Analysing mammalian fertilisation: reservations and potential pitfalls with an in vitro approach

Abstract

There can be little doubt that one of the major technical advances in the discipline of mammalian reproductive physiology in recent years has been the development and refinement of procedures of cell maintenance and culture outside the body. Such in vitro systems have been applied, for example, to questions of (1) ovarian follicular physiology, especially the respective hormonal contributions and interactions of granulosa and theca interna cells, (2) oviduct and uterine activity, especially the novel secretions of endosalpinx and endometrium at different stages of the reproductive cycle, and (3) maturation of gametes, especially endocrine support of the resumption of meiosis in artificially liberated oocytes and the requirements for final maturation (capacitation) of epididymal or ejaculated spermatozoa, either fresh or cryopreserved. Establishment of in vitro systems has been assisted and encouraged by the ready availability of chemically-defined culture media, disposable plastic dishes and tubes, and computer-controlled incubators set to predetermined gas phase, humidity and temperature. Laminair flowhoods for tissue preparation and culture laboratories with filtered air and ultraviolet irradiation have together reduced problems of contamination and infection. Overall, the technical standards are impressive and inspection of modern tissue culture facilities invariably generates confidence in the quality of studies being pursued. In a phrase, such aesthetically pleasing and excellent laboratory facilities must surely be producing excellent science.