Lec12 - Building Your Bones:Osteogenesis At 12 WEEKS: FETAL...

Info iconThis preview shows pages 1–15. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Building Your Bones:Osteogenesis At 12 WEEKS: FETAL SKELETON Pink Bones are Cartilagnous Red Bones are Ossified (Calcium) You Should Know that the Skull bones ( flat bones) were NEVER cartilage! They formed directly into bone ( de novo) How and When Do Our Bones Ossify? Osteogenesis and Ossifi cation are synonymous terms How and When Do Our Bones Ossify? 1. The hyaline cartilage of fetal skeleton changes to bone during the first 3 months of life. Also, certain bones form de novo. 2. Bones grow in length through early adulthood causing growth in height . Bones thicken throughout life. 3. All through life there is REMODELING and REPAIR Osteogenesis Two Types: 1. Intramembranous Ossification 2. Endochondral Ossification So.. When The Fetal Turns to Bone, It does it in Either of 2 Ways.. Depending On Which Bone We are Referring to Direct Ossification The embryonic connective tissue ossifies directly ( intramembranous ossification ) Intramembranous ossification takes place in the so- called dermal bones of the skull, clavicles and mandible . Intramembranous Ossification Condensation of mesenchyme into trabeculae Osteoblasts on trabeculae lay down osteoid tissue (uncalcified bone) Calcium phosphate is deposited in the matrix forming bony trabeculae of spongy bone Osteoclasts create marrow cavity Osteoblasts form compact bone at surface Surface mesenchyme produces periosteum Intramembranous Ossification 1 Produces flat bones of skull clavicle. Mandible. Intramembranous Ossification Fibrous sheets of primitive undifferentiated connective tissue appear in sites of future bone Connective tissue cells are arranged around blood vessels in the layers Cells differentiate into osteoblasts Intramembranous Ossification. Osteoblasts form spongy bone matrix around themselves in all directions- form trebeculae Osteoblasts become osteocytes when they are completely surrounded by bone matrix As matrix fills in, some spongy bone becomes compact bone Primitive connective tissue on the surface forms periosteum Cartilage to BONE ENDOCHRONDAL OSSIFICATION: THE STEPS OF: Endochondral Ossification. Perichondrium developes. Perichondrium is dense irregular connective tissue. Some cells of perichondrium differentiate into fibroblasts. Other cells of perichondrium remain mesenchyme Endochondral Ossification a.k.a. Intracartilaginous Bone Formation Mesenchyme cells proliferate, become tightly packed, form rough outline of bone Mesenchyme cells differentiate into chondroblasts- lay down hyaline cartilage matrix Hyaline cartilage model established. Endochondral Ossification a.k.a. Intracartilaginous Bone Formation Mesenchyme cells proliferate, become tightly packed, form rough outline of bone...
View Full Document

Page1 / 59

Lec12 - Building Your Bones:Osteogenesis At 12 WEEKS: FETAL...

This preview shows document pages 1 - 15. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online