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Summary. Captive females attained sexual maturity at an age of 9–16 months and conceived for the first time when 10–25 months old. Adult females were polyoestrous but did not cycle while lactating or when isolated from males. The length of the cycle varied from 17 to 42 days (mean ± s.d. 31·2 ± 6·5 days; n = 43) and females experienced 3–7 sterile cycles before conceiving. Pregnancy lasted for 93–94 days (93·5 ± 0·6 days; N = 4) and litter intervals varied from 296 to 500 days (385 ± 60·4; n = 10). Litter size varied from 1 to 3 (1·5 ± 0·66; n = 165) and the well-developed precocial young weighed 300–400 g (351 ± 47·4 g; n= 19) at birth. Captive females reproduced throughout the year with most litters (78·7%; n = 165) being produced between August and March.
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Summary. The general pattern of steroid secretion during the 30-day oestrous cycle of the Cape porcupine is that of a surge (25–176 pg/ml) in oestradiol-17β secretion at the time of perforation of the vaginal closure membrane, followed by an increase in progesterone concentrations, the latter attaining peak values (mean 5·9 ± 2·1 ng/ml) 8–19 days (13·8 ± 2·8 days) after vaginal opening. Copulation occurred after the oestradiol-17β surge and the length of the luteal phase of the cycle varied from 21 to 35 days (29·3 ± 4·7 days), this representing 93% of the length of the cycle. Perforation of the vaginal closure membrane was not always accompanied by an increase in oestradiol-17β levels and some instances (19%) of vaginal opening were not followed by an increase in progesterone secretion. The hormonal characteristics of the oestrous cycle of females housed with vasectomized males were similar to those of females housed with intact males.
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Summary. Plasma progesterone concentrations measured by radioimmunoassay in the Natal clinging bat remained below 2·01 ng/ml during lactational anoestrus but increased significantly during the period of delayed implantation. Values peaked at implantation but were followed by a significant decrease thereafter. Concentrations remained low (<6·0 ng/ml) during the initial period of fetal development (153–180 days post coitum) and attained peak values (85·6–181·3 ng/ml) 216–222 days after fertilization. The marked post-implantation increase in progesterone concentrations coincided with a significant increase in placental weight.
Keywords: bats; progesterone; implantation; pregnancy; seasonal
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Summary. Sexually mature female Cape porcupines kept under natural conditions of illumination and temperature did not conceive while housed within their natal groups. Before removal from their natal groups the sexually mature offspring copulated and experienced cyclic ovarian activity, but conception occurred only 70–120 days after dispersal. Mean oestrous cycle length of these females (36·9 ± 11·5 days; n = 34) was similar to that of breeding females (33·0 ± 11·64 days; n = 16), but mean peak plasma progesterone concentration (6·45 ± 6·03 ng/ml; n = 34) was significantly (P < 0·01) lower than that of cyclic breeding females (13·58 ± 6·98 ng/ml; n = 16). Mean progesterone concentration at oestrus in non-breeding females (0·72 ± 0·45 ng/ml; n = 34) was also significantly (P < 0·01) lower than that of non-pregnant breeding females (4·21 ± 2·44 ng/ml; n = 16). Reproductive inhibition within natal groups, in which only one female reproduces, therefore cannot be ascribed to a failure to copulate, but may be due to some factor inhibiting full expression of luteal activity or affecting ovulation.
Keywords: porcupines; reproductive inhibition; oestrus; progesterone
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Summary. The reproductive tract of the male Cape porcupine is morphologically and histologically similar to that of New World hystricomorph rodents. Males are reproductively active throughout the year and attained sexual maturity (complete spermatogenesis) at an age of 8–18 months. Testes weight, epididymides weight and seminiferous tubule diameter attained asymptotic values at the age of 23–30 months. A tendency towards seasonality in the activity of accessory glands, preceded and accompanied by an increase in circulating plasma testosterone values, may be considered as a factor enforcing seasonal breeding in females. Testosterone concentrations in pubertal males were significantly higher than those recorded in sexually mature males.
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Summary. The constituent cell types of the ovary of the porcupine were similar to those of New World hystricomorph rodents and accessory corpora lutea and luteal bodies were formed through the luteinization of the membrana granulosa or theca interna of antral follicles. All luteal bodies were histologically similar. The total volume of luteal tissue per female was not affected by fetal age and was unrelated to circulating concentrations of maternal plasma progesterone. Maternal plasma progesterone concentrations were correlated with fetal age. Follicular activity occurred throughout pregnancy but was not affected by fetal age or related to circulating values of oestradiol-17β. The formation of accessory corpora lutea during pregnancy is regarded as important in supplementing progesterone during pregnancy.
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Summary. Circulating concentrations of progesterone, progesterone-binding plasma proteins (PBPP) and oestradiol-17β in pregnant porcupines remained relatively low until Days 25–30 post coitum. Progesterone values peaked (102–180 ng/ml; N=3) 42–60 days post coitum and the rapid increase in oestradiol-17β concentrations approximated that of progesterone with peak values (170–210 pg/ml) being attained 60–85 days post coitum. The pattern of PBPP synthesis, as suggested by circulating concentrations, was closely related to that of plasma progesterone, with values remaining low (<20pmol/ml) until Day 31 post coitum, reaching peak levels at Days 50–56 and Days 73–77 post coitum. The production of PBPP during pregnancy is, as in related New World hystricomorph species, considered to be a mechanism which facilitates a reduction in the rate of progesterone metabolism during pregnancy.
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Summary. Ovaries, fetuses and plasma were collected from zebra mares shot in the Etosha National Park in Namibia between 15 and 25 August 1983. Ovarian weight was affected by reproductive status and most of the non-pregnant mares were anoestrous. The number of follicles varied between individuals and only pro-oestrous/oestrous mares had follicles larger than 20 mm in diameter. The largest follicle in pregnant mares was only 9 mm in diameter. Corpora lutea and corpora albicantia were found in non-pregnant as well as pregnant mares: 4 pregnant mares had only corpora albicantia. The presence of secondary corpora lutea could not be confirmed in any of the pregnant mares. Implantation was estimated to occur at around 73 days of gestation, and most mares (84%) had conceived between November and April. Peripheral concentrations of plasma progesterone during pregnancy varied from 0·5 to 2·4 ng/ml.
Keywords: zebra; reproduction; ovaries; seasonality; progesterone
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Summary. The properties of progesterone-binding proteins in plasma of pregnant Cape porcupines were investigated using radiolabelled progesterone and either progesterone or cortisol as competing ligands as well as native plasma and heated (60°C for 30 min) plasma.
The results demonstrated that plasma from pregnant porcupines contains corticosteroid-binding globulin, but that it constitutes a significant portion of plasma progesterone-binding proteins only during the early stages of pregnancy. Corticosteroid-binding globulin of porcupines appears to be as heat labile as that of guinea-pigs. Concentrations of progesterone-binding proteins in plasma increased during pregnancy to reach concentrations at the eleventh week that were 25 times higher than those of progesterone; concentrations increased significantly (r 2 = 0·88) with the increase in progesterone concentration.
The results indicate that plasma progesterone-binding proteins in Cape porcupines (Old World hystricomorph) are similar in composition to those in guinea-pigs (New World hystricomorph).
Keywords: Cape porcupine; plasma-progesterone-binding proteins
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The ligand specificity of progesterone and oestrogen receptors in the uteri of four nonpregnant, nonlactating African elephants, killed during routine culling in the Kruger National Park, were determined. The mean (± sem) K d values of the oestrogen (0.18 ± 0.019 × 10−9 mol l−1, n = 12) and progesterone (0.22 ± 0.025 × 10−9 mol l−1, n = 12) receptors were essentially similar when [3H]promegestone was used as radioligand in the progesterone receptor assays. However, when [3H]progesterone was used as radioligand, the progesterone receptor exhibited a significantly higher K d value (1.03 ± 0.132 × 10−9 mol l−1, n = 12) than that of the oestrogen receptor. The use of the different radioligands did not significantly affect the quantitative values obtained for the progesterone receptor. Both the oestrogen and the progesterone receptors displayed a high ligand specificity. The 5α-reduced metabolites of progesterone exhibited a high relative binding affinity for the progesterone receptor 5α-pregnane-3,20-dione: relative binding affinity = 43%; 5α-pregnane-3α-ol-20-one: relative binding affinity = 20%) but the synthetic antiprogestin RU 486 did not compete successfully with progesterone in competitive binding studies. However, norethindrone (relative binding affinity = 293%) competed successfully for binding to the progesterone receptor, and may have some potential in the future development of a technique to control reproductive output in the African elephant.
