Starts 15 May 2026 14:00
Ends 15 May 2026 15:00
Central European Time
QLS Seminar - Model of Sperm–Oocyte Penetration Mechanisms
ICTP
Common Area Old SISSA building, Second floor
Via Beirut, 2
Existing theories of sperm–oocyte penetration can be classified into three main categories: biochemical receptor–mediated mechanisms, maximum normal stress–based penetration, and oscillatory relaxation mechanisms. Previous mechanical probing studies of zona pellucida (ZP) demonstrate increased structural resistance under higher perpendicular loading, implying that penetration is favored along directions of reduced mechanical resistance. Experimental observations indicate that sperm penetration of the ZP follows an oblique trajectory. Motivated by these findings, a modified mechanical model of ZP deformation is proposed to quantify normal and shear stresses generated during plastic sperm–oocyte collision. Numerical simulations were conducted for three distinct sperm distribution scenarios over the ZP surface. The results show time-dependent oscillations of both normal and shear stresses, with normal stress consistently exceeding shear stress across all scenarios. The observed stress fluctuations may contribute to oscillatory states of the ZP and could play a significant role in the mechanical mechanism of sperm penetration. The theory of phase transition of ZP as a potential mechanism of sperm penetration will be discussed.