Endocrinology, Vol 100, 745-750, Copyright © 1977 by Endocrine Society
Seasonal changes of plasma estradiol and progesterone in the Japanese monkey (Macaca fuscata fuscata)
T Aso, T Tominaga, K Oshima and K Matsubayashi
Department of Obstetrics and Gynecology, School of Medicine, Kyoto University, Japan.
The plasma levels of estradiol and progesterone in 5 mature female Japanese
monkeys (Macaca fuscata fuscata) throughout a breeding and nonbreeding
season were measured by radioimmunoassay. As the breeding season
approached, plasma estradiol levels started to increase and a few
elevations were detected. However, neither a plasma progesterone rise nor
menstrual bleeding was seen. Menstrual bleeding began in December and
recurred regularly 4 or 5 times at 4 week intervals until April. During
this period, cyclic estradiol elevations (150-250 pg/ml) and luteal
progesterone rises (2.0-5.3 ng/ml) were observed. After the last
menstruation in March or April, two animals showed an estradiol elevation,
but progesterone levels remained in the basal range and amenorrhea
persisted. These data indicated that female Japanese monkeys ovulate 4 or 5
times a year, i.e., their breeding season is definitely defined. The
changes of both steroids in transitional periods between nonbreeding and
breeding, and breeding and nonbreeding seasons, suggested that some
follicle development occurred in these periods. The elucidation of the
mechanisms involved in the seasonal variation of reproductive functions in
the Japanese monkey may provide useful information concerning some aspects
of amenorrhea in human females.
