Occurrence of placental scars in the uterus of the african elephant (loxodonta africana)
About: This article is published in Reproduction.The article was published on 1967-12-01 and is currently open access. It has received 20 citations till now. The article focuses on the topics: African elephant.
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34 citations
TL;DR: The elephant estrous cycle is the longest among all studied non-seasonal mammals to date as mentioned in this paper, and the predominant progestagen secreted by luteal tissues is not progesterone, but rather its 5-alpha-reduced metabolites.
32 citations
TL;DR: As has been demonstrated in other populations of free-ranging African elephants, most of the females in Kruger National Park were reproductively active; however, age and climate affected reproductive activity.
Abstract: To reduce elephant densities and preserve biological diversity, 14,629 elephants were culled from Kruger National Park, South Africa (1967–1999). Data were catalogued between 1975 and 1996 on 2737 male and female elephants, including pregnancy and lactational status for 1620 females (≥5 years of age) and, uterine and/or ovarian characteristics for 1279. This study used these data to investigate the effects of age and precipitation on reproduction. The youngest age of conception was 8 years (n = 6) and by 12 years of age all females were sexually mature. From the age of 14 years, the percentage of reproductively active females (pregnant and/or lactating) was >90%; however, this percentage declined when females reached 50 years of age. Overall, one-tenth of females were nonreproductive (not pregnant or lactating) at any given time, mostly in the youngest ( 50 years) age classes. Eighteen (3.3%) of the nonpregnant females had reproductive tract pathologies, including endometrial, uterine or ovarian cysts. There was a seasonal distribution of mating activity that correlated with the rainy season. As has been demonstrated in other populations of free-ranging African elephants, most of the females in Kruger National Park were reproductively active; however, age and climate affected reproductive activity.
Resume
Pour reduire la densite des elephants et preserver la diversite biologique, 14.629 elephants ont ete abattus dans le Parc National Kruger, en Afrique du Sud, entre 1967 et 1999. Des donnees ont ete recueillies entre 1975 et 1999, sur 2 737 elephants mâles et femelles, y compris le statut de gestation ou de lactation de 1 620 femelles (≥5 ans) et les caracteristiques uterines et/ou ovariennes de 1 279 d’entre elles. Cette etude a utilise ces donnees pour rechercher les effets de l’âge et des precipitations sur la reproduction. L’âge de conception le plus precoce etait de huit ans (n = 6), et a l’âge de 12 ans, toutes les femelles etaient sexuellement mâtures. A partir de l’âge de 14 ans, le pourcentage de femelles en reproduction active (pleines ou allaitantes) etait >90%; cependant, ce pourcentage diminuait lorsque les femelles atteignaient l’âge de 50 ans. Globalement, a tout moment, un dixieme des femelles n’avaient pas de reproduction active (ni pleines, ni allaitantes) surtout parmi les plus jeunes ( 50 ans). Dix-huit (3,3%) des femelles non pleines souffraient de pathologies du systeme reproducteur, y compris de kystes de l’endometre, de l’uterus ou des ovaires. Il y avait une distribution saisonniere des accouplements, en correlation avec la saison des pluies. Comme cela a dejaete montre dans d’autres populations d’elephants africains vivant en liberte, la plupart des femelles du Parc National Kruger avaient une reproduction active; cependant, l’âge et le climat affectent l’activite reproductrice.
31 citations
TL;DR: The present study describes the anatomy of the female reproductive tract in T. inunguis and suggests that the Amazonian manatee undergoes infertile estrus cycles before its first gestation.
Abstract: The Amazonian manatee (Trichechus inunguis) is uniparous and has a slow reproduction cycle due to a long gestation period and long interval between births. Even though protected by law, hunting remains one of the main causes hindering the natural population growth of this species in the wild. The histology and reproductive anatomy provide information on the history and reproductive status of the female and offer a tool for the conservation of the species. The present study describes the anatomy of the female reproductive tract in T. inunguis. It is based on materials from three reproductive tracts fixed in 10% buffered formalin. The ovaries, uterine tubes, uterus, vagina, and external genitalia are described. The hymen presents two tiny openings separated by a segment that, upon rupturing during the first copulation, should make up a single vaginal opening. A still intact hymen and the absence of placental scars in the uterus were found in one specimen. Additionally, the presence of a hemorrhagic body and Graafian follicles on the right ovary were observed, as well as whitish scars and among them, possible corpora albicantia. These findings suggest that T. inunguis undergoes infertile estrus cycles before its first gestation. Macroscopically, counting of the whitish scars is hindered by the small diameter of these structures. It is not possible to differentiate between the scars resulting from ruptured (corpora albicantia) and nonruptured follicles (regressed corpora atretica). The presence of whitish scars on both ovaries of the same specimen suggests their bilateral function in T. inunguis.
20 citations
TL;DR: Detailed gross examinations of the reproductive tracts of three mature female nulliparous Asian elephants were conducted to develop artificial insemination (AI) techniques, of primary concern was the determination of the length characteristics and the size and configuration of the foramina between segments of the tract.
Abstract: Detailed gross examinations of the reproductive tracts of three mature female nulliparous Asian elephants were conducted to develop artificial insemination (AI) techniques. Of primary concern was the determination of the length characteristics and the size and configuration of the foramina between segments of the tract. The elephants were 13, 28, and 40 years of age and had been maintained in captivity for most of their lives. One elephant died naturally and two were euthanized for health reasons. The reproductive tracts of two of the elephants were manually palpated in situ via the urogenital canal. A fibreoptoscope was used to visualize the internal structures of the terminal reproductive tract of one elephant and to deposit dye into the vagina. The reproductive organs were removed from the body cavity, dissected, measured, and photographed. The major anatomical obstacles to overcome for standard AI procedures (the passage of an AI pipette into the reproductive tract) were the length of the urogenital canal (85–97 cm), the constriction at the urogenital-vaginal junction, and the tight cervix. The reproductive anatomy was compared to that of previous dissections reported in the literature.
15 citations
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TL;DR: The findings are discussed with reference to the phylogenetic position of the genus, the probable role of the corpus luteum in pregnancy, and the significance of the results in relation to the conservation of existing wild elephant populations.
Abstract: Between December 1946 and December 1948, and January to March 1950, 150 elephants made available in the course of control work carried out by the Uganda Game Department were examined in greater or less detail according to circumstances. Eighty-one were females, of which sixty-seven were adult and thirty-one had an embryo in the uterus. All the dissections were carried out in the field, and the present account includes observations on the terrain, the food of the elephant, and other aspects of its ecology. Linear measurements of the carcasses and photographs of the molar teeth provide a guide to the age of specimens. Tusk growth is nearly similar in males and females until puberty, after which those of females generally cease to grow. The reproductive organs of the male are briefly described; those of the female are described in more detail, and discrepancies between existing accounts are considered in the light of this relatively extensive series of specimens. The mode of formation of the ovarial sac is unusual and is described from foetal, neonatal and adult specimens. There is marked hypertrophy of the interstitial tissue of the foetal gonads during the later stages of gestation. Breeding occurs at all times of year, but mating is possibly more frequent in the period December to March than at other times. Both sexes reach maturity at 8 to 12 years, and the female continues to breed until old age. Parturition is followed by a lactation anoestrus, after which the female undergoes a number of brief oestrous cycles until pregnancy ensues, lactation being continued throughout the subsequent gestation period. The interval between parturition and subsequent conception is normally of the same order of duration as the gestation period, and the normal calving interval appears to be rather less than four years. The ovarian cycle of the adult is characterized by the occurrence of multiple ovulation and the presence of many apparently active and histologically indistinguishable corpora lutea in both ovaries at all the stages of pregnancy which were encountered. It is probable that the corpus luteum of pregnancy develops from one of a number of follicles which ovulate under the same hormonal stimulus, and that it persists together with the accessory corpora lutea, some of which arise from follicles which ovulate and some from follicles which luteinize without ovulating. The corpora lutea are replaced about mid-pregnancy by a second set, which are formed by the luteinization of all the follicles with antra in both ovaries; some at least of the larger ones ovulate while many smaller ones do not. Follicular growth is suppressed in the later stages of pregnancy. The cycle of events bears some resemblance to that which occurs in the mare, and the comparison is discussed in detail. The ovarian periphery is characterized by numerous subsurface crypts and papillose projections which increase the area of the germinal epithelium. A description of the placenta and foetal membranes is in preparation, and preliminary study reveals a striking similarity to Hyrax , particularly in the quadri-lobulate allantois. The findings are discussed with reference to the phylogenetic position of the genus, the probable role of the corpus luteum in pregnancy, and the significance of the results in relation to the conservation of existing wild elephant populations.
123 citations
"Occurrence of placental scars in th..." refers background or methods in this paper
...INTRODUCTION The elephant placenta is vasochorial, rather than, in the strict sense, endotheliochorial (Amoroso & Perry, 1965) and as Perry (1953) remarks in an earlier paper: "It is clear . . . that a considerable amount of maternal tissue comes away with placental tissue of foetal origin when the…...
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...For Western Uganda the material collected by Perry (1953) indicated a Downloaded from Bioscientifica.com at 04/27/2019 02:50:21PM via free access Placental scars in the elephant 449 mean calving interval of 3-8 years in the years 1947 to 1950; current research on the same populations suggests that…...
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...The elephant placenta is vasochorial, rather than, in the strict sense, endotheliochorial (Amoroso & Perry, 1965) and as Perry (1953) remarks in an earlier paper: "It is clear ....
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...For Western Uganda the material collected by Perry (1953) indicated a...
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