Chemotaxis to follicular fluid

Table 3. Mammalian sperm chemotaxis to follicular fluid.

Eabro, G., Eisenbach, M., Rovasio, R.A. and Giojalas, L.C. (2001). Capacitated rabbit spermatozoa respond by chemotaxis to follicular fluid. Submitted. 

ANP is a polypeptide hormone that is secreted in large quantities by the atrial portion of the heart and from a variety of other mammalian cell types. It exerts many of its actions via activation of particulate guanylate cyclase [16, 134]. ANP is present in human follicular fluids [163] and specific ANP receptors have been identified in human spermatozoa [144]. Sperm chemotaxis to ANP was demonstrated by sperm accumulation in capillaries with ascending [6] and descending [192] gradients and by choice assays [192] (Table 4). It is not yet known whether ANP is involved in sperm chemotaxis in vivo and whether the physiological chemoattractant for human spermatozoa is an ANP-like substance. Since chemotaxis to ANP at physiological concentrations can be observed only in the presence of a neutral endopeptidase inhibitor such... 

In conclusion, follicular fluid, bourgeonal, ANP, and RANTES are the only substances that have been demonstrated to act as chemoattractants for spermatozoa by assays that differentiate between chemotaxis and other processes causing accumulation (Table 1). ANP may not be a direct physiological chemoattractant but rather a guanylate cyclase activator. The significance of sperm chemotaxis to bourgeonal and RANTES is an open question. The identity of the chemoattractant(s) in follicular fluid has yet to be revealed. 

In view of the notion that chemotaxis is required for the selection of capacitated spermatozoa, faulty precontact sperm-egg communication may be one of the causes of male infertility, female infertility, or both. It is reasonable that, in the future, chemotaxis may be exploited as a diagnostic tool for sperm quality and male infertility and may be used as a biological sperm-selection procedure before in vitro fertilization, especially before intracytoplasmic single sperm insertion or for intrauterine insemination. Moreover, the chemotactic activity of a follicular fluid may be an effective way to monitor the possible effects of different ovulation induction protocols on the maturational status of oocytes aspirated for in vitro fertilization [2]. On the other hand, interference vwth sperm chemotaxis may represent an exciting new approach to contraception. 

Sun, F., Tur-Kaspa, 1. and Eisenbach, M. (2003). Chemotaxis of human spermatozoa to conditioned media of human cumulus-oocyte cells. In preparation. Sundfjord, J.A., Forsdahl, F. and Thibault, G. (1989). Physiological levels of immunoreactive ANH-hke peptides in human follicular fluid. Acta Endocrinol. 121, 578-580. 

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