal patients, alternative pre-pubertal measures are necessary. Here we demonstrate that testis tissue cryopreservation is(More)
Spermatogonial stem cells (SSCs) are the only stem cells in the body that transmit genetic information to the next generation. The long-term propagation of rodent SSCs is now possible in vitro, and their genetic modification is feasible. However, their differentiation into sperm is possible only under in vivo conditions. Here we show a new in vitro system(More)
It is known that cells of testis tissues in fetal or neonatal periods have the ability to reconstruct the testicular architecture even after dissociation into single cells. This ability, however, has not been demonstrated effectively in vitro. In our present study, we succeeded in reconstructing seminiferous tubules in vitro which supported spermatogenesis(More)
Research on in vitro spermatogenesis has a long history and remained to be an unaccomplished task until very recently. In 2010, we succeeded in producing murine sperm from primitive spermatogonia using an organ culture method. The fertility of the sperm or haploid spermatids was demonstrated by microinsemination. This organ culture technique uses the(More)
Mouse spermatogonial stem cells (SSCs) can be cultured for multiplication and maintained for long periods while preserving their spermatogenic ability. Although the cultured SSCs, named germline stem (GS) cells, are targets of genome modification, this process remains technically difficult. In the present study, we tested TALEN and double-nicking(More)
Male infertility is most commonly caused by spermatogenic defects or insufficiencies, the majority of which are as yet cureless. Recently, we succeeded in cultivating mouse testicular tissues for producing fertile sperm from spermatogonial stem cells. Here, we show that one of the most severe types of spermatogenic defect mutant can be treated by the(More)
In contrast to cell cultures, particularly to cell lines, tissues or organs removed from the body cannot be maintained for long in any culture conditions. Although it is apparent that in vivo regional homeostasis is facilitated by the microvascular system, mimicking such a system ex vivo is difficult and has not been proved effective. Using the culture(More)
We report a case of pancreatic metastasis from renal cell carcinoma detected 25 years after radical nephrectomy. A 74-year-old man, who had undergone radical nephrectomy for renal cell carcinoma at age 49, was found by computed tomography to have a strongly enhanced mass on the pancreatic head. The patient underwent pancreaticoduodenectomy and the(More)
We report a case of prolapse of a simple ureterocele presenting as perineural tumor. A 60-year-old woman presented with perineum pain and bleeding. A physical examination revealed a hard mass, 30 mm in diameter protruding from the external meatus. The computerized tomography, magnetic resonance imaging and cystography showed an uncharacterized tumor.(More)