Lecture 14 (Exam 2) Flashcards
Skeletal tissue is _________ in origin.
Mesenchymal
Mesodermal sclerotomes (of somites) give rise to…
Vertebral column
Ribs
Sternum
The lateral plate mesoderm gives rise to…
Limb bones
Girdles
The head mesoderm gives rise to…
Calvaria
Base of skull
The neural crest gives rise to the _______ bones.
Facial
The ______ skeleton is a continuous interaction between apical ectodermal ridge and limb bud mesoderm.
Limb
The _______ _______ is an inductive interaction between sclerotome and notochord or neural tube.
Vertebral column
The _______ is an interaction between pre skeletal neural crest cells and information along migratory paths.
Head
The head has interactions between areas of the _______ and overlying mesenchyme.
Brain
For bone/cartilage differentiation, sometimes mesenchyme is induced to enter the common pathway. Production of _______ promote mesenchymal cell condensation. After they are condensed, ______ stimulates synthesis of _______ and _______. This makes the aggregated state of mesenchymal cells stabilized.
N-cadherins
TGF-B
Fibronectin
N-CAM
For bone/cartilage differentiation, after the common pathway, another pathway to be taken is the membranous bone pathway. This requires transcription factors _____ and _____. Mesenchymal cells are differentiated into ________.
Runx-2
Osx
Osteoblasts
For bone/cartilage differentiation, after the common pathway, another pathway to be taken is the permanent cartilage pathway. Mesenchymal condensation forms chondroblasts. ______ causes chondroblasts to secrete ________ and _______ matrix. ______ is continually expressed in permanent cartilage.
Sox-9
Collagen II
Cartilage
Sox-9
For bone/cartilage differentiation, after the common pathway, another pathway to be taken is the endochondral bone pathway. ______, ______, and ______ induce this cartilage to undergo hypertrophy. Hypertrophic cartilage cells secrete bone proteins and vascular endothelial growth factor.
Runx-2
ihh
BMP-6
In the endochondral bone pathway, invading blood vessels erode the hypertrophic cartilage and bring in _______ to replace cartilage with ______.
Osteoblasts
Bone
This part of a vertebra is derived from ventral and medial parts of paired sclerotomes.
Centrum
This part of a vertebra arise from dorsal regions of sclerotomes. These are related to spina bifida due to a failure of these to fully close.
Neural arches
The proximal development of costal processes and ribs depend on expression of myotomic myogenic factors, _____ and _____. Distal development depends on _____ signals from somatopleural mesoderm.
Myf-5
Myf-6
BMP
The fundamental regional characteristics of the vertebrae are specified by actions of discrete combinations of ______ genes.
Hox
______ _____ can cause shifts in cranial or caudal levels in the overall segmental organization of the vertebrae if it is applied at specific developmental periods.
Retinoic acid
For example, if administered early, retinoic acid results in a cranial shift (the last cervical vertebra is transformed into the first thoracic vertebra), and later administration causes a caudal shift (thoracic vertebrae extend into the levels of the first two lumbar vertebrae). Such shifts in level are called…
Homeotic transformations
When single Hox genes are knocked out (MAJOR/MINOR) morphological effects are noted.
Minor
When all members of a paralogous group are knocked out, a profound effect appears. For example, knockout of all ______ paralogues results in ribs forming on all the lumbar and sacral vertebrae. This suggests that ______ represses the influence of the more anterior Hox genes.
Hox10
______ suppresses the influence of Hox10 and allows the sacrum to form. Without it, this could not occur.
Hox11
A mutant of a single Hox gene is likely to produce a (MAJOR/MINOR) anatomical defect.
Minor
This is derived from lateral plate mesoderm. It arises as a pair of cartilaginous bands that fuse and secondarily subdivide into craniocaudal elements.
Sternum
This arises from the neural crest. It follows the intramembranous pathway and is one of the first bones to become ossified.
Clavicle
The developing embryonic skull is composed of…
Neurocranium
Viscerocranium
Occipital sclerotomes
This is the part of the skull that surrounds the brain. It has a cartilaginous portion and a membranous portion.
Neurocranium
The neurocranium base is formed from the chondrocranium (_________ part). It’s the origin of occipital, sphenoid, ethmoid, and parts of temporals.
Cartilaginous
The neurocranium (CARTILAGINOUS/MEMBRANOUS) part is the origin of part of occipital, parietals, frontals, and part of temporals.
Membranous
This surrounds the oral cavity and pharynx, and refers to pharyngeal arches. It also has a cartilaginous and membranous portion.
Viscerocranium
The (MEMBRANOUS/CARTILAGINOUS) portion of the viscerocranium forms pharyngeal arch I (Meckel’s cartilage, malleus, incus) and pharyngeal arch II (Reichert’s cartilage, stapes, styloid).
Cartilaginous
The (MEMBRANOUS/CARTILAGINOUS) portion of the viscerocranium forms part of temporal, zygomatic, maxillary, nasal, lacrimal, palatine, vomer, pterygoid plates, mandible, and tympanic ring.
Membranous
The viscerocranium is mostly comprised of the branchial (pharyngeal) arches. The mesenchyme that forms the viscerocranium is mostly from neural crest. There are _____ pairs of pharyngeal arches.
Six
Each pharyngeal arch consists of four components, which are…
Skeletal element
Muscles
A branch of a specific cranial nerve
Artery
Intersection of more than two bones form…
Fontanelles
In the fusion of sutures, the presence of _____ down regulates ______, which lets ______ close sutures.
FGF-2
Noggin
BMP
In the fusion of sutures, the absence of _____ leads to more ______ and repressed _____, leaving sutures open.
FGF-2
Noggin
BMP
