STEROIDS IN THE OVARIAN LYMPH AND BLOOD OF CONSCIOUS EWES

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Abstract
SUMMARY: Ovarian lymph was collected from seven conscious ewes over periods of 3–8 days. Rates of lymph flow from ovaries containing an active corpus luteum were 1·5–8·6 ml./hr./ovary and were much higher, per unit weight of tissue, than from any other organ studied in the sheep. Progesterone was isolated in crystalline state from this lymph. The concentration of progesterone (μg./100 ml.) in lymph collected from one ewe during the mid-luteal phase of the oestrous cycle was 71–205; during the 3rd month of pregnancy the concentration was 55–163, and 3 weeks before lambing it was 25. Thus the corpus luteum was fully active even when no longer considered essential for the maintenance of pregnancy. No more than one-tenth of the progesterone output appears to be carried from the ovary by the lymphatic route: the output in the ovarian lymph (mg./24 hr.) was 0·1–0·3 in the dioestrous ewe and 0·02–0·5 in the pregnant ewes; that into the ovarian blood was 1·4–1·9 in two conscious ewes on the 3rd day after oestrus, and 3·2–8·1 in three anaesthetized ewes on day 10 of the cycle. Lumbar lymph collected during the 4th and 5th month of pregnancy contained low concentrations of progesterone, suggesting that the concentration of progesterone in the tissue fluid of the uterus was also low. 20α-Hydroxypregn-4-en-3-one was present in the ovarian lymph during the 3rd month of pregnancy, but its concentration (0·6–1·6 μg./100 ml.) barely exceeded that in peripheral plasma (0·3–0·7 μg./100 ml.). 17α-Hydroxyprogesterone, a putative precursor of oestrogens, was identified as a secretory product of sheep's ovaries which contain a corpus luteum. During the 3rd month of pregnancy its concentration in ovarian lymph (μg./100 ml.) was 1·1–6·3, whereas the concentration in peripheral plasma was less than 0·5. The concentration of oestrogens in ovarian lymph was low: mid-luteal samples contained 30 mμg. oestradiol-17β/100 ml. and 13 mμg. oestrone/100 ml.; samples of lymph from pregnant ewes contained 3–7 mμg. oestradiol-17β/100 ml. and < 3–5 mμg. oestrone/100 ml. Androst-4-ene-3:17-dione and testosterone were not detected (< 0·5 μg./100 ml.) in ovarian lymph or blood. In six oestrous ewes secretion rates into the ovarian blood were < 1·2–17·9 μg. oestradiol-17β/24 hr. and < 1·2–4·8 μg. oestrone/24 hr., the lower rates were observed after ovulation had taken place. The output of progesterone and 20α-hydroxypregn-4-en-3-one was < 0·08 mg./24 hr. during oestrus. The volume of lymph flowing from the ovary during oestrus was small (approx. 0·2 ml./hr.) and did not permit chemical determination of steroids.