Development of face-1

The chordamesoderm induces the formation of	Neural crest. From the ectoderm, due to the interactive inductive stimuli between cells separated by a distance for a short time, neural crest cells are formed.
The set of cells that arise from the ectoderm along the lateral margins of neural plate are the	Neural crest. These cells undergo migration at the time of neural tube closure.
Of all the hard tissues of oral cavity the one that is non-neural crest in origin is the	Enamel. Enamel is derived from inner enamel epithelium that arises from oral ectodermal lining.
Migrating neural crest cells in the upper facial region forms	The entire mesenchyme. In the lower facial arch region the migrating neural crest cells surround the pharyngeal arch to form the bars, whereas in the upper facial region they ramify and form the entire mesenchyme.
Most of the sensory neurons of cranial sensory ganglia originate from	Neural crest tissues. Only in the trunk they originate from neural crest cells. In head most of them are derived from surface ectoderm.
The neural crest cells aggregate around the neural tube where the	Sensory ganglia of 5th, 7th, 9th and 10th Cranial nerve form
The condensed masses of cells of mesodermal origin adjacent to neural tube are	Somites. They give rise to muscle cells
The first formed supporting cells of blood vessels from the ectomesenchyme are the	Pericytes
The growth and fusion of upper facial prominences produces the	Primary and secondary palate
Inductive influences originating from forebrain initiate the formation of	Nasal placodes. Before the neural crest cell migration, the surface ectoderm lies in apposition to portions o developing forebrain. After this induction, the mesenchymal tissues separate the ectoderm from developing forebrain.
The “Placodes” are thickenings of	Ectoderm. These ectodermal thickenings give rise to various vital sense organs such as the lens and olfactory epithelium.
The nasal placodes will give rise to	Sensory epithelium of olfaction
The medial and lateral nasal prominences contact each other	Below nasal pit. With this contact the epithelium breaks down so that the mesenchyme becomes continuous.
In human embryo the medial and lateral nasal prominences fuses during	Fifth week IUL
Initial nasal passage is formed near the fusion of medial and lateral nasal placodes by	Accumulation of fluid between epithelial cells. This fluid accumulation causes the epithelial cells to separate creating a passage at about 5th week of intrauterine life and connects the olfactory pit with the roof of primitive oral cavity.
The medial and lateral nasal prominences fuse and give rise to	Primary palate
The roof of the anterior part of primitive oral cavity is formed by	Primary palate
The primary palate gives rise to the	Part of upper lip, anterior maxilla and upper incisors
The secondary palate arises from the	Medial edge of maxillary prominences
The palatal shelves growth direction is	Downward beside tongue. This growth occurs beside the tongue when it probably fills partially the nasal cavity.
In humans, the palatal shelves fuse at about	Ninth week intrauterine life
Alteration in the epithelium at the medial edge of the palatine shelves before its fusion causes	Cessation of cell division; Raise in cAMP; Increased surface adhesive glycoprotein. The cessation of cell division is mediated by a various biochemical pathways. In addition apoptosis is also noted.
During secondary palate formation the palatal shelves, in anterior region, are brought to horizontal position by	Rotational movement
During secondary palate formation the palatal shelves, in posterior region, are brought to horizontal position by	Remodeling and rotational movement. Shelves are incapable of elevation till tongue is withdrawn. This occurs with the help of contractile elements. Remodeling brings about change in shape.
The pituitary gland develops from	Ventral forebrain and oral ectoderm. As a result of inductive interaction between the ventral forebrain and oral ectoderm and is hence derived from both the tissues.
In humans, the total number of visceral arches is	Six
Mesodermal core of each visceral arch is primarily concerned with the formation of	Vascular endothelial cells
In humans, the rudimentary pharyngeal arch is	Fifth
The proximal part of the first visceral arch forms	Maxillary prominence
The mesoderm of mandibular and hyoid arch gives rise to	5th and 7th Nerve musculature
The mesoderm of 3rd and 4th arch gives rise to	9th and 10th Nerve musculature
The crest mesenchymal cells of visceral arches give rise to the	Skeletal components; Connective tissues; Tongue
In humans, the tongue formation initiates in the	Ventral floor of pharynx
During development, the covering of tongue is	Anterior two third ectoderm and posterior one third endoderm
Mesenchymal component of anterior two thirds of human tongue are derived from	Third arch mesenchyme
The lateral extension from the inner groove between first and second arch gives to	Eustachian tube
The pinna is formed from	Both first and second arch
The embroyonic period of human lasts till	Eighth week intrauterine life
The most common defect of embryonic facial development is the	Cleft of primary and or secondary palate
Excess doses of vitamin A given to mother during pregnancy causes defects similar to	Treacher-Collin syndrome
The result of persistence of tuberculum impar after tongue formation is suggested to cause	Median rhomboid glossitis. This is an earlier hypothesis which is disagreed now and infection with candidal organism is the cause suggested now. Improper or incomplete union of the lateral lingual processes produces scrotal tongue and partial union produces the bifid or cleft tongue. Agenesis will be produced by the non formation of the lingual processes.