Skin of the Cretaceous mosasaur Plotosaurus: implications for aquatic adaptations in giant marine reptiles

The physical nature of water and the environment it presents to an organism have long been recognized as important constraints on aquatic adaptation and evolution. Little is known about the dermal cover of mosasauroids (a group of secondarily aquatic reptiles that occupied a wide array of predatory niches in the Cretaceous marine ecosystems 92–65 Myr ago), a lack of information that has hindered inferences about the nature and level of their aquatic adaptations. A newly discovered Plotosaurus skeleton with integument preserved in three dimensions represents not only the first documented squamation in a mosasaurine mosasaur but also the first record of skin in an advanced member of the Mosasauroidea. The dermal cover comprises keeled and possibly osteoderm-reinforced scales that presumably contributed to an anterior–posterior channelling of the water flow and a reduction of microturbulent burst activities along the surface of the skin. Thus, hydrodynamic requirements of life in the water might have influenced the evolution of multiple-keeled body scales in advanced mosasauroids.     

First successful artificial insemination with frozen-thawed semen in rhinoceros

The first successful artificial insemination (AI) in a rhinoceros was reported in 2007 using fresh semen. Following that success, we decided to evaluate the possibility of using frozen-thawed semen for artificial insemination. Semen, collected from a 35-36 year old Southern white rhinoceros (Ceratotherium simum simum) in the UK was frozen using the directional freezing technique. This frozen semen was used in two intrauterine AI attempts on a 30 years old female rhinoceros in Hungary. The first attempt, conducted 30 days postpartum with an insemination dose of ∼135 × 10⁶ motile cells, failed. The second attempt, conducted two estrus cycles later with an insemination dose of ∼500 × 10⁶ motile cells, resulted in pregnancy and the birth of a healthy offspring. This represents the first successful AI using frozen-thawed semen in a rhinoceros, putting it among very few wildlife species in which AI with frozen-thawed semen resulted in a live birth. The incorporation of AI with frozen-thawed semen into the assisted reproduction toolbox opens the way to preserve and transport semen between distant individuals in captivity or between wild and captive populations, without the need to transport stressed or potentially disease carrying animals. In addition, cryopreserved spermatozoa, in combination with AI, are useful methods to extend the reproductive lifespan of individuals beyond their biological lifespan and an important tool for managing genetic diversity in these endangered mammals.     

Armored with skin and bone: A combined histological and μCT-study of the exceptional integument of the Antsingy leaf chameleon Brookesia perarmata (Angel, 1933)

Madagascar's endemic ground-dwelling leaf chameleons (Brookesiinae: Brookesia Gray, 1865 + Palleon Glaw, et al., Salamandra, 2013, 49, pp. 237–238) form the sister taxon to all other chameleons (i.e., the Chamaeleoninae). They possess a limited ability of color change, a rather dull coloration, and a nonprehensile tail assisting locomotion in the leaf litter on the forest floor. Most Brookesia species can readily be recognized by peculiar spiky dorsolateral projections (“Rückensäge”), which are caused by an aberrant vertebral structure and might function as body armor to prevent predation. In addition to a pronounced Rückensäge, the Antsingy leaf chameleon Brookesia perarmata (Angel, 1933) exhibits conspicuous, acuminate tubercle scales on the lateral flanks and extremities, thereby considerably enhancing the overall armored appearance. Such structures are exceptional within the Chamaeleonidae and despite an appreciable interest in the integument of chameleons in general, the morphology of these integumentary elements remains shrouded in mystery. Using various conventional and petrographic histological approaches combined with μCT-imaging, we reveal that the tubercle scales consist of osseous, multicusped cores that are embedded within the dermis. Based on this, they consequently can be interpreted as osteoderms, which to the best of our knowledge is the first record of such for the entire Chamaeleonidae and only the second one for the entire clade Iguania. The combination of certain aspects of tissue composition (especially the presence of large, interconnected, and marrow-filled cavities) together with the precise location within the dermis (being completely enveloped by the stratum superficiale), however, discriminate the osteoderms of B. perarmata from those known for all other lepidosaurs.     

The bone histology of osteoderms in temnospondyl amphibians and in the chroniosuchian Bystrowiella

Witzmann, F. and Soler-Gijón, R. 2010. The bone histology of osteoderms in temnospondyl amphibians and in the chroniosuchian Bystrowiella . — Acta Zoologica (Stockholm) 91 : 96–114
Bone histology of osteoderms in the armoured temnospondyl Peltobatrachus , plagiosaurids ( Gerrothorax , Plagiosuchus ) and dissorophids ( Aspidosaurus , Cacops , Platyhystrix ), as well as in the chroniosuchian Bystrowiella , is studied. The massive osteoderms of Peltobatrachus and Gerrothorax consist of homogeneous parallel-fibred bone, whereas in dissorophids, a lightly built, trabecular middle region is mantled by a thin cortex that is composed of a plywood-type structure. In Bystrowiella and Plagiosuchus , the osteoderms consist to a large degree of interwoven primary fibres and have cell lacunae that bear stumpy canaliculi. The differences in the histological structure of dissorophids and plagiosaurids suggest an iterative evolution of osteoderms. Furthermore, histology in Plagiosuchus indicates a metaplastic development of the osteoderms, whereas the osteoderms of Gerrothorax represent periosteal ossifications as in dissorophids. This suggests a convergent origin of osteoderms also within plagiosaurids. The extensive armour in Gerrothorax probably constituted a calcium reservoir, indicated by cyclical resorption events preserved in the external cortex and interpreted as a physiological response to periodic changes in salinity of the aquatic environment. In contrast, the unique osteoderm structure of dissorophids provides maximum stability and minimum bone mass, and is coherent with the interpretation that the osteoderms served to strengthen the vertebral column during terrestrial locomotion.     

小熊猫胃的解剖和组织结构研究

小熊猫的胃属单室腺型胃,它以角切迹为界,可分为胃底部和幽门部两部分。胃壁由粘膜、粘膜下层、肌层和浆膜四层组成。四上皮为单层柱状上皮,具有分泌粘液的功能。胃腺有贲门腺、胃底腺、幽门腺三种,但贲门腺不发达。主细胞、壁细胞和粘液细胞的数量与分布呈现规律性变化。肌层发达,特别是内环行肌发达。并与大熊猫胃的结构作了比较。     

鸟类哈氏腺的研究进展

本文对鸟类哈氏腺的解剖学、组织学及生理功能的研究进展进行了综述,对其未来的研究方向进行了展望,以期为此领域的研究提供参考。大多数鸟类哈氏腺的形态大体上无实质性差异,最常见的与家鸡相似：形状不规则,腺体被一层薄的结缔组织包膜隔成不同的小叶。根据小叶结构和排列在腺泡及小管的上皮细胞种类,鸟类哈氏腺可分为三类,即复管泡状腺,复管状腺和混合型腺,复管泡状腺中家鸡为代表,复管状腺中家鸭为代表,混合型中秃鼻乌鸦（Corvusfrugilegus）为代表。腺体结构的类型可能与鸟类习性和行为有关。鸟类哈氏腺除最基本的润滑角膜和瞬膜功能外,还是B细胞活化和终末分化以及浆细胞增殖的场所,作为外周免疫器官,与脾脏、法氏囊和盲肠集合淋巴样组织一起构成决定鸟类全身和局部免疫反应的器官系统。