Recipient Organization
UNIV OF PENNSYLVANIA
(N/A)
PHILADELPHIA,PA 19104
Performing Department
SCHOOL OF VETERINARY MEDICINE
Non Technical Summary
Agricultural animal production relies on reproductive efficiency. Sperm production in the testis forms the basis of male fertility. Many aspects of testis function have remained elusive because spermatogenesis can not be recapitulated in vitro and is difficult to manipulate in intact large animals. To provide a accessible system for to study spermatogenesis in agricultural animals that maintains essential structural integrity of the tissue, we previously developed testis tissue transplantation to mouse hosts (xenografting). The goal of this project is to apply testis tissue xenografting to the study and manipulation of spermatogenesis in farm animals. The project will explore effects of hormonal alterations on bovine spermatogenesis and attempt to rescue fertility of equine testes retained in the abdomen that cannot produce sperm. We expect to improve sperm production in bovine testis tissue and to demonstrate that functional germ cells are maintained in retained equine
testes. The project will also further develop a system for de novo formation of functional testis tissue from isolated testis cells. This will elucidate the role of different testis cell types in male fertility. The approaches employed in this project allow for the first time to study and manipulate reproductive function in farm animals without having to perform experiments in the target species. Insights gained in this experimental system can then be applied to improve male fertility. In addition, the system enables systematic study of cellular function that control sperm production in the testis.
Animal Health Component
20%
Research Effort Categories
Basic
80%
Applied
20%
Developmental
(N/A)
Goals / Objectives
The objective of this project is to apply the technique of testis tissue xenografting to the study and manipulation of spermatogenesis in farm animals. Specifically, we aim to improve spermatogenic efficiency in bovine testis tissue xenografts, to apply testis tissue xenografting to the study of testicular pathophysiology, and to establish xenografting of isolated testis cells as a novel model system for the manipulation of spermatogenesis.
Project Methods
Small fragments of testis tissue obtained from castrations of cattle and horses of different ages will be grafted under the back skin of castrated male nude mice. Comparable tissue pieces will be fixed at the time of grafting to serve as reference for graft development. Eight grafts per mouse will be placed under the skin of each mouse through small incisions. Inclusion of excurrent tissue in grafted testis tissue pieces will be studied for its effect on fluid accumulation. The effects of transient suppression of thyroid function or partial suppression of androgen production on testis function will be studied by treatment of host mice with PTU or acyline, respectively. Developmental potential of germ cells in cryptorchid equine testes will be assessed by exposure to the permissive environment in the host mouse and supplementation of equine FSH. The novel approach of de novo morphogenesis of testis tissue reconstituted from isolated cells will be further developed by
aggregation of cell populations enriched in porcine germ cells with testicular somatic cells to enhance the degree of spermatogenic differentiation in newly formed testis tissue. Mice will be sacrificed at different time points post-implantation for analysis of graft development and blood will be collected for hormone measurements. Grafts from all experiments will be fixed and processed for histology. Status of testis development and germ cell differentiation will be assessed based on morphology and immunohistochemistry for germ cell specific markers.