The influence of sericin supplementation and chilling temperatures (4°C and 15°C) on the short-term storage quality and fertility of rabbit semen was assessed over 72 hours of storage. In experiment 1, pooled semen (from five ejaculates) was diluted to a concentration of 50M ml−1, and assigned to control, 0.1% and 0.5% sericin groups, stored at 4 or 15°C. Sperm motility, sperm kinematics, viability, membrane and acrosome integrity were assessed at 0, 24, 48, and 72 hours of storage. The experiment 2 and 3 were conducted to observe effect of sericin on bacterial growth and in vivo fertility. The results of experiment 1 showed that sericin treatment, storage temperature, and storage duration influenced progressive and total motility, as well as sperm kinematics. Similar effects were observed for acrosome integrity, membrane integrity, and sperm viability. The results of experiment 2 indicated the antimicrobial effects of sericin when sperm were stored at 15C for 72 hours. While promising pregnancy outcomes were observed with sericin treated sperm for 72 hours, these results not significantly different. The study conclusively demonstrates that sericin treatment enhances the quality of rabbit semen when stored at lower temperatures for longer durations. Antimicrobial effects of sericin could be a contributing factor to the improved in-vitro and in-vivo fertility of rabbit sperm.

This study investigated the relationship of acrosome reactions and fatty acid composition on fertility in boar sperm. The acrosome reaction of sperm was induced via methyl-beta-cyclodextrin (MBCD), and acrosome reaction, plasma membrane integrity, and fertility were analyzed. The fatty acid composition of the excess acrosome reacted sperm was determined via gas chromatography. The results showed that the acrosome reaction in sperm was induced over 85% of the time by 60 mM MBCD treatment, and the plasma membrane integrity was significantly decreased and was dependent on the MBCD level. The acrosome reacted sperm resulted in significantly higher saturated fatty acids (SFAs) and lower unsaturated fatty acids (PUFAs) than the non-acrosome reaction group. Moreover, the acrosome reacted sperm from 60 mM MBCD significantly decreased in vitro fertility and blastocyst formation relative to non-acrosome reacted sperm, and the acrosome reaction was positively correlated with SFAs and negatively correlated with PUFAs. Of these fatty acids, C22:5n-6 (docosapentaenoic acid [DPA]) and C22:6n-3 (docosahexaenoic acid [DHA]) were directly negatively correlated with the acrosome reaction (r = -0.982 and -0.947, respectively). In conclusion, the excessive acrosome reactions may occur by reducing the PUFAs, which may then dramatically decrease sperm fertility in pigs.

Sperm morphology can predict the reproductive male fertilizing potential. This study aimed to determine the morphological and morphometric spermatozoa characteristics from guinea pigs subjected to different photoperiodic stimulation. Thirty F1 guinea pigs were randomly assigned to three photoperiodic treatments: FT1 (photoperiod with 10L/14D LED light), FT2 (photoperiod with 10L/14D sunlight), and FT0 (room without direct light source). At 107 ± 9.8 days of age, sperm concentration and motility were higher in FT0 and FT1 (p<0.05); furthermore, there were no differences in nucleus length and ellipticity between FT0 and FT1, but FT1 was higher in perimeter and nuclear area, while FT0 was higher in roughness, regularity, midpiece length and tail (p<0.01). Expanding acrosome (Type 2) was more frequent in FT2, but there was variation in head measurements between all morphological categories. Pregnancy rate, calving age and mating age were higher in FT0, meanwhile FT1 initiated successful matings earlier (p<0.01). FT0 had a higher fertility rate, and FT1 age of mating and first calving were earlier than FT0 but no pregnancies were reported for FT2. The photoperiodic stimulation can increase the morphometric dimensions of guinea pig spermatozoa, favoring the reproductive characteristics, but sunlight could reduce their size due to heat stress.

Na⁺/H⁺ exchangers (NHEs) are known to be important regulators of pH in multiple intracellular compartments of eukaryotic cells. Sperm function is especially dependent on changes in pH and thus it has been postulated that NHEs play important roles in regulating the intracellular pH of these cells. For example, in order to achieve fertilization, mature sperm must maintain a basal pH in the male reproductive tract and then alkalize in response to specific signals in the female reproductive tract during the capacitation process. Eight NHE isoforms are expressed in mammalian testis/sperm: NHE1, NHE3, NHE5, NHE8, NHA1, NHA2, NHE10, and NHE11. These NHE isoforms are expressed at varying times during spermatogenesis and localize to different subcellular structures in developing and mature sperm where they contribute to multiple aspects of sperm physiology and male fertility including proper sperm development/morphogenesis, motility, capacitation, and the acrosome reaction. Previous work has provided evidence for NHE3, NHE8, NHA1, NHA2, and NHE10 being critical for male fertility in mice and NHE10 has recently been shown to be essential for male fertility in humans. In this article we review what is known about each NHE isoform expressed in mammalian sperm and discuss the physiological significance of each NHE isoform with respect to male fertility.