During intramembranous ossification, the developing bone grows outward from the ossification center in small struts called _

During intramembranous ossification, the developing bone grows outward from the ossification center in small struts called spicules.

Explanation:

The intramembrane ossification is the one that preferentially produces flat bones and, as the name implies, takes place within a connective tissue membrane. In this process, some of the mesenchymal cells that form the connective tissue membranes are transformed into osteoblasts constituting an ossification center around which bone is formed. Consequently, a certain amount of flat bones develop that are characterized by the presence of bone spicules. These spicules radiate from the primary ossification centers to the periphery. As growth continues during fetal and postnatal life, these bones increase in volume by apposition of layers on their outer surface and by osteoclastic resorption from the inside of each bone.

b. lithosphere, asthenosphere, mesosphere   is the answer most likely