Mateusz Hermyt

Bio: Mateusz Hermyt is an academic researcher from University of Silesia in Katowice. The author has contributed to research in topics: Egg tooth & Enamel organ. The author has an hindex of 4, co-authored 7 publications receiving 65 citations.

Embryology of the VNO and associated structures in the grass snake Natrix natrix (Squamata: Natricinae): a 3D perspective

Abstract: Snakes are considered to be vomerolfaction specialists. They are members of one of the most diverse groups of vertebrates, Squamata. The vomeronasal organ and the associated structures (such as the lacrimal duct, choanal groove, lamina transversalis anterior and cupola Jacobsoni) of adult lizards and snakes have received much anatomical, histological, physiological and behavioural attention. However, only limited embryological investigation into these structures, constrained to some anatomical or cellular studies and brief surveys, has been carried out thus far. The purpose of this study was, first, to examine the embryonic development of the vomeronasal organ and the associated structures in the grass snake (Natrix natrix), using three-dimensional reconstructions based on histological studies, and, second, to compare the obtained results with those presented in known publications on other snakes and lizards. Five major developmental processes were taken into consideration in this study: separation of the vomeronasal organ from the nasal cavity and its specialization, development of the mushroom body, formation of the lacrimal duct, development of the cupola Jacobsoni and its relation to the vomeronasal nerve, and specialization of the sensory epithelium. Our visualizations showed the VNO in relation to the nasal cavity, choanal groove, lacrimal duct and cupola Jacobsoni at different embryonic stages. We confirmed that the choanal groove disappears gradually, which indicates that this structure is absent in adult grass snakes. On our histological sections, we observed a gradual growth in the height of the columns of the vomeronasal sensory epithelium and widening of the spaces between them. The main ophidian taxa (Scolecophidia, Henophidia and Caenophidia), just like other squamate clades, seem to be evolutionarily conservative at some levels with respect to the VNO and associated structures morphology. Thus, it was possible to homologize certain embryonic levels of the anatomical and histological complexity, observed in the grass snake, with adult conditions of certain groups of Squamata. This may reflect evolutionary shift in Squamata from visually oriented predators to vomerolfaction specialists. Our descriptions offer material useful for future comparative studies of Squamata, both at their anatomical and histological levels.

Squamate egg tooth development revisited using three-dimensional reconstructions of brown anole (Anolis sagrei, Squamata, Dactyloidae) dentition.

Abstract: The egg tooth is a hatching adaptation, characteristic of all squamates. In brown anole embryos, the first tooth that starts differentiating is the egg tooth. It develops from a single tooth germ and, similar to the regular dentition of all the other vertebrates, the differentiating egg tooth of the brown anole passes through classic morphological and developmental stages named according to the shape of the dental epithelium: epithelial thickening, dental lamina, tooth bud, cap and bell stages. The differentiating egg tooth consists of three parts: the enamel organ, hard tissues and dental pulp. Shortly before hatching, the egg tooth connects with the premaxilla. Attachment tissue of the egg tooth does not undergo mineralization, which makes it different from the other teeth of most squamates. After hatching, odontoclasts are involved in resorption of the egg tooth's remains. This study shows that the brown anole egg tooth does not completely conform to previous reports describing iguanomorph egg teeth and reveals a need to investigate its development in the context of squamate phylogeny.

Do all geckos hatch in the same way? Histological and 3D studies of egg tooth morphogenesis in the geckos Eublepharis macularius Blyth 1854 and Lepidodactylus lugubris Duméril & Bibron 1836.

Abstract: The egg tooth of squamates evolved to facilitate hatching from mineralized eggshells Squamate reptiles can assist their hatching with a single unpaired egg tooth (unidentates) or double egg teeth (geckos and dibamids) Egg tooth ontogeny in two gekkotan species, the leopard gecko Eublepharis macularius and the mourning gecko Lepidodactylus lugubris, was compared using microtomography, scanning electron microscopy, and light microscopy Investigated species are characterized by different hardnesses of their eggshells Leopard geckos eggs have a relatively soft and flexible parchment (leathery) shell, while eggshells of mourning geckos are hard and rigid Embryos of both species, like other Gekkota, have double egg teeth, but the morphology of these structures differs between the investigated species These differences in shape, localization, and spatial orientation were present from the earliest stages of embryonic development In mourning gecko, anlagen of differentiating egg teeth change their position on the palate during embryonic development Initially they are separated by condensed mesenchyme, but later in development, their enamel organs are connected In leopard geckos, the localization of egg tooth germs does not change, but their spatial orientation does Egg teeth of this species shift from inward to outward orientation This is likely related to differences in structure and mechanical properties of eggshells in the studied species In investigated species, two hatching mechanisms are possible during emergence of young individuals We speculate that mourning geckos break the eggshell through puncturing action with egg teeth, similar to the pipping phase of chick and turtles embryos Egg teeth of leopard geckos cut egg membranes similarly to most squamates Our results also revealed differences in egg tooth implantation between Gekkota and Unidentata: gekkotan egg teeth are subthecodont (in shallow sockets), while those in unidentates are acrodont (attached to the top of the alveolar ridge) © 2020 Wiley Periodicals LLC

Manson's Tropical Diseases

Abstract: The first edition of this reference work was published in 1898, and the last update was published in 1972. This current edition is written by six major contributors and contains either rewritten or new chapters, including one 29-page chapter entitled "Ophthalmology in the Tropics" by F. C. Rodger, MD. Not only is this material valuable to physicians in endemic areas, but it is also important for travelers to the tropics who may return home with these diseases. Most of the chapters discuss the following aspects of tropical disease: cause, transmission, immunology, epidemiology, geographical distribution, pathologic condition, clinical findings, and diagnosis (including laboratory findings, treatment, and prevention). Beside chapters on infections, there are chapters on disorders due to heat, nutritional diseases, and venoms and poisons, and appendices on protozoology, helminthology, entomology, and clinical pathologic conditions. Excellent illustrations of end-stage pathologic conditions are disconcerting. Ophthalmologists would be most interested in the discussion

When the Pancreas

Abstract: 1757 Identification of Ocular Sebaceous Neoplasia with Evaluation for Mismatch Repair Proteins L Schoenfield, J Anthony, R Djohan, I Lalak, M Levine, P Ng, J Perry, A Singh, T Plesec. Cleveland Clinic, Cleveland, OH. Background: Recognizing sebaceous carcinoma is important because of its risk for metastasis and tumor death. Histopathology alone is often difficult because fresh tissue for oil red-O stain is not always available. Several immunohistochemical stains (IHC) have been evaluated but often the diagnosis is elusive. Furthermore, the diagnosis of a sebaceous adenoma or carcinoma raises the possibility of Lynch syndrome, a cancer predisposition syndrome. Mismatch repair protein(MMR) abnormalities are a feature of Lynch syndrome, and they can be detected with IHC for the MLH1, MSH2, PMS2, and MSH6 proteins. Design: 14 sebaceous carcinomas and 3 adenomas from the eyelid (17 specimens) from 14 patients were evaluated for oil red-O when possible as well as IHC for AR, EMA, BER-EP4, CAM5.2 for diagnosis. MMR for MLH1, MSH2, PMS2, and MSH6 by IHC were evaluated as a possible screening panel for Lynch syndrome. Two patients already had other tissue tested by PCR for microsatellite instability (MSI) for Lynch syndrome. Results: Oil red-O was done on 6 of 17 specimens and positive in 5 of the 6 (83%). AR was positive in 2 of 3 adenomas (67%) and 5 of 14 carcinomas (36%). EMA was positive in 2 of 3 adenomas (67%) and 11 of 14 carcinomas (79%). BER-EP4 was negative in all 3 adenomas and positive in 7 of 14 carcinomas (50%). CAM5.2 was positive in 1 of 3 adenomas (33%) and 8 of 14 carcinomas (57%). All 17 specimens(100%) showed positive nuclear staining for MLH1 and PMS2, indicative of normal protein expression. In 14 of 17 specimens from 12 patients, MSH2 and MSH6 were also normal. 3 specimens from 2 patients that had rare positive cells for MSH2 and MSH6. Both patients had previous colonic tumors tested for MSI and were found to be MSI-H, indicative of possible Lynch syndrome. Conclusions: Diagnosing sebaceous carcinoma is important prognostically but sometimes challenging with routine histopathology. In our experience androgen receptor (AR) was found to be confirmatory in only 36% of cases and not dependent on the size of the tumor available. The other IHC stains were of marginal benefit and not specific. While none of the cases showed complete loss of expression of a MMR protein, there were 2 patients in with only rare positive cells who had known MSI-H tumors in the colon, suggestive of Lynch syndrome. Additional studies of these eyelid tumors may elucidate the possible role of using them for screening for Lynch syndrome.

Higher resting metabolic rate in long-lived breeding Ansell’s mole-rats ( Fukomys anselli )

Abstract: Reproduction is an energetically expensive process that supposedly impairs somatic integrity in the long term, because resources are limited and have to be allocated between reproduction and somatic maintenance, as predicted by the life history trade-off model The consequence of reduced investment in somatic maintenance is a gradual deterioration of function, ie senescence However, this classical trade-off model gets challenged by an increasing number of contradicting studies Here we report about an animal model, which adds more complexity to the ongoing debate Ansell’s mole-rats are long-lived social subterranean rodents with only the founder pair reproducing, while most of their offspring remain in the parental burrow system and do not breed Despite of a clear reproductive trade-off, breeders live up to twice as long as non-breeders, a unique feature amongst mammals We investigated mass-specific resting metabolic rates (msRMR) of breeders and non-breeders to gain information about the physiological basis underlying the reproduction-associated longevity in Ansell’s mole-rats We assessed the thermoneutral zone (TNZ) for breeders and non-breeders separately by means of indirect calorimetry We applied generalized linear mixed-effects models for repeated measurements using the msRMR in the respective TNZs TNZ differed between reproductive and non-reproductive Ansell’s mole-rats Contrary to classical aging models, the shorter-lived non-breeders had significantly lower msRMR within the thermoneutral zone compared to breeders This is the first study reporting a positive correlation between msRMR and lifespan based on reproductive status Our finding contradicts common aging theories, but supports recently introduced models which do not necessarily link reproductive trade-offs to lifespan reduction