Meis2 controls skeletal formation in the hyoid region.

A vertebrate skull is composed of many skeletal elements which display enormous diversity of shapes. Cranial bone formation embodies a multitude of processes, i.e.

The Mandibular and Hyoid Arches-From Molecular Patterning to Shaping Bone and Cartilage.

The mandibular and hyoid arches collectively make up the facial skeleton, also known as the viscerocranium. Although all three germ layers come together to assemble the pharyngeal arches, the majority of tissue within viscerocranial skeletal components differentiates from the neural crest. Since nearly one third of all birth defects in humans affect the craniofacial region, it is important to understand how signalling pathways and transcription factors govern the embryogenesis and skeletogenesis of the viscerocranium.

Neural crest cells require Meis2 for patterning the mandibular arch via the Sonic hedgehog pathway.

Cranial neural crest cells (cNCCs) originate in the anterior neural tube and populate pharyngeal arches in which they contribute to formation of bone and cartilage. This cell population also provides molecular signals for the development of tissues of non-neural crest origin, such as the tongue muscles, teeth enamel or gland epithelium. Here we show that the transcription factor Meis2 is expressed in the oral region of the first pharyngeal arch (PA1) and later in the tongue primordium.

Vermian fossa or median occipital fossa revisited: Prevalence and clinical anatomy.

Introduction: The vermian fossa (VF) is a small midline depression at the inferior end of the internal occipital crest (IOC) near the foramen magnum. This study aims to accurately define the usual arrangement ("the norm") of the inferior end of the internal occipital crest, to determine the prevalence and dimensions of the VF in Central European population, and to state a possible correlation of the VF with anatomical variations and developmental abnormalities.

Materials And Methods: We analyzed the prevalence of the VF in 1042 dry skulls.