Home About us Contact
|
Home About us Contact | ||
|
|
||
Cranial Muscles (cranial + muscle)
Selected AbstractsCranial Muscles of the Sulawesi Babirusa (Babyrousa celebensis)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2 2010A. F. L. M. Kneepkens Summary With 12 figures and 1 table The detailed muscular anatomy of the head of the Sulawesi Babirusa (Babyrousa celebensis) is described for the first time. The results show that the muscular anatomy of the Babyrousa is very similar to the pig genus Sus, despite long geological separation from it. Some differences were noted: the M. parietoauricularis was more clearly separated into two parts in the Babirusa than in the domestic pig; the rostral fibres of the M. levator anguli oculi reached the infraorbital sinus in the Babirusa but only as far as the medial corner of the eye in the domestic pig; the M. palatinus of the Babirusa is paired and did not reach the Os palatinum, unlike its description in the domestic pig and the Platysma pars zygomatica originates from the fascia of the neck in the Babirusa, whereas that of the domestic pig originates largely or entirely from the scapula. [source] Expression of zebrafish six1 during sensory organ development and myogenesisDEVELOPMENTAL DYNAMICS, Issue 4 2004Dmitri A. Bessarab Abstract Drosophila sine oculis homologous genes in vertebrates are homeobox-containing transcription factors functioning within the Pax-Six-Eya-Dach regulatory network during development. In this study, we describe the cloning and expression of a zebrafish homolog of sine oculis, six1. The reverse transcription-polymerase chain reaction demonstrated accumulation of six1 transcripts at mid-gastrula, and in situ hybridization showed their subsequent expression in the cranial placode and later in the olfactory, otic, and lateral line placodes, inner ear, and neuromasts. In addition, six1 is expressed in the pituitary, branchial arches, somites, pectoral fin, ventral abdomen muscle, and the cranial muscles of the eye and lower jaw. An increase of six1 expression was observed in the lateral line, muscles, and inner ear of the mind bomb mutant, illustrating a regulatory effect of the Notch pathway on expression of Six genes. Developmental Dynamics 230:781,786, 2004 © 2004 Wiley-Liss, Inc. [source] Patterns of spatial and temporal cranial muscle development in the African clawed frog, Xenopus laevis (Anura: Pipidae)JOURNAL OF MORPHOLOGY, Issue 9 2007Janine M. Ziermann Abstract The African Clawed Toad, Xenopus laevis, has been a major vertebrate model organism for developmental studies for half a century. Because most studies have focused on the early stages of development, this has had the effect that many aspects of organogenesis and later development remain relatively poorly known in this species. In particular, little is known about cranial muscle development even at the level of morphology and histological differentiation of muscle anlagen and muscle fibers. In this study, we document the morphogenesis and histological differentiation of cranial muscles in X. laevis. We provide a detailed account of the timing of development for each of the cranial muscles, and also describe a new muscle, the m. transversus anterior. The cranial musculature of X. laevis larvae generally develops in a rostrocaudal sequence. The first muscles to differentiate are the extrinsic eye muscles. Muscles of the mandibular and hyoid arches develop almost simultaneously, and are followed by the muscles of the branchial arches and the larynx, and by the mm. geniohyoideus and rectus cervicis. Despite the fact that differentiation starts at different stages in the different muscles, most are fully developed at Stage 14. These baseline data on the timing of muscle differentiation in the X. laevis can serve as a foundation for comparative studies of heterochronic changes in cranial muscle development in frogs and other lissamphibians. J. Morphol., 2007. © 2007 Wiley-Liss, Inc. [source] It is all in the head: morphological basis for differences in bite force among colour morphs of the Dalmatian wall lizardBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2009KATLEEN HUYGHE Males of the lizard Podarcis melisellensis occur in three distinct colours that differ in bite performance, with orange males biting harder than white or yellow ones. Differences in bite force among colour morphs are best explained by differences in head height, suggesting underlying variation in cranial shape and/or the size of the jaw adductors. To explore this issue further, we examined variation in cranial shape, using geometric morphometric techniques. Additionally, we quantified differences in jaw adductor muscle mass. No significant differences in size corrected head shape were found, although some shape trends could be detected between the colour morphs. Orange males have relatively larger jaw adductors than yellow males. Not only the mass of the external jaw adductors, but also that of the internal jaw adductors was greater for the orange morph. Data for other cranial muscles not related to biting suggest that this is not the consequence of an overall increase in robustness in orange individuals. These results suggest that differences in bite performance among morphs are caused specifically by an increase in the mass of the jaw adductor, which may be induced by differences in circulating hormone levels. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 13,22. [source] | ||||||||||