CHMs are purely androgenetic conceptions (only paternal genetic material is present) and usually diploid (2 paternal chromosome complements without a maternal chromosome complement) (16); most result from fertilization of an ovum devoid of maternal genetic material by a single sperm that duplicates (monospermy
; ~85%), (17-19) but a subset is due to fertilization by 2 sperm (dispermy).
In order to better understand the results obtained in the second experiment, the experiment 3 (n=619) aimed to assess fertilization and monospermy rates after IVF of low quality oocytes.
In the Experiment 3, although the fertilization rate was similar among all groups (P>0.05), the rate of monospermy in the group pre incubated for 1.5h was the highest (P<0.05) amongst all groups (Table 2).
In pigs, high sperm concentration and POEC increase oocyte penetrability and decrease monospermy rates when sperm pre-culture with POEC is limited to 2 hr; the presence of POEC during IVF increased the rate of monospermy.
In porcine, the oviduct-specific glycoprotein (OVGP1) increases the rate of monospermy in in vitro fertilized oocytes through induction of zona hardening and interaction with spermatozoa (42).
Effect of steroids and oviductal cells, from the different parts of the oviduct, on the incidence of monospermy in porcine in vitro fertilization.
Sperm penetration rate of oocytes matured with various concentrations of BHB Percentage of BHB concentration (mM) N oocytes penetrated 0 113 26.8 [+ or -] 1.84 (a) 0.1 140 36.4 [+ or -] 0.64 (b) 1 127 46.4 [+ or -] 1.27 (c) 10 136 16.6 [+ or -] 3.39 (d) Percentage of oocytes BHB concentration (mM) N * with monospermy
0 30 45.1 [+ or -] 7.44 (a) 0.1 51 46.9 [+ or -] 5.12 (a) 1 59 44.1 [+ or -] 6.58 (a) 10 23 48.2 [+ or -] 7.03 (a) (a,b,c,d) Values with different superscripts in a column are significantly different (p<0.05).
Monospermy is ensured after the fast polyspermy block by the collaboration of the two strategies--suppression of the acrosome reaction of the supernumerary sperm and blockage of sperm entry at the plasma membrane.
due to the egg membrane hyperpolarization at fertilization, ensures physiological monospermy in eggs of the crab Maia squinado.
Allele patterns for CHMs were consistent with monospermy in 25 cases (81%) and dispermy in 6 cases (19%) (Figure 1).
Monospermy was the most frequently observed mechanism for CHM (81%), whereas dispermy was always observed for PHM, consistent with previous studies.