Fertilization sperm

Fig. 1. Dynamics of DNA methylation levels during mouse development. The methylation patterns of the oocyte and the rapidly demethylated after fertilization sperm create the combined methylation patterns in the early mouse zygote. During the first two to three cleavage divisions, the 5mC levels decrease further and stay low through the blastula stage. Post-implantation, the mouse embryo genome is methylated de novo the CpG islands remain mostly unmethylated. The primordial germ cells remain unmethylated. During gametogenesis specific parental (maternal or paternal) patterns of DNA methylation are established at imprinted loci (for further details see Refs. [13, 14]) (re-drawn from Ref [4]).

Testis histopathology Mating impairment of hormone production leading to lack of appropriate mating behavior Fertility sperm production/function affected... 

Epididymis histopathology Mating usually imaffected Fertility sperm maturation/function may be affected leading to a decrease in fertility/fecundity... 

Sod-Moriah, U.A., Shemi. D., Potashnik, G. Kaplanski, J. (1990) Age-dependent differences in the effects of l,2-dibromo-3-chloropropane (DBCP) on fertility, sperm count, testicular histology and hormonal profile in rats. Andrologia, 22, 455-462... 

In a cell manipulation experiment, a constriction together with two narrow channels ( 50 pm) at the corner of a large channel were fabricated on a PDMS chip (see Figure 8.12). This microfluidic method was devised to remove cumulus cells from individual bovine cumulus-oocyte complexes before in vitro fertilization. In natural fertilization, sperms release hyaluronidase that attack... 

All animal eggs are surrounded by egg envelopes which must be traversed by sperm on their journey to the egg surface. These egg envelopes are known by various terms in different organisms, being called the vitelline layer in sea urchins, the vitelline envelope in amphibians, and the zona pellucida in mammals. The fertilizing sperm must penetrate the egg envelope in order to fuse with the plasma membrane and transfer its haploid set of chromosomes into the cell cytoplasm. 

In vitro fertilization sperm toxicity test (protocol n°59)... 

Moricard, R. and Bossu, J. (1951). Arrival of fertilizing sperm at the follicular cell of the secondary oocyte. FertU. Steril. 2, 260-266. 

During fertilization, sperm acrosomal and plasma membranes are normally removed by the acrosome reaction and sperm-egg fusion, respectively. The sperm... 

During fertilization, sperm must first bind in a species-specific manner to the eggs thick extracellular coat, the zona peUucida or vitelline envelope and then undergo a form of... 

Another interesting system in which hyaluronan plays an important role is expansion of the cumulus oophorus during ovulation. In response to follicle stimulating hormone and a factor produced by the oocyte, hyaluronan synthesis by the cumulus cells surrounding the oocyte increases dramatically [32], A stable, gel-like matrix is formed between the cumulus cells due to crosslinking of hyaluronan by inter-a-trypsin inhibitor and TSG-6 [31, 32]. This matrix is responsible for the integrity of the cumulus cell-oocyte complex which is required for protection and transport of the oocyte during ovulation, entry into the oviduct and fertilization. Sperm-associated hyaluronidases allow penetration of this matrix at fertilization. 

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