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Summary.Lymphatic vessels draining the uterus and ovaries were located within the mesometrium and along the utero-ovarian pedicle by injection of marker dyes into the uterine wall and/or ovary of sheep and goats. Afferent lymphatics drained from the uterus towards the utero-ovarian pedicle and alongside the uterine artery, while 4–12 ovarian lymphatics emerged from the sub-ovarian plexus. A complex lymphatic network was formed in the region of the utero-ovarian pedicle by anastomosis between uterine and ovarian lymphatics. Mixed lymph carried in ducts alongside the uterine artery and in the utero-ovarian pedicle drained into the medial iliac node(s) and lumbo-aortic nodes, respectively. There was no evidence for retrograde lymph flow between the uterus and ovaries, but the close proximity of utero-ovarian lymphatics and the ovarian artery may provide an additional pathway for countercurrent diffusion of prostaglandin F-2α.Afferent lymph collected after chronic cannulation of utero-ovarian ducts ipsilateral to an ovary bearing a corpus luteum contained a mean progesterone concentration which was 10- to 1000-fold higher than that in jugular vein plasma between 15 and 45 days of gestation. Uterine lymph collected after cannulation of utero-ovarian ducts followed by ipsilateral ovariectomy had a progesterone value equivalent to that in plasma. Protein concentration in utero-ovarian and uterine lymph was between 85 and 90% of that of plasma, while Na concentration was slightly higher, and Cl concentration slightly lower than that of plasma. The concentration of K was similar in both biological fluids, confirming that tissue damage of cannulated vessels was negligible. Cell numbers in utero-ovarian and ovarian lymph were low (200 leucocytes/mm3) and consisted mostly of lymphocytes (>94%). These studies show that leucocytes in lymph are exposed to a high concentration of progesterone, and possibly other related steroids, in the utero-ovarian network which is adjacent to an ovary containing a corpus luteum.

Summary.An in-vitro bioassay for inhibin based on FSH content or release by rat pituitary cells was validated for measuring inhibin activity in ovine plasma and lymph. Dose-dependent increases in inhibin activity were detected in peripheral plasma of 4 ovariectomized ewes 1 min after i.v. injections of ovine follicular fluid, and the half-life of inhibin in plasma for 2 ewes was 45 and 50 min, respectively.Inhibin was detected in ovarian lymph but not in ovarian or jugular venous plasma, even after treatment of ewes with PMSG to induce folliculogenesis. Destruction of visible follicles (> 0·5 mm diameter) on the ovaries of 4 PMSG-treated ewes by electrocautery was followed by a rapid and sustained decline in secretion of inhibin in ovarian lymph for up to 4 h. Ovarian lymph flow rates were either unchanged or slightly increased after cautery. Oestrogen concentrations in peripheral venous plasma declined within 15–30 min of cautery, but concentrations remained well above baseline. There was a significant decrease in peripheral progesterone concentrations in these same samples, but not until 2–3 h after cautery. FSH in peripheral plasma was depressed or non-detectable in PMSG-treated ewes and neither FSH nor LH concentrations in peripheral plasma were significantly altered up to 4 h after cautery of ovarian follicles.It is concluded that (a) antral follicles (>0·5 mm) are the source of inhibin present in ovarian lymph, and (b) the ovarian lymphatic system is a route by which inhibin could reach the peripheral circulation, particularly in the luteal phase when ovarian lymph flow rates are high.

Summary.A total of 18 fallow does, including pubertal, non-pregnant and pregnant adult does (6 per class), each received a single subcutaneous implant containing 18 mg melatonin on 4 occasions at 29–30-day intervals from 10 November 1986 (∼ 120-day treatment period). A further 18 contemporary does served as herd-mate controls. Two adult fallow bucks were treated the same and were run with the does until 16 March. Thereafter, 1 of 4 control bucks was run with the does until 1 June. Of the 6 pregnant does receiving implants within the last 40 days of their gestation, 4 failed to lactate after parturition in December 1986. The remaining 2 does successfully reared their fawns, as did the 6 contemporary controls. Mean (± s.e.m.) dates of first oestrus in 1987 were 27·6 February (±3·0 days) and 22·9 April (±0·8 days) for all treated and all control does respectively (P< 0·001). Pubertal does were generally later to exhibit first oestrus than were older does within their respective treatment groups. Return oestrus occurred only in 2 pubertal does (1 treated and 1 control) with remaining does conceiving to their first oestrus, as verified by plasma progesterone profiles. However, 5 (28%) of the treated does and 3 (17%) of the control does failed to maintain pregnancy and fawn in 1987. The mean (± s.e.m.) 1987 fawning date of the remaining does was 22·4 October (±2·7 days) for the treated group (N = 13) and 13·1 December (±0·8 days) for the control group (N = 15; P< 0·001). Mean (± s.e.m.) gestation length of treated does (238·9 ± 0·6 days) was significantly longer than that of control does (234·5 ± 0·4 days; P< 0·001). Of 13 fawns born to treated does, 4 (31%) died within 24 h of birth (mainly due to hypothermia) whereas all 15 fawns born to control does survived to weaning.Melatonin-treated bucks exhibited a marked advancement of neck muscle hypertrophy during the treatment period and displayed normal rutting activity (e.g. vocalization) in response to early oestrus in the treated does.Keywords:fallow deer; Dama dama; reproduction; melatonin; oestrus; progesterone