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Morphometrics and the Ultrasonographic Ovarian Appearance of Sexually Mature Female Bornean Earless Monitor Lizards ( Lanthanotus borneensis )
Abstract
There is a lack of reproductive information regarding the endangered Bornean earless monitor (Lanthanotus borneensis), including on how to determine its sex. The objective of this study was to identify sex in a zoo population of 10 healthy Bornean earless monitors, as well as define the ultrasonographic appearance of sexually mature female ovaries. Morphometrics of this population, including snout-vent length (SVL), tail length (TL), head length (HL), head width (HW), head height (HH), length of the dentary (DL), dentary height (DH), and lower jaw width (LJW) were recorded. In addition, coelomic ultrasounds under manual restraint were performed. Total follicles per animal, 7.55 ± 2.06 (mean ± SD), follicular volume, 0.32 ± 0.20 (cm3) (mean ± SD), and type of follicles (hypoechoic, vitellogenic and laminar) were recorded for each female in the study population. While morphometrics were not useful in determining sex, ultrasound was a reliable, non-invasive method for this species. Additionally, baseline measurements regarding their ovarian morphology were determined, which may be useful for future breeding and health assessments for this endangered species.
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Lanthanotus borneensis , the Bornean earless monitor, is a monotypic member of the family Lanthanotidae, and restricted to the island of Borneo. Little has been published on its field ecology. This study investigated aspects of its thermal biology through an analysis of surface body temperatures of free ranging individuals against corresponding environmental temperatures, in order to explore aspects of microhabitat utilisation in relation to thermoregulation. A generalised linear mixed model shows significant effect of air and substrate temperatures, but not of water temperature. Further, the fixed effects of substrate temperature (coefficient estimate 0.396; ) versus ambient temperature (0.264; ), is suggestive of thigmothermy as the primary mode of thermoregulation. The species does not appear to utilise specific microhabitat structures to thermoregulate, the results of these observations suggesting that it is a thermoconformer.
Being endemic to Borneo, the Earless monitor, Lanthanotus borneensis (Steindachner, 1878) is rarely found in its habitats due to its cryptic behavior. We provide care for confiscated animals in the Reptile House of Museum Zoologicum Bogoriense (MZB) in Cibinong, West Java, Indonesia since 2014. Little is known on its natural prey but from scattered descriptive reports. This study is aimed at documenting the feeding behavior of ten captive Earless monitors and events of predation on frogs. We set up two experiments, one with meat of Rice Field Frog, Fejervarya limnocharis, and the other with live frog of the same species. Our recorded observations ran for four weeks for the frog meat feeding experiment and followed by the frog predation experiment. Our results showed that lizards constantly accepted frog meat. Lizards tended to feed before sunset for a short period of time on the muddy soil surface, although a few individuals inconsistently fed under water. The average body mass for these lizards increased by 4.29 g and average SVL by 0.45 cm. We recorded predation on frogs in three out of ten individuals observed during this study. If F. limnocharis is confirmed to occur in the natural habitats of L. borneensis, it is possible that this frog species is among the natural prey for Earless monitors. Further studies on its natural diets should be conducted to gain in-depth knowledge essential for generating effective captive husbandry for this nationally protected species in Indonesia.
Being endemic to Borneo, the Earless monitor, Lanthanotus borneensis (Steindachner, 1878) is rarely found in its habitats due to its cryptic behavior. We provide care for confiscated animals in the Reptile House of Museum Zoologicum Bogoriense (MZB) in Cibinong, West Java, Indonesia since 2014. Little is known on its natural prey but from scattered descriptive reports. This study is aimed at documenting the feeding behavior of ten captive Earless monitors and events of predation on frogs. We set up two experiments, one with meat of Rice Field Frog, Fejervarya limnocharis, and the other with live frog of the same species. Our recorded observations ran for four weeks for the frog meat feeding experiment and followed by the frog predation experiment. Our results showed that lizards constantly accepted frog meat. Lizards tended to feed before sunset for a short period of time on the muddy soil surface, although a few individuals inconsistently fed under water. The average body mass for these lizards increased by 4.29 g and average SVL by 0.45 cm. We recorded predation on frogs in three out of ten individuals observed during this study. If F. limnocharis is confirmed to occur in the natural habitats of L. borneensis, it is possible that this frog species is among the natural prey for Earless monitors. Further studies on its natural diets should be conducted to gain in-depth knowledge essential for generating effective captive husbandry for this nationally protected species in Indonesia.
Biodiversity loss is the greatest environmental problem threatening ecosystem, animal, and human health. Anthropogenic induced changes to climate, habitat, disease, species distributions, poaching, and unsustainable trade have accelerated extinction rates in all vertebrates, including reptiles. Preventing reptile extinctions will require humans to acknowledge these losses and develop ex situ and in situ plans to preserve them. Assisted reproductive technologies (ART) are management tools used to protect numerous vertebrate taxa; however, progress in developing ART for reptiles has lagged. Creating functional and sustainable reptile ART will strengthen our conservation capacity by capturing genetic material from select individuals to overcome natural or manmade boundaries. Utilising short-term gamete storage and genome resource banking, in conjunction with timed artificial insemination (AI) or ex ovo incubation, could lead to profound advances in reptile conservation, mitigating the loss of reptile biodiversity. In this article, we review ART reptile research completed since the 1970s. Topics include AI, hormonal control of reproduction, gamete collection, gamete storage, and genome resource banking. Additionally, we review the potential application of advanced reproductive methodologies, including in vitro/ex ovo fertilisation, intracytoplasmic sperm injection, cloning (somatic cell nuclear transfer), and genetic editing.
Life history theory predicts that there should be an inverse relationship between offspring size and number, because individuals cannot simultaneously maximize both when resources are limited. Although extensively studied in avian species, the occurrence and determinants of reproductive tradeoffs in oviparous reptiles are far less understood, particularly in parthenogenetic species. We studied this trade-off in the Colorado Checkered Whiptail, Aspidoscelis neotesselatus, a female-only parthenogenetic lizard. Using data previously collected in 2018 and 2019, we tested for clutch and egg size trade-offs and determined whether this relationship could be influenced by female size and aspects of physiological condition. Physiological condition included energy-mobilizing hormone (i.e. corticosterone ‘CORT’), oxidative stress (i.e. reactive oxygen metabolites ‘ROMs’), and innate immune function (bacterial killing ability ‘BKA’). We found the effect of clutch size on follicle size was significant, but not linear. Specifically, follicle size was on average larger in females with clutches of two follicles when compared to clutches of one follicle, but smaller in females with clutches of three when compared to clutches of two. In addition, females that were larger produced larger follicles regardless of clutch size. Neither CORT nor BKA affected the relationship between follicle size and clutch size. However, ROMs did explain variability in this relationship: oxidative stress was more elevated in females that produced larger clutches and larger follicles. We conclude that clutch size and body size are key life history traits that shape follicle size, and that investments into larger clutches and follicle size come at the cost of oxidative damage.
Starting in 2014, members of the European Association of Zoos and Aquariums (EAZA) began to acquire earless monitor lizards. In this paper, the focus is on the ex situ population of Lanthanotus borneensis in EAZA, its origin, current status, role and perspectives.
Follicular dynamics of Tupinambis merianae lizards was analyzed by means of ultrasound examination and radio frequency identification, during three consecutive reproductive periods, both in reproduction and in sexual isolation. Series of follicular development which ended in ovulation, and series of follicular development without ovulation, followed by a regression process, were observed, as well as a combination of both. Ovulation was found to be strongly dependent on mating con-summation. In 34% of the cases in which follicular development ended with ovula-tion, and hence oviposition, follicles showed a steady and uniform growth up to the periovulatory period, also acquiring a mild echogenicity. In the absence of ovulation (66% of cases), follicular development showed two patterns: a short and a long-term anovulatory follicular cycle. In the first pattern, follicles showed limited growth and a non-echoic aspect, which suggests a previtellogenic condition. In the second pattern, follicles exhibited a growth and echogenicity similar to periovulatory ones, presumably attaining a vitellogenic stage. In addition, follicular development in reproducing females was superior to that of sexually isolated females. Follicular development, ovulation, and follicular regression appeared to constitute generalized events affecting most, if not all, of the recruited follicles.
The application of cytochrome oxidase subunit I for genetic divergence and phylogenetic analyses in monitor lizards seems to be limited, despite the practicality and relevance to use the short sequence of this region known as the DNA barcode. Some Indonesian species of monitor lizards are morphologically similar, some of which are legally exported as pet animal commodities and some others being protected by Indonesian national law. Thus, a practical molecular tool that can be useful to help clarify their species identity is essential, especially for closely related species. This study used the DNA barcode to test the application of this mitochondrial DNA region as a molecular tool to identify some species of Indonesian monitor lizards for the first time. Results showed that the Barcodes can facilitate molecular species identification based on their relative amount of genetic divergence and phylogenetic relationships. Closely related species can be distinguished based on the short sequences, as well as a likelihood of species misidentification among samples in this study. Further study should be performed in the future using more species, especially those belong to groups of species complex from the eastern Indonesia and species protected by the Indonesian national law.
A short assessment of the behavior, habitat and habitat use of the sole member of its monotypic family, the Earless Monitor lizard Lanthanotus borneensis was undertaken for the first time. Field data of this important species were lacking for more than a century since its description in 1878. Nearly nothing is known about life history or even its natural habitat. The only previously known facts were taken from a few captive animals held in the early 60s and 70s of the last century. Metric data of size, weight, body temperature, and sex ratio of 19 individuals were examined. Natural food items were identified. The population structure of a subpopulation was estimated. A brief survey of the additional herpetofauna is given for the area.
The following paper presents the first published record of the cryptic Borneo Earless Monitor (Lanthanotus borneensis Steindachner, 1877) from West Kalimantan (Indonesian Borneo). This sole member of the family Lanthanotidae is endemic to Borneo. Since its description in 1877, all locality records of specimens refer to Sarawak (Malaysian Borneo). The recent discovery of this “living fossil” in an oil palm estate under development in Landak District expands its known distribution southward to Kalimantan. This paper (i) describes the circumstances of the discovery, characteristics of the individual and microhabitat structure in which it was found, (ii) provides results from local community interviews about the local distribution of the species, suggesting it is found more broadly in the Landak District and possibly elsewhere, and (iii) places this information in a broader context of current knowledge and high conservation value of L. borneensis.
Varanoidea is a monophyletic group of anguimorph lizards, comprising the New World helodermatids, the Bornean earless monitor Lanthanotus borneensis, and the Old World monitors (Varanus). I use mitochondrial DNA sequences and extensive taxonomic sampling to test alternative hypotheses of varanoid relationships. The most parsimonious hypothesis confirms the monophyly of Varanoidea (Heloderma, Lanthanotus, and Varanus) and Varanus, as well as the sister-taxon relationship of Varanus and Lanthanotus. The relationships among Varanus species differ in several respects from previous hypotheses. Three major lineages are recognized within Varanus: an African clade basal to the rest of the group, an Indo-Asian clade, and an Indo-Australian clade. Within the last lineage, the endemic Australian dwarf monitors (Odatria) form a clade sister to the large Australian monitors (the gouldii group). Tests of the effects of rate heterogeneity and homoplasy demonstrate that putative process partitions of data are largely congruent with one another and contribute positive support to the overall hypothesis. (C) 2001 The With Hennig Society.
Varanid lizards are difficult to sex in the field because commonly used techniques are not completely reliable and definitive techniques are not logistically or economically feasible for many field-based applications. Previous work has shown that variation in morphometric variables can be used to determine sex in some species of varanid. Here we build on these previous exploratory analyses by developing a set of a priori models (containing morphometric variables) to predict the sex of six species of Australian varanid, and then examining their relative support under the information-theoretic framework. We then use cross-validation procedures to determine the reliability of the best-supported models' predictive ability. Our analysis suggests that a large sample size is required for building models to predict sex in many species. The most important sexually diagnostic features for many species were a number of head variables and (to a lesser extent) scaling of limb proportions. This analysis provides some useful statistical tools for the field-sexing of adult and juvenile Varanus gouldii with a known level of reliability and also serves to highlight the danger of extrapolating from potentially spurious results when using exploratory methods or null hypothesis testing.
Follicular dynamics of Tupinambis merianae lizards was analyzed by means of ultrasound examination and radio frequency identification, during three con-secutive reproductive periods, both in reproduction and in sexual isolation. Series of follicular development which ended in ovulation, and series of follicular develop-ment without ovulation, followed by a regression process, were observed, as well as a combination of both. Ovulation was found to be strongly dependent on mating con-summation. In 34% of the cases in which follicular development ended with ovula-tion, and hence oviposition, follicles showed a steady and uniform growth up to the periovulatory period, also acquiring a mild echogenicity. In the absence of ovulation (66% of cases), follicular development showed two patterns: a short and a long-term anovulatory follicular cycle. In the first pattern, follicles showed limited growth and a non-echoic aspect, which suggests a previtellogenic condition. In the second pattern, follicles exhibited a growth and echogenicity similar to periovulatory ones, presum-ably attaining a vitellogenic stage. In addition, follicular development in reproduc-ing females was superior to that of sexually isolated females. Follicular development, ovulation, and follicular regression appeared to constitute generalized events affecting most, if not all, of the recruited follicles.
Sex determination in reptiles is important for implementing appropriate husbandry, successful pairing for breeding programs, and reproductive medical care. In reptile species that are not sexually dimorphic, accuracy in sex determination is dependent upon methods other than physical observation. Preferred sexing techniques should be quick, noninvasive, and reliable, and they should be able to be performed by veterinarians with a broad range of reptile experience. Vast anatomical differences among reptiles make the efficacy of these techniques highly variable between species. This study evaluated hemipenis contrast radiography and computed tomography techniques, previously described in other Heloderma species, to determine reliability in sexing 23 Gila monsters (Heloderma suspectum). The results were compared to the sex determined by coelomic ultrasound, which indicated that there were 8 females and 15 males. Identification of hemipenes in males was shown in 1/15 (7%) by contrast radiography and 9/15 (60%) by hemipenis contrast computed tomography. Outline of the cloacal rim in females was seen in 100% (8/8) by contrast radiography and 100% (8/8) by contrast computed tomography. Our findings suggest that contrast radiography and computed tomography are not reliable methods for sex determination in Gila monsters, and that coelomic ultrasound is currently the most reliable, noninvasive technique for this species.
Sejak pertama kali ditemukan pada tahun 1878 hingga saat ini lebih dari 200 ekor Lanthanotus borneensis yang telah ditemukan. Lanthanotus borneensis hanya tersebar di Kalimantan dan Sarawak. Namun dari banyaknya individu yang ada, data morfometri masih kurang diketahui. Artikel-artikel yang memiliki data ukuran tubuh dan awetan yang ada di Museum Zoologicum Bogoriense diukur, untuk mengetahui morfometrinya yaitu, panjang tubuh (SVL), panjang ekor (TaL), panjang total (TL) dan lebar kepala (HW) dari biawak Kalimantan yang ada. Hasil analisis menunjukan bahwa ukuran tubuh individu biawak yang ditemukan Kalimantan relative lebih besar jika dibandingkan dengan yang ditemukan di Sarawak serta memiliki ukuran lebar kepala 2,1 ± 1,0 mm.
Fitness theory attempts to explain how organisms survive by understanding not survival as such but the design that confers the highest survival. This study investigated the effects of phenotypic variation on the reproductive strategy (clutch and egg size) of loggerhead and leatherback sea turtles as well as the influence of size on hatchling fitness traits. We examined whether larger females produced larger hatchlings of higher fitness by testing two hypotheses; the optimal egg size theory, and the bigger is better hypothesis. The study investigated how maternal length influences reproductive output (clutch size, egg size), and how hatchling morphology affects their performance. Hatchling performance was analysed by measuring two correlates of fitness, crawling and swimming speeds, as these two traits positively influence their survival by minimising the time of exposure in highly predated areas. The reproductive strategy of both loggerhead and leatherback turtles nesting in South Africa was found to support the optimal egg size theory whereby larger turtles produce larger clutches but not larger eggs. Egg size was constant irrespective of maternal length. The low contribution of female body size to clutch size variability suggests that other factors are affecting female reproductive output during a nesting season. Hatchling fitness assessment trials demonstrated that hatchlings with longer carapaces and flippers lengths swam faster. This adds to the growing body of evidence suggesting that larger hatchlings are more likely to survive because they spend less time in high predation risks areas (i.e. beach and nearshore) and thus assumed fitter than smaller ones. These findings have implications for overall population growth/recovery if smaller hatchlings of lower fitness are produced and have decreased dispersal abilities and thus lower likelihood of survival.
The first reliable information regarding successful long term captive husbandry and breeding of Kalimantan Earless Monitor, Lanthanotus borneensis (Steindachner, 1878) at Moscow Zoo is presented.
Varanid lizards, which vary considerably in body mass both interspecifically and intraspecifically, are generally considered to be morphologically similar. However, significant and non-isometric variation in the relative appendage dimensions for 17 species of Western Australian goannas suggest that these lizards are not morphologically conservative. The first and second canonical variates clearly distinguish the two subgeneral Odatria and Varanus, and species are generally sexually dimorphic. The morphological variation observed among these 17 species of goanna is associated with foraging mode and ecology. However, no single or small group of morphological dimensions discriminates phylogenetic groups, sexes, or ecological groups, and body size is an important component in these analyses. J. Morphol. 233:127-152, 1997. © 1997 Wiley-Liss, Inc.
An understanding of normal reptilian anatomy and physiology is required when diagnosing and treating disorders of the reptile reproductive tract. The wide variation in anatomy, physiology and reproductive strategies across the various taxonomic groups presents the clinician with challenges. This chapter outlines clinically relevant aspects of reptile reproductive anatomy and physiology including gender assessment, breeding management, oviposition/parturition, egg incubation and monitoring, and causes of embryonic mortality.
Sixteen adult white-throated monitors (Varanus albigularis), three Gila monsters (Heloderma suspectum), and 10 Mexican beaded lizards (H. horridum) of known sex were given ultrasound examinations to determine the value of two-dimensional ultrasound imaging technology for the purpose of determining sex in monomorphic lizards. Each animal in the study was examined only once. In every case, the sexes of V. albigularis and H. suspectum were correctly determined by abdominal ultrasound imaging. Images of three of the 10 H. horridum were not adequate for sex determination because of excessive bowel gas, which impeded ultrasound imaging. The sexes of the remaining seven H. horridum were correctly determined using abdominal ultrasound imaging. To confirm ultrasound determination, the sexes of the male H. horridum and H. suspectum were confirmed by digital hemipenis eversion immediately after the ultrasound procedure. The results clearly reveal that two-dimensional ultrasound imaging is useful for determining the sex of mature white-throated monitors and heloderms.
Germinal bed (GB) number in ovaries of 26 lizard species is described. This information, along with previous data on 14 other lizards, allowed us to form the following hypotheses concerning the relationships of GB number and (1) the numbers of growing and atretic follicles in the preovulatory ovary, (2) instantaneous fecundity, (3) geographic distribution, and (4) taxonomic relationship. Germinal bed number can vary within a family, but may be consistent within other families and also within genera. The 11 species with one GB per ovary are tropical or subtropical, or are derived from a primarily tropical genus, and exhibit a relatively low instantaneous fecundity (usually 1 egg). In contrast, all but one of the 21 temperate species examined have two GBs per ovary, but some tropical or subtropical species also exhibit this ovarian condition. Presence of two GBs per ovary is related to a wide range of instantaneous fecundities. In these species, rates of follicular atresia in preovulatory ovaries are inversely proportional to instantaneous fecundity. Species with one GB per ovary have not readily evolved new forms with higher instantaneous fecundities in the past. In contrast, the condition of two (or several) GBs per ovary has been associated with greater phylogenetic flexibility of instantaneous fecundity. In the latter species, evolutionary changes in pituitary FSH secretion, which affect both the number of ovarian follicles and rates of follicular atresia, may have mediated changes in instantaneous fecundity. Testing of these hypotheses must await more data on the number of GBs and growing and atretic follicles in preovulatory ovaries of more lizard species.
Gray-scale ultrasonic imaging (UI) was introduced in 1980 and initially was used to examine clinically the reproductive tract of mares. By 1983 in mares and 1984 in heifers/cows, UI had become a tool for basic research. In each species, transrectal gray-scale UI has been used extensively to characterize follicle dynamics and investigate the gonadotropic control and hormonal role of the follicles. However, the use of transrectal UI has also disclosed and characterized many other aspects of reproduction in each species, including (1) endometrial echotexture as a biological indicator of circulating estradiol concentrations, (2) relative location of the genital tubercle for fetal gender diagnosis by Days 50 to 60, and (3) timing of follicle evacuation during ovulation. Discoveries in mares include (1) embryo mobility wherein the spherical conceptus (6–16 mm) travels to all parts of the uterus on Days 11 to 15, (2) how one embryo of a twin set eliminates the other without self-inflicted damage, and (3) serration of the granulosum of the preovulatory follicle opposite to the future rupture site as an indicator of imminent ovulation. Studies with color-Doppler UI have shown that vascular perfusion of the endometrium follows the equine embryo back and forth between uterine horns and follows the expansion of the bovine allantochorion throughout each horn. In heifers, blood flow in the CL increases during the ascending portion of an individual pulse of PGF2α metabolite and then decreases. These examples highlight the power of UI in reproduction research. Without UI, it is likely that these and many other findings would still be unknown.
In monitor lizards, males are typically larger than conspecific females, but body shape is usually quite similar in both sexes. This not only represents a puzzle worthy of evolutionary explanation, but also makes field sex determination of monitor lizards difficult. We asked whether subtle differences in body shape follow the same pattern as in other sexually dimorphic lizard taxa and thus can be explained by the same selective forces. We tested the hypotheses that (1) females have a longer abdomen due to fecundity selection and (2) males possess bigger heads due to intrasexual selection. We also hypothesised that (3) male monitors show a wider chests and longer upper fore-limbs to win male-male wrestling matches. We monitored ontogeny in 35 mangrove-dwelling monitors (Varanus indicus). Seventeen body measurements were taken every three months up to the age of 24-34 months. Sex was determined by an ultrasonographic imaging. We employed multiple approaches to remove the effect of size and used both confirmation and exploratory statistics. The results revealed that sexual differences in body shape were small and emerged after maturity. Females have a relatively longer abdomen while males wider chest and longer upper fore-limbs. Thus, the differences in body shape between male and female varanid lizards may be attributed to both fecundity and sexual selection.
Six yearling Komodo dragons (Varanus komodoensis) underwent ultrasound examinations every three months over a nine-month period to assess the value of two-dimensional ultrasound imaging technology for the purpose of determining gender in this highly monomorphic species. Beginning at an age of 28 months, ovarian structures could be imaged, allowing a prediction of gender based on the presence or absence of ovarian follicles. Simultaneously, plasma testosterone concentration was measured monthly on each individual during the study period. Beginning at an age of 24 months, putative males had consistently elevated plasma testosterone values that were ∼40–60 times greater than those of putative females. In a blind comparison, predictions of gender based on plasma testosterone values matched the prediction of sex based on ultrasound imaging for all six individuals. The results indicate that measurements of circulating testosterone and two-dimensional ultrasound imaging together appear useful in the noninvasive determination of gender in juvenile V. komodoensis at just over two years of age.
It is unusual for seasonal breeders to frequently skip opportunities for reproduction. We investigated the relationship between physiological state and reproductive decision-making in Galápagos marine iguanas (Amblyrhynchus cristatus), a species in which females typically reproduce biennially, although the proportion of breeding individuals varies significantly across years. Nearly all adult-sized females initiated follicular development prior to the lekking period, but 38% of females resorbed all developing follicles 5–15 days before the start of copulations. Receptive and non-receptive females differed in reproductive hormones during the mate choice period. Testosterone peaked in receptive females immediately prior to copulation, indicating that testosterone or its derivative estradiol likely mediates female receptivity in Galápagos marine iguanas. Non-receptive females showed significant peaks in both testosterone and progesterone during follicular atresia, suggesting that these hormones may be involved in inhibiting vitellogenesis. Two to three weeks prior to the period of reproductive decision-making (and the onset of follicular atresia in non-receptive females) receptive females were in higher body condition, were developing larger follicles, and had lower levels of both baseline and stress-induced corticosterone. Reproduction is extremely costly in this long-lived species, and increases the likelihood of mortality in the year following breeding; females could therefore gain significant benefits from being attuned to indicators of reproductive success. We suggest that corticosterone may modulate reproductive decisions by altering individual sensitivity to both internal and external cues of the likelihood of successful reproduction.
Ultrasound imaging in reproductive sciences offers new opportunities regarding optimization of the induction of the sexual cycle and ovulation, superovulation regimes, contraception programs, semen collection and testicular sperm extraction techniques, ovum pick up and ovarian transplantation procedures, as well as the application of artificial insemination, embryo collection and transfer. In non-domestic species, most of which lack basic data, ultrasonography is an ideal tool to study reproductive biology in both captive and wild populations. The use of this imaging modality led us to develop new, or modify established, reproductive technologies. Ultrasonography has been an integral part of over 200 assisted reproduction procedures in 17 mammalian species performed by our research team between 1992 and 1999. These procedures included the initial characterization of sexual cycles, hormonal cycle induction, semen collection by electroejaculation or manual stimulation, non-surgical artificial insemination (AI), non-surgical embryo transfer and temporary hormonal contraception. For these investigations, a variety of newly developed equipment was applied and species-specific hormonal treatments designed. We used several commercial and customized ultrasound systems with a variety of technical features. Some relevant improvements of these applications will be described and the role of ultrasonography elucidated to.
Comparative diagnostic imaging of the reproductive tract in monitors: radiology - ultrasonography - coelioscopy
- Bj Schildger
- Tenhu
- Kramer
Captive maintenance and the first reproduction of Borneo earless monitors
- T Shirawa
- S Bacchini
- Shirawa
Female reproductive strategy of common water monitor (Varanus salvator) from Riau region
- S C Setyawatiningsih
- D D Solihin
- W Manalu
- A Boediono
- A Winarto
- Setyawatiningsih
Ultrasonic examination and anatomy of monitors (Varanus gouldii, V. indicus and V. griseus) (Sauria: Varanidae)
- H Tenhu
- B Schildger
- G Kuchling
- G Thompson
- Tenhu
Reptile Medicine and Surgery in Clinical Practice
- Tj
- Portas
The IUCN Red List of Threatened Species 2021
- I Das
- M Auliya
Beobachtungen an Taubwaranen (Lanthanotus borneensis) im Terrarium
- Mertens
Ultrasound features of the kidneys, urinary bladder, ovarian follicles and vaginal sacs of female water monitor lizard (Varanus marmoratus, Weigmann, 1834)
- R B Prades
- E A Lastica
- J A Acorda
- Prades
Comparative diagnostic imaging of the reproductive tract in monitors: radiology - ultrasonography - coelioscopy
- B J Schildger
- H Tenhu
- M Kramer
- M Gerwing
- G Kuchling
- G G Thompson
- R Wicker
- Schildger
Anmerkungen zur Haltung und Nachzucht des Taubwarans
- M Zollweg
- R Seipp
- Zollweg