True during development the skeleton of a fetus is made of cartilage which is converted to bone before birth

Early in gestation, a fetus has a cartilaginous skeleton that becomes bone in ... At birth, a newborn baby has over 300 bones, while on average an adult human has 206 bones ... It is composed of fibers and granular cells in a matrix. ... The hypertrophic chondrocytes (before apoptosis) secrete vascular endothelial cell growth ...

Explanation

n:When does the fetal cartilage turn to bone?

Key milestones in fetal bone development

Weeks pregnantMilestone

7 weeksBone outlines for entire skeleton established; cartilage is forming

8 weeksSomites disappear; joints start forming

10 weeksBone tissue forms and starts hardening (ossification)

16 weeksYour baby can move his limbs

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.

the tricuspid valve is present between right atrium and right ventricle