Agnew, D.W., L. Munson, and E.C. Ramsay (2004). Cystic endometrial hyperplasia in elephants. Veterinary Pathology 41(2): 179-83.
NAL Call Number: 41.8 P27
Abstract: Most captive female elephants are nulliparous and aged and many have endometrial disease, factors that may hinder fertility. This study characterized the pathologic features and demographic distribution of endometrial lesions from 27 captive Asian (Elephas maximus) and 13 African elephants (Loxodonta africanus), 12- to 57-years of age. The principal lesion was marked cystic and polypoid endometrial hyperplasia (CEH), present in 67% of Asian and 15% of African elephants ranging from 26 to 57 years. The lower prevalence in African elephants likely reflects their younger age range in this study. Fourteen of 15 affected elephants with breeding information were nulliparous. These results suggest that CEH and polyps are common in aged nulliparous elephants, and the severity of these lesions may impair fertility. These findings will be useful in the interpretation of ultrasonographic findings during reproductive examinations of potential breeding cows. Also, breeding programs should focus on younger animals.
Descriptors: zoo animals, endometrial hyperplasia, endometrium pathology, fertility physiology, polyps, endometrial hyperplasia pathology, histological techniques, polyps pathology, species specificity.
Allen, W. R (2006). Review. Ovulation, pregnancy, placentation and husbandry in the African elephant (Loxodonta africana). Philosophical Transactions of the Royal Society of London. Series B Biological Sciences 361(1469): 821-34.
NAL Call Number: 501 L84Pb
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 5alpha-dihydryoprogesterone and other 5alpha 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.
Descriptors: African elephant, ovulation, placentation, husbandry, puberty, estrus cycles, pregnancy, endometrium, gestation, corpora lutea.
Allen, W.R., S. Mathias, and M. Ford (2005). Placentation in the African elephant, Loxodonta africana. IV. Growth and function of the fetal gonads. Reproduction 130(5): 713-720. ISSN: 1470-1626.
NAL Call Number: QP251.J75
Abstract: The gonads, both ovaries and testes, of 44 elephant fetuses weighing 0.09-112 kg (6.1-21.3 months gestation) were examined grossly and histologically. As in equids, elephant fetal gonads undergo a phase of marked growth and enlargement during the second half of gestation, which is more pronounced in ovaries than testes due to growth and antrum formation of numerous follicles in the former. Stromal cells undergo hypertrophy and transformation to form zones of interstitial cells that are associated with the enlarged follicles in the ovaries and in which the primitive seminiferous tubules are embedded in the testes. The interstitial cells have the capacity to synthesize 5[alpha]-dihydroprogesterone and other 5[alpha]-reduced progestagens from cholesterol and pregnenelone and the hypothesis is raised that these fetal gonadal progestagens may supplement significantly the progestagens secreted by the multiple large corpora lutea of pregnancy in the elephant.
Descriptors: African elephant, placentation, fetal gonads, ovaries, testes, gestation, growth, function, corpora lutea, follicles, seminiferous tubules.
Allen, W.R., S. Mathias, F.B. Wooding, and R.J. van Aarde (2003). Placentation in the African elephant (Loxodonta africana). II. Morphological changes in the uterus and placenta throughout gestation. Placenta 24(6): 598-617.
NAL Call Number: QP281.P53
Abstract: The gross and microscopic development of the zonary endotheliochorial placenta in the African elephant was studied in 22 gravid uteri that ranged in gestational stage from 0.5 to 20.6 months. The conceptus only ever occupies one horn of the uterus and is associated with 2-5 large corpora lutea that persist in the ipsilateral ovary throughout gestation. Initially, the trophoblast in the equatorial region of the conceptus completely replaces the lumenal epithelium of the endometrium to which it is apposed. Blunt upgrowths of endometrial stroma then develop, each closely invested by trophoblast, and containing the capillaries that will vascularize this maternal component of the resulting placental band. With advancing gestation the lamellate stromal upgrowths increase markedly in length and become much thinner, thereby bringing the trophoblast into intimate contact with the endothelium of the maternal capillaries. They also become folded or pleated to increase the total area of intimate feto-maternal contact. At the lateral edges of the placental band the lamellae bend over towards the endometrium to form a blind cleft. Leakage of blood into this area creates haemophagous zones in which phenotypically specialized trophoblast cells phagocytose the blood components. The presence of large resorbing blood clots and circumferential scars in the uteri of three post parturient animals initiated the hypothesis that, when the standing elephant gives birth at term, the passage of the 120 kg fetus through the vagina may wrench the placenta off the endometrium by severing its very narrow maternal placental hilus. The resulting intrauterine haemorrhage may then play a role in preventing further conception for around 2 years.
Descriptors: physiology, placenta embryology, placentation physiology, uterus anatomy and histology, gestational age, placenta physiology, trophoblasts physiology, trophoblasts ultrastructure, uterus physiology.
Brown, J.L., D. Olson, M. Keele, and E.W. Freeman (2004). Survey of the reproductive cyclicity status of Asian and African elephants in North America. Zoo Biology 23(4): 309-321. ISSN: 0733-3188.
NAL Call Number: QL77.5.Z6
Descriptors: reproductive cyclicity, status, survey, African elephant, Asian elephant, North America.
Brown, J.L., M. Somerville, H.S. Riddle, M. Keele, C.K. Duer, and E.W. Freeman (2007). Comparative endocrinology of testicular, adrenal and thyroid function in captive Asian and African elephant bulls. General and Comparative Endocrinology 151(2): 153-162. ISSN: (p) 0016-6480; (E) 1095-6840.
Descriptors: African elephant, Loxodonta africana, Asian elephant, Elephas maximus, comparative study, adrenal glands, hormone secretion, hydrocortisone, reproduction, sexual maturity, testes, testosterone, thyroid function, thyrotropin, thyroxine, triiodothyronine, cortisol, thyroid stimulating hormone, musth.
Brown, J.L., S.L. Walker, and T. Moeller (2004). Comparative endocrinology of cycling and non-cycling Asian (Elephas maximus) and African (Loxodonta africana) elephants. General and Comparative Endocrinology 136(3): 360-70.
NAL Call Number: 444.8 G28
Abstract: Up to 14% of Asian and 29% of African elephants in captivity are not cycling normally or exhibit irregular cycles based on progestin profiles. To determine if ovarian acyclicity is related to other disruptions in endocrine activity, serum pituitary, thyroid, adrenal, and ovarian hormones in weekly samples collected for 6-25 months were compared between normal cycling (n=22 each species) and non-cycling (n=6 Asian; n=30 African) elephants. A subset of cycling females (n=4 Asian, 7 African) also were blood sampled daily during the follicular phase to characterize the peri-ovulatory period. In normal cycling females, two leutinizing hormone (LH) surges were observed 3 weeks apart during a normal follicular phase, with the second inducing ovulation (ovLH). Serum FSH concentrations were highest at the beginning of the non-luteal phase, declining to nadir concentrations within 4 days of the ovLH surge. FSH remained low until after the ovLH surge and then increased during the luteal phase. A species difference was noted in prolactin secretion. In the African elephant, prolactin was increased during the follicular phase, but in Asian elephants concentrations remained stable throughout the cycle. Patterns of thyroid hormones (thyroid-stimulating hormone, TSH; free and total thyroxine, T4; free and total triiodothyronine, T3) and cortisol secretion were not affected by estrous cycle stage or season in cycling elephants. In non-cycling elephants, there were no fluctuating patterns of LH, FSH, or prolactin secretion. Overall mean concentrations of all hormones were similar to those in cycling animals, with the exception of FSH, prolactin, and estradiol. Mean serum FSH concentrations were lower due to females not exhibiting normal cyclic increases, whereas serum estradiol was higher overall in most acyclic females. Prolactin concentrations were significantly increased in 11 of 30 non-cycling females, all of which were African elephants. In sum, while there were no consistent endocrine anomalies associated with ovarian acyclicity, hyperprolactinemia may be one cause of ovarian dysfunction. The finding of elevated estrogens in some acyclic females also deserves further investigation, especially determining how it relates to reproductive tract pathologies.
Descriptors: physiology, estrous cycle physiology, ovary physiology, blood, estradiol blood, estrous cycle blood, follicle stimulating hormone blood, hydrocortisone blood, luteinizing hormone blood, prolactin blood, seasons, species specificity, thyrotropin blood, thyroxine blood, triiodothyronine blood.
Brown, J.L. and T.B. Hildebrandt (2003). The science behind elephant artificial insemination. Biology of Reproduction 68(Supplement 1): 95-96. ISSN: 0006-3363.
NAL Call Number: QL876.B5
Descriptors: reproduction, artificial insemination, clinical techniques, captive breeding, sperm cryopreservation, transrectal ultrasound, diagnostic techniques, imaging, estrous cycle, ovulation, parturition, pregnancy.
Dahl, N.J., D. Olson, D.L. Schmitt, D.R. Blasko, R.S. Kristipati, and J.F. Roser (2004). Development of an enzyme-linked immunosorbent assay (ELISA) for luteinizing hormone (LH) in the elephant (Loxodonta africana and Elephas maximus). Zoo Biology 23(1): 65-78. ISSN: 0733-3188.
NAL Call Number: QL77.5.Z6
Descriptors: African elephant, Asian elephant, ELISA, luteinizing hormone, enzyme-linked immunosorobent assay, LH, development.
Dahl, N.J., D.L. Schmitt, D.R. Blasko, and J.F. Roser (2004). A progesterone (p4) rise prior to and during the ovulatory luteinizing hormone (ovlh) peak may facilitate fertile ovulations in the African and Asian elephant (Loxodonta africana and Elephas maximus). Biology of Reproduction(Special Issue): 102-103. ISSN: 0006-3363.
NAL Call Number: QL876.B5
Descriptors: reproduction, infertility, disease, reproductive system disease, fertile, ovulation, progesterone rise, ovulatory luteinizing hormone, peak.
Dill, W.M., B.L. Davis, A.R. Hicks, T.E. Goodwin, L.E.L. Rasmussen, H. Loizi, and B. Schulte (2003). Chemical analysis of preovulatory female African elephant urine: a search for putative pheromones. Abstracts of Papers American Chemical Society 225(1-2): CHED 409. ISSN: 0065-7727.
NAL Call Number: 381 Am33PA
Descriptors: African elephant, urinary system, chemical analysis, urine, putative pheromones, preovulatory, female.
Freeman, E.W., E. Weiss, and J.L. Brown (2004). Examination of the interrelationships of behavior, dominance status, and ovarian activity in captive Asian and African elephants. Zoo Biology 23(5): 431-448. ISSN: 0733-3188.
NAL Call Number: QL77.5.Z6
Descriptors: ovarian activity, Asian elephants, African elephants, dominance status, behavior, interrelationships.
Freeman, E.W., G. Guagnano, D. Olson, M. Keele, and J.L. Brown (2009). Social factors influence ovarian acyclicity in captive African elephants (Loxodonta africana). Zoo Biology 28(1): 1-15. ISSN: 0733-3188.
NAL Call Number: QL77.5.Z6
Abstract: Nearly one-third of reproductive age African elephants in North America that are hormonally monitored fail to exhibit estrous cycle activity, which exacerbates the nonsustainability of the captive population. Three surveys were distributed to facilities housing female African elephants to determine how social and environmental variables contribute to cyclicity problems. Forty-six facilities returned all three surveys providing information on 90% of the SSP population and 106 elephants (64 cycling, 27 noncycling and 15 undetermined). Logistic analyses found that some physiological and social history variables were related to ovarian acyclicity. Females more likely to be acyclic had a larger body mass index and had resided longer at a facility with the same herdmates. Results suggest that controlling the weight of an elephant might be a first step to helping mitigate estrous cycle problems. Data further show that transferring females among facilities has no major impact on ovarian activity. Last, social status appears to impact cyclicity status; at 19 of 21 facilities that housed both cycling and noncycling elephants, the dominant female was acyclic. Further studies on how social and environmental dynamics affect hormone levels in free-living, cycling elephants are needed to determine whether acyclicity is strictly a captivity-related phenomenon.
Descriptors: African elephants, Loxodonta africana, captive animals, zoo animals, estrous cycle, body weight, social dominance, environmental factors, surveys, captive-elephants, ovarian acyclicity, acyclic females, noncycling females.
Ganswindt, A., H.B. Rasmussen, M. Heistermann, and J.K. Hodges (2005). The sexually active states of free-ranging male African elephants (Loxodonta africana): defining musth and non-musth endocrinology, physical signals, and behavior. Hormones and Behavior 47(1): 83-91. ISSN: 0018-506X.
NAL Call Number: QP801.H7H64
Descriptors: African elephant, Loxodonta africana, reproductive behavior, musth, characteristics, free ranging males, Kenya, temporal glands, secretions, glucocorticoid, urine dribbling, androgen levels, aggressive behavior.
Goodwin, T.E. and L.E.L. Rasmussen (2004). Collaborative research at the interface of chemistry and biology: development and identity of sexually dimorphic reproductive signals and responses by African elephants. Abstracts of Papers American Chemical Society 227(Part 1): U658. ISSN: 0065-7727.
NAL Call Number: 381 Am33PA
Descriptors: reproductive system, chemistry, biology, African elephants, research, reproductive signals.
Hollister Smith, J.A., J.H. Poole, E.A. Archie, E.A. Vance, N.J. Georgiadis, C.J. Moss, and S.C. Alberts (2007). Age, musth and paternity success in wild male African elephants, Loxodonta africana. Animal Behaviour 74(Part 2): 287-296. ISSN: 0003-3472; Online: 1095-8282.
Descriptors: African elephant, sexual activity, intrasexual selection, age-related paternity success, musth.
Ishengoma, D.R.S., A.M. Shedlock, C.A.H. Foley, L.J. Foley, S.K. Wasser, S.T. Balthazary, and B.M. Mutayoba (2008). Effects of poaching on bull mating success in a free ranging African elephant (Loxodonta africana) population in Tarangire National Park, Tanzania. Conservation Genetics 9(2): 247-255. ISSN: 1566-0621.
NAL Call Number: QH75.A1 C56
Abstract: Poaching and habitat encroachment for human settlement are the two major factors that caused contraction of elephant populations in Africa. While the effects of poaching on many aspects of elephant social systems have been studied, the impacts on mating patterns are not yet understood and such information is still lacking in most African countries. In this study, we used elephant specific-microsatellite DNA to generate genotypes from 86 elephant samples (84 fresh feces and two tissue samples) from Tarangire National Park (TNP), Tanzania to assess the mating success of individual males. We also tested whether the oldest bulls are more likely to sire most of the offspring in a severely poached population. Genetic paternity analysis was compared to behavioural observations of matings collected over a 3-year period (1998-2001) to determine the success of bull mating strategy. The genotypes of 26 infants, their known mothers and 10 out of 43 potential breeding bulls in TNP were used to assign 31% of the offspring at 80% confidence level to their potential fathers with simulation assuming that 23% (10/43) of the breeding males were sampled. Mating success of individual bull based on both behavioural and genetic data showed that the oldest remaining bulls performed most of the matings and fathered the majority of infants. We speculate that the lifetime fitness of bulls that have survived poaching may be elevated because their period of dominance increases.
Descriptors: African elephants, Loxodonta africana, DNA, poaching, bull mating success, microsatellite repeats, Tarangire National Park,Tanzania.
Jones, C.J., F.B. Wooding, S.S. Mathias, and W.R. Allen (2004). Fetomaternal glycosylation of early placentation events in the African elephant Loxodonta africana. Placenta 25(4): 308-20.
NAL Call Number: QP281.P53
Abstract: During implantation in the African elephant (Loxodonta africana), fetal trophoblast displaces the surface uterine epithelium and superficially penetrates the uterine glands. This limited invasion is followed by the upgrowth of blunt fingers of endometrial stroma, covered with trophoblast and containing capillaries that subsequently vascularize the growing placenta. We have used lectin histochemistry to compare the glycosylation of maternal endothelial cells in the endometrium with those growing within the trophoblastic processes of a 2 g embryo (approximately 125 days' gestation), and also examine changes in the endometrial glands associated with trophoblastic invasion. Maternal vessels at the apices of the trophoblast-covered stromal upgrowths showed increased expression of terminal N-acetyl galactosamine, N-acetyl glucosamine oligomers, some sialic acids, and tri/tetra-antennate non-bisected complex N-linked glycan, as indicated by increased lectin staining. The areas of increased staining were also more resistant to neuraminidase digestion. Invaded glands had distended walls composed of flattened epithelial cells, some of which showed heavy lectin staining suggestive of intracellular glycan accumulation. The vascular changes suggest that new maternal capillary growth is accompanied by alterations in surface glycosylation. This may be the result of increased glycosyl transferase activity associated with cell proliferation and may also indicate the expression of significantly increased anti-adhesive molecules preventing blood stasis and egress of maternal immunocompetent cells into the fetal compartment.
Descriptors: physiology, embryo implantation physiology, maternal fetal exchange physiology, trophoblasts metabolism, biological markers analysis, endometrium metabolism, gestational age, glycosylation, immunoenzyme techniques, lectins metabolism.
Meyer, J.M., S.L. Walker, E.W. Freeman, B.G. Steinetz, and J.L. Brown (2004). Species and fetal gender effects on the endocrinology of pregnancy in elephants. General and Comparative Endocrinology 138(3): 263-270.
NAL Call Number: 444.8 G28
Abstract: Quantitative and temporal progestin profiles vary during gestation in the elephant, sometimes making it difficult to determine if a pregnancy is progressing normally. The aim of the present study was to determine if circulating progestin variability was related to species or fetal gender effects. A similar comparison also was conducted for secretory profiles of prolactin, relaxin, and cortisol. Overall mean progestin concentrations during gestation in Asian (n = 19) and African (n = 8) elephants were similar; however, the temporal profiles differed (P < 0.001). Concentrations were higher in African elephants during the first half of pregnancy, but then declined to levels below those observed in Asian elephants (P < 0.05). There also was a fetal gender effect in Asian, but not African elephants. Progestin concentrations were higher in Asian cows carrying male calves (n = 9) as compared to those carrying females (n = 10) (P < 0.001). Overall prolactin concentrations were higher in Asian than in African elephants between 8 and 15 months of gestation ( P< 0.001). There were no species differences in the secretory patterns of relaxin. Cortisol was relatively stable until the end of gestation when significant surges were observed, mainly between 8 and 11 days before parturition, and again on the day of birth. In sum, a comparison of progestin patterns between Asian and African elephants identified notable differences related to species and fetal gender. A role for cortisol in the initiation of parturition also was inferred from these data. From a practical standpoint, understanding the factors affecting gestational hormone characteristics and recognizing what the species differences are will help ensure that data used in diagnosing and monitoring elephant pregnancies are properly interpreted.
Descriptors: blood, embryology, hydrocortisone in blood, maternal fetal exchange physiology, pregnancy, progestins in blood, analysis of variance, fetus, prolactin in blood, relaxin in blood, sex factors, species specificity.
Ortolani, A., K. Leong, L. Graham, and A. Savage (2005). Behavioral indices of estrus in a group of captive African elephants (Loxodonta africana). Zoo Biology 24(4): 311-329. ISSN: 0733-3188.
NAL Call Number: QL77.5.Z6
Descriptors: estrous cycle, sexual behavior, flehmen, estrus detection, males, females.
Osthoff, G., M. de Wit, A. Hugo, and B.I. Kamara (2007). Milk composition of three free ranging African elephant (Loxodonta africana africana) cows during mid lactation. Comparative Biochemistry and Physiology B, Biochemistry and Molecular Biology 148(1): 1-5. ISSN: (p) 1096-4959; (E) 1879-1107.
Descriptors: African elephant, Loxodonta africana, milk composition, carbohydrates, casein, fatty acids, lactation, lactose, lipids, milk fat, milk protein, oligosaccharides, whey protein.
Owens, M.J. and D. Owens (2009). Early age reproduction in female savanna elephants (Loxodonta africana) after severe poaching. African Journal of Ecology 47(2): 214-222. ISSN: 0141-6707.
NAL Call Number: 409.6 Ea7
Abstract: A 10-year study revealed that after severe poaching (>93% killed) of elephants (Loxodonta africana) in Zambia's North Luangwa National Park (NLNP) during the 1970s and 1980s, the age of reproduction in females was greatly reduced. Fifty-eight per cent of births were delivered by females aged 8.5-14 years, an age at which elephants were reported to be sexually immature in nearby South Luangwa National Park (SLNP) before poaching. The mean age of females at first birth (AFB) (1993, 1994) was 11.3 years. Prior to poaching, the mean age AFB in SLNP was 16 years. The NLNP age structure and sex ratio were skewed, mean family unit size was reduced, and 37% of family units contained no females older than 15 years. Twenty-eight per cent of family units were comprised entirely of a single mother and her calf, and 8% of units consisted only of orphans who would have been considered sexually immature prior to poaching. Only 6% of survivors were older than 20 years, the age at which females in little-poached populations generally become most reproductively active. After a community-based conservation programme and the UN-CITES ban on the ivory trade were introduced, no elephants were recorded killed. In spite of a high reproductive rate, 6 years after poaching decreased, the density of the NLNP population had not increased, supporting predictions that the removal of older matriarchs from family units will have serious consequences on the recovery of this species.
Descriptors: African elephant, Loxodonta africana, community based conservation, early age reproduction, ivory trade, ban, poaching, social dynamics.
Stumpf, P. and U. Welsch (2004). Secretory and defensive functions of the duct system of the lactating mammary gland of the African elephant (Loxodonta africana, Proboscidea). Zoomorphology (Berlin) 123(3): 155-167. ISSN: 0720-213X.
NAL Call Number: 442.8 Z33
Descriptors: African elephant, mammary gland, lactating, duct system, secretory, defensive functions, microorganisms, invading, IgA, lactation period.
Weissenbock, N.M., H.M. Schwammer, and T. Ruf (2009). Estrous synchrony in a group of African elephants (Loxodonta africana) under human care. Animal Reproduction Science 113(1/4): 322-327. ISSN: 0378-4320.
Descriptors: African elephant, Loxodonta africana, estrous synchrony, captive zoo animals, dominance hierarchy.
Wittemyer, G., H. Barner Rasmussen, and I. Douglas Hamilton (2007). Breeding phenology in relation to NDVI variability in free-ranging African elephant. Ecography 30(1): 42-50. ISSN: 0906-7590.
NAL Call Number: QH540.H6
Abstract: The phenology of reproduction is often correlated with resource availability and is hypothesized to be shaped by selective forces in order to maximize lifetime reproductive success. African elephants have the distinctive life history traits of a 22 month gestation and extended offspring investment, necessitating a long-term strategy of energy acquisition and reproductive expenditure to ensure successful offspring recruitment. We investigated the relationship between the reproductive phenology of a wild elephant population and resource availability using remotely sensed Normalized Differential Vegetation Index (NDVI) data as a measure of time-specific primary productivity and hence forage quality. The initiation of female elephants' 3+yr reproductive bout was dependent on conditions during the season of conception but timed so parturition occurred during the most likely periods of high primary productivity 22 months later. Thus, the probability of conception is linked to the stochastic variation in seasonal quality and the phenology of parturition is related to the predictable seasonality of primary productivity, indicating elephants integrate information on known current and expected future conditions when reproducing. Juvenile mortality was not correlated with ecological variability, hence female fecundity rather than calf mortality appears to drive demographic processes in the study population. Extreme climatic events, such as those associated with the El Nino-Southern-Oscillation (ENSO), acted to synchronize female fecundity in the population. This study suggests that the relationship between fecundity and ecological variability instigates the characteristic demographic fluctuations in elephant populations, rather than the mortality-driven fluctuations observed in many ungulate populations.
Descriptors: African elephant, Loxodonta africana, breeding phenology, free ranging, reproductive success.
Wooding, F.B., F. Stewart, S. Mathias, and W.R. Allen (2005). Placentation in the African elephant, Loxodonta africanus. III. Ultrastructural and functional features of the placenta. Placenta 26(6): 449-70.
NAL Call Number: QP281.P53
Abstract: Successful transfer of nutrients to the elephant fetus during pregnancy relies on a variety of placental modifications. Our light and electron microscopical investigations show that the structure is endotheliochorial from implantation to term, with unicellular, never syncytial trophoblast. Light and electron microscope immunocytochemistry shows the restriction of the glucose transporter 1 isoform to the basolateral surfaces of the trophoblast, with the glucose transporter 3 restricted to the apical plasmalemma of the trophoblast. Glucose transport to the fetus therefore requires a sequential use of both isoforms. Light and electron microscope cytochemistry indicate the presence of iron deposits only in the haemophagous zones confirming their iron transport function. No trophoblast areas with high concentrations of Calcium binding protein, specialised for Calcium transport were found. In situ hybridisation demonstrated the presence of IGF-II mRNA in the trophoblast from the earliest stage, with TGFbeta1 and HGF-SF mRNA expressed subsequently but only IGF-II and HGF mRNA present in the second half of pregnancy. The results are briefly discussed in terms of placental growth and function and indicate that the elephant placenta is another example of a unique solution to the variety of problems posed by a resident fetus.
Descriptors: physiology, placenta cytology, placenta physiology, pregnancy, calcium binding proteins metabolism, embryo implantation physiology, epidermal growth factor genetics, glucose transporter type 1, glucose transporter type 3, hepatocyte growth factor genetics, immunohistochemistry, in situ hybridization, insulin like growth factor II genetics, iron metabolism, keratin metabolism, microscopy, electron, monosaccharide transport proteins metabolism, nerve tissue proteins metabolism, proto oncogene proteins C met metabolism, transforming growth factor beta genetics, trophoblasts metabolism, trophoblasts ultrastructure.
Yon, L., S. Kanchanapangka, N. Chaiyabutr, S. Meepan, F.Z. Stanczyk, N. Dahl, and B. Lasley (2007). A longitudinal study of LH gonadal and adrenal steroids in four intact Asian bull elephants (Elephas maximus) and one castrate African bull (Loxodonta africana) during musth and non-musth periods. General and Comparative Endocrinology 151(3): 241-245. ISSN: 0016-6480; Online: 1095-6840.
Descriptors: African elephant, Loxodonta africana, Asian elephant, Elephas maximus, endocrine system, reproduction, castration, musth cycle.