IVF Mail - Pronase

Pronase

By: Ricardo Bertolla,
30 September 2003


Question:
	Greetings, I am gathering information on the use of Pronase in assisted hatching for embryo transfer, and I would like to know general issues as to use it or not. Is anyone using it? Do you have results (good or bad)? Positive or negative aspects? Thank you in advance, Ricardo

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Dave Morroll, Guy's Hospital, London said on 11 October 2004

"Ricardo

I would question why you would wish to use pronase as a method of assisted hatching before human ET rather than the more established methods such as PZD and Acid Tyrodes. Bathing in pronase will cause global thinning but it is important to note that, whilst this has been reported to be effective in facilitating hatching in murine embryos, the structure of the human zona is somewhat different.

The human zona appears bi-layered when treated with AT (Gordon & Talansky, 1986) whilst the mouse zona is a single, easily dissolved layer. Because of this, cruciate thinning improves hatching in the mouse (Khalifa et al, 1992) but this method is not effective in the human (Tucker et al, 1993), perhaps due to the inner resilient layer being left intact. One might assume thinning with pronase would have the same effect, or lack thereof.

The myriad of methods (PZD, AT, laser) and variations in the application of these methods (global/cruciate thinning, breaching inner layer, hole size) make it virtually impossible to compare reports of the success, or otherwise, of assisted hatching. I see no reason why pronase should be more safe or more effective than the more routine methods."