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15 results on '"Cigler, Pia"'

2. Evidence for seasonal shift in the reproduction of Aldabra giant tortoises (Aldabrachelys gigantea) in managed care in the Northern hemisphere compared to the natural habitat in the Southern hemisphere.

Author

Cigler, Pia, Davis, Leyla R., Gmür, Sarah‐Lisa, Clauss, Marcus, Hatt, Jean‐Michel, Ohlerth, Stefanie, Mastromonaco, Gabriela, and Kummrow, Maya

Abstract

Ex situ breeding constitutes an important tool for species conservation; however, many reptile species are not managed sustainably under human care due to poor fecundity in ex situ settings. In this study, we tested whether the translocation of a seasonally reproducing species to a different environment results in decoupling of extrinsic signals and intrinsic conditions. The endocrinological patterns of plasma steroid sex hormones, follicular development, and mating behaviour of two female and two male sexually mature Aldabra tortoises (Aldabrachelys gigantea) in a zoological institution in the Northern hemisphere was aligned with enclosure climate data (mean monthly daylight duration, temperature, and precipitation) and compared with respective hormone patterns of wild individuals and climate conditions in the native habitat on the Aldabra Atoll in the Southern hemisphere. Whereas occurrence of mating behaviour was not considered a limiting factor, lack of ovulation and subsequent follicular atresia was the main reason for the lack of reproductive output. While it was impossible to elucidate the triggering factors of ovulation and the multifactorial complexity of reproduction was not fully addressed, this study indicates suboptimal temperature conditions and relative temporal shifts of interacting external triggers (temperature and photoperiod) in the zoo setting. [ABSTRACT FROM AUTHOR]

Published
2024
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3. Morphological evidence for the physiological nature of follicular atresia in veiled chameleons (Chamaeleo calyptratus)

Author

Dervas, Eva; https://orcid.org/0000-0002-7308-9216, Cigler, Pia, Hatt, Jean-Michel; https://orcid.org/0000-0002-7043-7430, Kummrow, Maya S; https://orcid.org/0000-0002-5343-1336, Dervas, Eva; https://orcid.org/0000-0002-7308-9216, Cigler, Pia, Hatt, Jean-Michel; https://orcid.org/0000-0002-7043-7430, and Kummrow, Maya S; https://orcid.org/0000-0002-5343-1336

Abstract

Follicular atresia (FA) has been assumed to serve different functions in reptiles, e.g. helping to develop hierarchies, limiting clutch size, and regression of ovarian structures. Reproductive output is dependent on a balance between ovulations and FA. Excessive rates of FA may not only be detrimental for the survival of a population, but have also been associated with pathological conditions. In order to gain insights into the physiological and potentially pathological processes of FA, we performed a decriptive study on the morphological features of the ovaries in sexually mature female veiled chameleons (Chamaeleo calyptratus, VC). Of 60 clinically healthy female VC with continuous ovarian cycling and at least one confirmed cycle with FA over at least 1.5 years, 30 were selected for macroscopic evaluation of ovarian appearance and 7 were subjected to histology and immunohistology. While FA of previtellogenic follicles happened at a low rate, expected for a species with two germinal beds per ovary and polyautochronic reproductive pattern, atresia in the late vitellogenic stage affected entire generations of follicles, consequential to ovulatory failure. Histologically, no pathological processes were identified in any of the animals. Rather, three stages of FA (early, middle, late) were defined and vitellogenic follicles showed two distinct morphological types of FA: yolky and cystic. Yolky FA was found in 21/30 (70%) animals, while cystic FA co-occurred in 9/30 (30%) of the animals.

Published
2024

15. Reptilian Skin and Its Special Histological Structures

Author

Kubale, Valentina, Rutland, Catrin Sian, and Cigler, Pia

Subjects
Medical / Veterinary Medicine
Abstract

Reptilian skin is covered with scales forming armor that makes it watertight and enables reptiles to live on land in contrast to amphibians. An important part of the skin is the horny epidermis, with thick stratum corneum in which waxes are arranged in membrane-like layers. In lizards and snakes, the whole skin is covered in overlapping epidermal scales and in turtles and crocodiles in dermal scutes. The cornified part of the epidermis is strengthened by β-keratin and sometimes α-keratin. In crocodiles and many turtles, the outer scale surface consists of β-keratin and the hinge region containing α-keratin. In lizards and snakes, both keratins form continuous layers with the α-keratin below the β-keratin. Some reptiles have developed a sensitive mechanosensory system in the skin. The colors of reptile skin are produced by melanocytes and three types of chromatophores: melanophores, xanthophores, and iridophores. The color patterns may be fixed or the chromatophores may provide rapid color change. Skin from different species of reptiles, turtles (red-eared slider (Trachemys scripta elegans)), snakes (Emerald tree boa (Corallus caninus) and Burmese python (Python bivittatus)), Cuvier’s dwarf caiman (Paleosuchus palpebrosus), lizards (Leopard Gecko (Eublepharis macularius)), and Green iguana (Iguana iguana), were examined with histology techniques and compared.

Published
2020

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