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doi: 10.1002/jmor.1051820302pmid: 30049067
The sequence of appearance of the 17 different skull bones in the oriental fire‐bellied toad, Bombina orientalis, is described. Data are based primarily on samples of ten or 11 laboratory‐reared specimens of each of 11 Gosner developmental stages (36–46) representing middle through late metamorphosis. Ossification commences as early as stage 37 (hind limb with all five toes distinct), but the full complement of adult bones is not attained until stage 46 (metamorphosis complete). Number of bones present at intermediate stages is poorly correlated with external morphology. As many as four Gosner developmental stages elapse before a given bone is present in all specimens following the stage at which it may first appear. The modal ossification sequence is frontoparietal, exoccipital, parasphenoid, septomaxilla, premaxilla, vomer, nasal, maxilla, angulosplenial, dentary, squamosal, quadratojugal, pterygoid, prootic, interfrontal, sphenethmoid, and mentomeckelian. Most specimens are consistent with this sequence, despite the poor correlation between cranial ossification and external development as assayed by Gosner stage.
Garrett, Margaret A.; Bradley, Timothy J.
doi: 10.1002/jmor.1051820303pmid: 6151601
The ultrastructure of the Malpighian tubules, ileum, rectum, anal canal, and anal papillae of larvae of the mosquito Culiseta inornata was examined. The Malpighian tubules, rectum, and anal papillae have many of the ultrastructural features characteristic of ion transport tissues, i.e., elaboration of the basal and apical membranes and a close association of these membranes with mitochondria. The Malpighian tubules possess two cell types, primary and stellate. The larval rectum of C. inornata is composed of a single segment containing a homogenous population of cells. In this respect, the larval rectum of C. inornata is distinct from that of saline‐water species of Aedes. The cells in the larval rectum of C. inornata, however, closely resemble those of one cell type, the anterior rectal cells, of the saline‐water mosquito Aedes campestris with regard to cell and nuclear size, the percentage of the cell occupied by apical folds, and mitochondrial density and distribution. No similarities can be found between the rectum of C. inornata and the posterior segment of the saline‐water Aedes, which functions as a salt gland. On this basis, we have postulated that the rectum of C. inornata does not function as a site of hyperosmotic fluid secretion. The ultrastructure of the anal papillae of C. inornata is consistent with a role in ion transport. The significance of these findings to comparative aspects of osmoregulatory strategies in mosquito larvae is discussed.
doi: 10.1002/jmor.1051820304pmid: 30029569
Among cockroaches in the subfamily of Oxyhaloinae, the adult males produce two essential and successively active chemical signals: the sex pheromone attracting females from a distance secreted by the sternal glands, and the aphrodisiac required for mating which is secreted by the tergal glands. The adult males of the seven species studied, Nauphoeta cinerea, Henschoutedenia flexivitta, Leucophaea maderae, Jagrehnia madecassa, Gromphadorhina portentosa, G. laevigata, and G. chopardi, possess well‐developed sternal and tergal glands whose number varies according to the species and methods of mating (three to six sternal glands and four to seven tergal glands). These glands are basically composed of type three glandular units (glandular cell + duct cell) and type 2 cells (modified oenocytes) which exhibit no significant external cuticular modification except for tergite 2 of L. maderae. The extreme variance in development of these glands can be linked to sexual behavior. The hypothesis put forward here is that of a regressive evolution of the tergal glands, related to a modification of the role played by the aphrodisiacs which they secrete.
Martin, T. J.; Blaber, S. J. M.
doi: 10.1002/jmor.1051820305pmid: 30025439
The gross morphology and histology of the alimentary tracts of three species of glassy perchlet; Ambassis productus, A. natalensis, and A. gymnocephalus from estuaries on the southeast coast of Africa were investigated. The anatomy of the digestive tracts in all three species was found to be similar. Well‐developed dentition and pharyngeal teeth together with a distensible stomach and a low relative gut length (RGL) suggest a predatory and carnivorous habit for all three species.
doi: 10.1002/jmor.1051820306pmid: 30016851
The adrenergic innervation of structures in the gills of brown and rainbow trout was studied with catecholamine fluorescence histochemistry.
doi: 10.1002/jmor.1051820307pmid: 6240541
Cross sections through the middle segment of the anuran rectus abdominis muscle were analyzed morphometrically at nine stage of development, from early larval life through full maturity. The numbers, sizes, and relative distributions of twitch and slow muscle fibers, newly differentiated fibers, degenerating fibers, and satellite cells were determined at each stage. The data indicate that the muscle increases slowly in size and fiber content during early larval life. New fibers appear to form primarily along the medial margin of the muscle. During mid‐larval stages, when thyroid hormone levels are rising, new fibers form throughout the medial portion of the muscle. At a slightly later stage, fibers in the lateral region of the muscle begin to degenerate. Structurally normal presynaptic elements are present on both degenerating fibers and the empty basal laminae of fibers that had been removed by phagocytes. Both fiber formation and fiber loss slow during midmetamorphic climax, at the time when thyroid hormone levels reach a peak in anurans and begin to decline. Degenerating fibers appear within the body of the muscle at the end of metamorphosis. By the end of the second postmetamorphic month, neither degenerating nor newly differentiated fibers are present. The muscle continues to grow through adult life primarily by fiber hypertrophy.
doi: 10.1002/jmor.1051820308pmid: 30029565
The presence of both book lungs and a tracheal system in many spiders raises the question of the functional significance of this double respiratory system. The present physiological and morphometric study of the house spider (Tegenaria spp.) reveals that the diffusing capacity (Dto2) of the lungs alone suffices during rest and following exercise to meet measured rates of oxygen consumption (\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm.} $\end{document}o2) at driving pressures (ΔPto2) similar to those calculated for vertebrate lungs. During moulting ΔPto2 may rise to more than double the vertebrate values, implying the possible insufficiency of book lungs during this critical life phase. Resting \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} $\end{document}o2 is greatest (92 mm3/h · g) during the early morning and lowest (66 mm3/h · g) near midday: during moulting \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} $\end{document}o2 rises to 278.7 mm3/h · g. In spiders recovering from exercise \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} $\end{document}o2 is consistently greater than during rest: neither value is significantly reduced by blockage of the tracheal stigmas. Regression calculations of morphometric values for a hypothetical 100‐mg Tegenaria yield a total lung volume of 0.578 mm3, a pulmonary surface area of 69.8 mm2, and a surface‐to‐volume ratio of 120.89 mm2/mm3. In spite of the similar thickness of the chitinous and hypodermal components of the air‐hemolymph barrier (each ca. 0.2 μm in nonmoulting animals), the low permeability of chitin for oxygen makes this layer the greater barrier to diffusion. For a 100‐mg specimen Dto2 is 3.5 mm3/h · torr: similar to that of a turtle (Pseudemys) on a gram‐body weight basis.
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