Independent Regression of Normal and Induced Corpora Lutea in Hysterectomized Guinea-Pigs

PLASMA PROGESTERONE LEVELS IN GUINEA-PIGS ACTIVELY IMMUNIZED AGAINST PROSTAGLANDIN F2α, HYSTERECTOMIZED OR TREATED WITH INTRA-UTERINE INDOMETHACIN

“…Moreover, typical vaginal cornification did not always occur at the time of oestrus, as indicated by the subsequent rapid rise in progesterone levels, though the vagina usually opened during this period. Similar findings have been reported previously for hysterectomized guinea-pigs (Deanesly & Perry, 1969). This makes suspect, studies in which the timing of oestrus is based solely upon vaginal opening and cornification in experimental guineapigs.…”

“…Progesterone levels were higher than 0-5 ng/ml for over 100 days in each cycle. Deanesly & Perry (1969) observed that by day 80 corpora lutea of hysterectomized guinea-pigs had lost two-thirds or more of their volume. They therefore found it surprising that these corpora lutea should still produce enough progesterone to inhibit ovulation and to maintain a mucified vaginal epithelium.…”

Stimulation of the hypothalamus and ovulation in the guinea‐pig

“…Although the response of the ovary to gonadotrophin and steroid treatment, and the control of corpus luteum function, have been investigated extensively in the guinea-pig (Loeb, 1923; Dempsey, Hertz & Young, 1936; Dempsey, 1937; Rowlands, 1961;Perry & Rowlands, 1963; Heap, Perry & Rowlands, 1967; Deanesley & Perry, 1965& Perry, , 1969Bland & Donovan, 1968, 1970, relatively little is known about the neural control of ovulation in this species. The results of experiments involving the placement of lesions (Dey, 1943; Dey, Fisher, Berry & Ranson, 1940) or surgical cuts in or around the hypothalamus (Butler & Donovan, 1971) establish the importance of this part of the brain of the guinea-pig in the control 374~J.…”