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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01 Jan 2000
TL;DR: In the beginning, why don't you try to acquire something basic in the beginning? That's something that will guide you to comprehend even more re the globe, experience, some places, past history, amusement, and a lot more?
Abstract: Eventually, you will no question discover a new experience and finishing by spending more cash. still when? reach you take on that you require to get those every needs when having significantly cash? Why don't you try to acquire something basic in the beginning? That's something that will guide you to comprehend even more re the globe, experience, some places, past history, amusement, and a lot more?
66 citations
01 Jan 1978
TL;DR: This brief review will examine evidence of a consistent pattern of longevity and aging in the class Mammalia, although the paucity of data in some areas limits the discussion to a semiquantitative examination of the possibilities.
Abstract: The comparative analysis of aging patterns in mammals is at present in a highly fragmented state, because the data now available were gathered by investigators from various disciplines for various purposes, and are not all equally suitable for the purposes of this survey. Nevertheless, it is possible to discern evidence of a consistent pattern of longevity and aging in the class Mammalia. This brief review will examine this pattern, although the paucity of data in some areas limits the discussion to a semiquantitative examination of the possibilities.
56 citations
54 citations
TL;DR: Although the placenta itself is endocrinologically inert, the foetal gonads, which enlarge greatly during the second half of pregnancy can synthesize 5α-dihydryoprogesterone and other 5α pregnane derivatives from cholesterol and pregnenolone, which may synergize with progestagens secreted by the 2–8 large corpora lutea which are always present in the maternal ovaries throughout gestation to maintain the pregnancy state.
Abstract: The African elephant reproduces so efficiently in the wild that overpopulation is now a serious problem in some game parks in Zimbabwe, Botswana and South Africa. The female reaches puberty between 10 and 12 years of age in the wild and, when in captivity, shows oestrous cycles of 14–15 weeks duration. She readily conceives a singleton in the wild yet her uterus has the capacity for twins. She shows a gestation length of 22 months and, in the wild, shows a population density and feed dependent intercalving interval of 4–8 years. The trophoblast erodes the lumenal epithelium of the endometrium and stimulates upgrowths of blood vessel-containing stromal villi, which develop eventually into the broad, tightly folded lamellae of the zonary, endotheliochorial placenta. Significant quantities of leaked maternal erythrocytes and ferric iron are phagocytosed by specialized trophoblast cells in the haemophagous zones at the lateral edges of the placental band. Although the placenta itself is endocrinologically inert, the foetal gonads, which enlarge greatly during the second half of pregnancy can synthesize 5α-dihydryoprogesterone and other 5α pregnane derivatives from cholesterol and pregnenolone. These products may synergize with progestagens secreted by the 2–8 large corpora lutea which are always present in the maternal ovaries throughout gestation to maintain the pregnancy state.
48 citations
TL;DR: Milk collected from thirty wild African elephants immediately after they were shot contained an average of 5.1% protein, 9.3% fat and 3.6% lactose, and the contribution of capric acid to the total fatty acids increased with advancing lactation.
Abstract: 1. Analyses have been made of milk collected from thirty wild African elephants immediately after they were shot. 2. The milk contained an average of 5.1% protein, 9.3% fat and 3.6% lactose. The concentration of lactose decreased and the concentration of protein and fat increased with advancing lactation. Inorganic constituents were present in approximately the same proportions as in bovine milk. 3. The contribution of capric acid to the total fatty acids, previously shown to be extremely high, increased with advancing lactation. 4. The significance of these findings to the preparation of a milk for rearing young elephants by hand is discussed.
43 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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