The establishment of artificial indoor breeding systems for the Japanese monkey

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For the past two years we have investigated methods of artificial indoor breeding in the Japanese monkey. Our goal is to make the Japanese monkey, the seasonal breeder, as good experimental animal for biomedical researches which can breed throughout the year under laboratory conditions. Results obtained in the present investigation are as follows. 1) Results of whole year observations of serum hormone level, ovarian morphology, and testicular histology showed clear seasonal changes, and sexual function in both sexes declined distinctly in summer. 2) During fertile season in the winter, appropriate timing of ovulation was verified by laparascopy and sperm collected by electro-stimulation were introduced into the uterus through the vagina. The fertilization resulted in parturition was achieved in 3 out of 6 cases. 3) During infertile season in the summer, the ovulation was chemically induced and the artificial insemination attempted by the same methods as in the winter breeding period. H … More owever, pregnancy and partrurition were not achieved in all of 6 cases. 4) A sustained-release formation of a GnRH agonist was utilized maintain the sexual function during summer, but sufficient maintenance of activity was not achieved. 5) IVF (in vitro fertilization) was tested using sperms and mature ova acquired through electro-stimulation and chemically induced ovulation, respectively. Fertilization and two to six cleavages of the zygote were confirmed in 12 out of 16 cases. 6) Prosperous methods for preservative solution and freezing of sperms available to artificial insemination were established. 7) Fertilization and cleavage of the zygote during the summer sterile period were also achieved by ICSI (intra cytoplasmic sperm injection) using sperms and ova acquired through electro-stimulation and chemically induced ovulation, respectively. Fertilization and two to six cleavages of the zygote were confirmed in all of 4 cases. 8) On an attempt of embryo transfer (ET), embryos acquired by the above mentioned IVF and ICSI procedures were transferred to the oviduct of females under laparascopic observations but none of those became pregnant.As shown above, introduction of sperm into the vagina, being a convenient method of artificial insemination, is not an efficient method for breeding. Now, IVF,ICSI and ET investigated in the present study are expected to become good methods for the year round indoor breeding, through further studies for implantation and maintenence of pregnancies. Less