PARENT SESSION
FERTILIZATION
Harborside C
7:30 AM-10:00 AM

(518) USE OF A PIEZO-ELECTRIC CERAMIC TACTILE SENSOR TO EVALUATE ZONA PELLUCIDA HARDNESS AT DIFFERENT STAGES OF PIG OOCYTE AND EMBRYO GENERATED IN VITRO.

Yoshida, Mitsutoshi¹, Imura, Hitomi¹, Murayama, Yoshinobu², Sakuma, Ichiro³, Tuji, Takayuki³, Omata, Sadao², ¹ Laboratory of Animal Reproduction, Kagoshima, Japan² College of Engineering, Koriyama, Japan³ Graduate School of Frontier Sciences, Tokyo, Japan

ABSTRACT- The hardness of zona pellucida (ZP) of mammalian egg has been mainly evaluated by biochemical method, such as a difference in egg dissolution speed with an enzyme or an acid reagent treatment. However, the physical hardness of ZP is largely unknown. The objective of this study is to determine the physical hardness changes of ZP in pig egg during maturation and after fertilization in vitro with a newly developed system using a piezo-electric ceramic tactile sensor. Measurement system: the thin glass needle was connected at the tip of a piezo-electric ceramic tactile sensor, and the sample was penetrated into a sensor at fixed speed under the computer controlled micromanipulation system. The amount of frequency change at the time of penetration was recorded using the computer program. Measurement of the gelatin sample of known concentration (2 - 6%) was used to determine the basic characteristic of a sensor and to make a standard curve. The methods for IVM and IVF of pig oocytes were largely based on those described previously. Immature oocytes (GV) immediately after collection, mature oocytes (MII) at 42 hrs of IVM, pronuclear (PN) stage of embryo at 12 hrs of postinsemination and blastocyst (BL) at 168 hrs of postinsemination were used for measurement of ZP hardness. When a sensor contacted with a harder gelatin sample, the amount of frequency change was large, and it turns out that the amount of change has the characteristic of being small for a softer gelatin sample. When a sensor contacted with ZP of pig egg, the amount of frequency change was decreased during maturation and after development. By comparison with a standard curve, ZP hardness converted into gelatin concentration in each stage of pig egg were 3.9% (GV), 3.6%(MII), 3.7% (PN), 2.6%(BL), respectively. The results indicate that this measurement system is very effective method to evaluate the physical ZP hardness of pig eggs and ZP hardness in pig eggs modulate during maturation and after fertilization in vitro.

KEY WORDS: zona pellucida, physical hardness, pig egg, tactile sensor