Reproduction

Concannon, P.; Pilbeam, T.; Travis, H.

doi: 10.1530/jrf.0.0580001pmid: 7359464

Summary. Adult and pubertal female mink mated on 4 March were administered 2·5 mg medroxyprogesterone acetate (MPA) or control vehicle on 9–11 March. Pregnancies were shorter (P < 0·01) in adult (60 ± 2 days) than in pubertal (72 ± 0·7 days) control animals. Treatment with MPA reduced (P < 0·01) the length of pregnancy in both adult (51 ± 1 days) and pubertal (60 ± 2 days) mink but did not significantly affect serum progesterone levels on 3–4 April. Observations at laparotomy during April confirmed the effects of age and treatment on the time of implantation and suggested that implantation sites become grossly visible 28 days before parturition. It is concluded that administration of a progestagen during early embryonic diapause can advance the time of implantation in mink.

Hattersley, J. P.; Drane, Hilary M.; Matthews, J. G.; Wrathall, A. E.; Saba, N.

doi: 10.1530/jrf.0.0580007pmid: 7359492

Summary. Oestrone sulphate was extracted from pig serum with tetrahydrofuran and then hydrolysed with sulphatase. The radioimmunoassay of liberated oestrone was carried out directly on the reaction mixture. Oestrone sulphate concentrations were <60 pg/ml in non-pregnant sows. Detectable concentrations of oestrone sulphate were found in serum as early as the 18th day of gestation, and these rose to maximum levels of 2·1–3·5 ng/ml by Days 26–29 then fell to about 0·1 ng/ml by Day 37. Serum oestrone sulphate concentrations were not related to litter size, but were good indicators of early pregnancy.

Challis, J. R. G.; Greenblatt, Ellen

doi: 10.1530/jrf.0.0580013pmid: 7359468

Summary. The distribution of radioactivity within the fetal membranes and uterine tissues from pregnant rabbits after an intra-amniotic injection of [3H]oestrone sulphate was determined, and the conversion to oestrone and oestradiol-17β during in-vitro incubation of these tissues with [3H]oestrone sulphate was measured. After intra-amniotic injection, radioactive oestrone and oestradiol-17β were recovered from amniotic fluid, amnion, placenta, decidua and myometrium of the injected fetus, and, in some experiments, from tissues of an adjacent fetus. During incubation, extensive metabolism of oestrone sulphate occurred in placenta and chorion, and oestrone sulphatase and 17-oxidoreductase activities were found in these tissues as well as in amnion, decidua and myometrium. We suggest that oestrone sulphate, present in amniotic fluid, may be accessible for metabolism to unconjugated oestrogen by several intrauterine tissues of the pregnant rabbit.

Ratnasooriya, W. D.; Gilmore, D. P.; Wadsworth, R. M.

doi: 10.1530/jrf.0.0580019pmid: 7359477

Summary. Insertion of Silastic rods containing the directly acting sympathomimetic drug, methoxamine, adjacent to the epididymis of rats caused a temporary reduction in fertility with no loss of ability to mate. This effect lasted up to 3 weeks. At the time of the maximal antifertility action (3–7 days after insertion), the number of spermatozoa in the ejaculate fell to almost zero, and there was a reduction in the total number of spermatozoa in the epididymis resulting from a significant drop in the number present in the cauda. Methoxamine also caused immotility and decapitation of the remaining epididymal spermatozoa. The indirectly acting sympathomimetics, tyramine and norephedrine, did not affect fertility. It is postulated that methoxamine acts to induce infertility principally by bringing about a reduction of sperm numbers in the ejaculate. This could have been produced either by a failure of the vas and cauda to contract normally at copulation or because the sperm store in the cauda had fallen below a critical threshold level.

Scaramuzzi, R. J.; Baird, D. T.; Clarke, I. J.; Martensz, N. D.; Van Look, P. F. A.

doi: 10.1530/jrf.0.0580027pmid: 7188971

Summary. Ewes were immunized against androstenedione-11α-hemisuccinyl—bovine serum albumin (androstenedione-11–BSA) or BSA alone (controls). The ovaries were examined macroscopically and ovarian venous blood was collected at laparotomy by in-situ cannulation of the ovarian vein on Day 10 of the oestrous cycle, or by needle puncture of the ovarian vein 36 h after prostaglandin treatment. Follicular fluid was also collected from follicles >5 mm diameter in some ewes. Ovaries and adrenal glands were collected and examined histologically. Oestrone, oestradiol-17β, androstenedione, testosterone and progesterone were measured by radioimmunoassays. Immunization against androstenedione-11–BSA was followed by an increase in the number of surface follicles >3 mm in diameter and in ovulation rate. These changes were accompanied by an increased production of androgens (especially androstenedione) and of oestrogens during the preovulatory period. There were no observed changes in the adrenal cortex or pituitary glands, but the ovaries were heavier in immunized ewes and luteinized follicles were present in the ovaries of 1 of 4 immunized ewes.These results show that immunization against androstenedione-11–BSA leads to increased ovulation rate and suggest two possible mechanisms: (1) interference with the negative feedback effects of oestradiol-17β and/or (2) a reduction in the incidence of follicular atresia.

Farr, C. H.; Ellis, L. C.

doi: 10.1530/jrf.0.0580037pmid: 6244406

Summary. The effects of prostaglandin (PG) F-2α and E-2, cyclic GMP, testosterone and 2,4′-dibromoacetophenone (DBA) on rat seminiferous tubules in vitro were ascertained by measuring contractile frequency, size of contractions and tone (tubular diameter). PGF-2α (10−9–10−5 m) increased frequency and tone but not magnitude of contraction. Contraction frequency and tone were decreased by PGE-2 (10−9–10−5 m) but the size of contractions was again unaffected. Cyclic GMP (10−10–10−6 m) increased the frequency of contractions and tone and decreased size of contractions. Testosterone decreased the frequency and size of contractions and increased tone at concentrations of 10−9 to 10−7 but higher concentrations (10−6 m) reversed these changes. DBA (10−7–10−3 m) greatly decreased the frequency and size of contractions and tone and spontaneous contractions were abolished at 10−3 m. Our data strongly suggest that PGs, cyclic nucleotides and testosterone are all important in vivo in modulating contractility of seminiferous tubules and as such would participate in sperm transport from the testes.

McMurtry, J. P.; Floersheim, G. L.; Bryant-Greenwood, Gillian D.

doi: 10.1530/jrf.0.0580043pmid: 7359488

Summary. A biologically-active succinylated porcine relaxin was iodinated by a modification of the Bolton—Hunter method. Fibroblasts cultured from the mouse pubic symphysis and human skin were used to investigate relaxin binding sites. 125I-labelled relaxin binding to both cell types was time- and temperature-dependent. An accelerated rate of labelled hormone degradation (90%) was observed when both cell types were incubated at 37°C.Specific relaxin binding sites on the mouse and human cells were observed as other peptides, such as insulin, epidermal growth factor, glucagon, hFSH and human prolactin, failed to inhibit relaxin binding. Further results indicate that porcine relaxin is mitogenic to these specific fibroblasts because increasing concentrations (10−9 to 10−6 m) of this hormone stimulated cell growth in vitro. These data suggest that the effect of relaxin at the target tissue level is mitotic in nature.

Ohwada, S.; Tamate, H.

doi: 10.1530/jrf.0.0580051pmid: 7359489

Summary. In right and left testes of the same animals, the frequencies of degeneration of type A spermatogonia were almost equal. When one testis was removed, there was a negative correlation of the frequency of the degenerating spermatogonia in this testis and the other after 25 days.

Jakubowski, M.; Terkel, J.

doi: 10.1530/jrf.0.0580055pmid: 7359490

Summary. The present investigation examined, by study of daily vaginal smears, whether the interaction of virgin female rats with young affected the oestrous cycle. Virgins behaving non-maternally or maternally were continuously exposed to young for extended periods. (1) All non-maternal virgins continued to cycle while 87% of maternal virgins ceased to cycle when exposed to young, and entered a series of prolonged dioestrous phases, each lasting about 14 days. Likewise, all maternal parous non-lactating controls exposed to young entered prolonged dioestrus. (2) The dioestrous phase induced by young in virgins was characterized by the decidual response. (3) Young aged 4–9 days were as effective as 10–15-day-old young for inducing and maintaining the dioestrus. (4) Confinement of young in a wire-mesh basket showed that body contact with young was essential to establish dioestrus. (5) Body contact with young was sufficient to induce dioestrus in maternal virgins with excised nipples. (6) Once established, the dioestrus could be maintained for about 12 days after removal of young as early as Day 4 of dioestrus in virgin and parous non-lactating females, but removal of young on Day 6 from post-partum lactating females resulted in a rapid resumption of cyclicity. (7) Prolonged suckling during a series of dioestrous phases induced lactation in 61% of maternal virgins, as well as in all parous control females.

Yagil, R.; Etzion, Z.

doi: 10.1530/jrf.0.0580061pmid: 7359491

Summary. Androgen levels in blood and the behaviour of male camels were determined during 1 year. In the months January to April large amounts of androgens were found in blood serum (~30 ng/ml compared with ~2 ng/ml throughout the remaining months) as well as in a secretion from glands on the back of the neck (36 ng/ml). During this period when hormone levels were high the behaviour of the camels changed: they became unmanageable, blew-out a palatal flap from the mouth, vocalized, and spread urine over their backs with the aid of their tails. The changes in the sexual cycle of the male camels corresponded with the oestrous period in female camels.