Spermatozoa, fertility

Cesari, A., Falcinelli, A. L., Mendieta, J. R., Pagano, M. R., Mucci, N., Daleo, G. R., Guevara, M. G. (2007). Potato aspartic proteases ( fAPs) exert cytotoxic activity on bovine and human spermatozoa. Fertil. Steril, 88, 1248-1255. 

MaMer, A., Reichler, A., StoUer, J. and Feigin, P.D. (1992). A new model for investigating in real time the existence of chemotaxis in human spermatozoa. Fertil. 

Pandya, I.J. and Cohen, J. (1985). The leukocytic reaction of the human uterine cervix to spermatozoa. Fertil. Steril. 41, 417-421. 

Vfllanueva-Diaz, G., Vadillo-Ortega, F., Kably-Ambe, A., Diaz-Perez, M.A. and Krivitzky, S.K. (1990). Evidence that human follicular fluid contains a chemoattractant for spermatozoa. Fertil. Steril. 54,1180-1182. 

The first cell cycle of the mouse embryo differs in many respects from the second and the following cell cycles. It is characterized by a long Gl phase that starts after the penetration of the spermatozoon or artificial activation of the oocyte. During this period the chromatin of the oocyte completes the second meiotic division and forms the female pronucleus. At the same time, in the fertilized egg, the highly condensed chromatin of the sperm nucleus decondenses and sperm-specific proteins, protamines, are replaced by histones. After the initial sperm chromatin... 

Fertilization is the fusion of the sperm and ovum. The sperm head binds to the plasma membrane of the egg (oolemma), and the entire spermatozoon enters the cytoplasm of the ovum. Only capacitated spermatozoa with intact acrosomes can enter and pass through the cumulus oophorus. The acrosome is a membrane-bound, cap-like structure covering the anterior portion of the sperm nucleus. The acrosomal reaction is the release of materials that lyse the glycoprotein coat (zona pellucida) surrounding the ovum. This is necessary for fertilization to take place. Before undergoing the acrosomal reaction, sperm go through a type of hypermotility called hyperactivation. The... 

Figure 6.48 Gametogenesis in humans showing the number of nuclear divisions giving rise to the gametes. Each average fertilizing spermatozoon is the result of 900 divisions of the primary spermatogonium.

Mammalian oocytes are surrounded by several layers of cells embedded in an extracellular matrix. This matrix has been shown to contain protein and hyaluronan [40]. The fertilizing spermatozoon must pass through it to reach the egg. In 1942 McClean and Rowlands demonstrated the possible role of hyaluronidase in dispersing and digesting the layers surrounding the oocyte [41]. Subsequent studies have shown that hyaluronidase is not essential, but is a helpful tool in assisting the passage of the individual sperm toward the oocyte [40],... 

Endler JA (1982) Pleistocene forest refuges fact or fancy In Prance GT (ed) Biological diversification in the tropics. Columbia Univ Press, New York, p 641 Franz6n A (1956) On spermiogenesis, morphology of the spermatozoon, and biology of fertilization among invertebrates. Zool Bidr Upps 31 355-482... 

Perotti ME (1973) The mitochondrial derivative of the spermatozoon of Drosophila before and after fertilization. J Ultrastruct Res 44 181-198... 

Perotti ME (1974) Ultrastructural aspects of fertilization in Drosophila, In Afzelius BA (ed) The functional anatomy of the spermatozoon. Pergamon, Oxford, p 57... 

Hesperidin derivatives have been shown to act as inhibitors of hyaluronidase (Beiler and Martin 1947,1948) and, as a rather remarkable application of this property, hesperidin solubilized by phosphorylation has been shown to suppress fertility (Sieve, 1952). It is suggested that the phosphorylated hesperidin, which can be administered orally, produces its effect by inhibiting the liquefaction of a hyaluronic acid gel which is necessary before the spermatozoon can penetrate the ovum. Since the results vary with different preparations, Martin (1953) suggests that the effect is due to one particular component of a complex mixture of phosphorylated derivatives. Insofar as both the aglycone hesperetin and its 7-rhamnoglucoside hesperidin, unless phosphorylated, are extremely insoluble, it is unlikely that any such action can be expected of the flavanones themselves when present in foodstuffs. 

Colwin, L.H. and Colwin, A.L. (1961) Changes in the spermatozoon during fertilization in Hydroides hexagonus (Annelida). 1. Passage of the acrosomal region through the vitelline membrane./o r a/ of Biophysical and Biochemical Cytology, 10,231-254. 

---