**Question:** Secondary ossification centre appears before bih at

A. Epiphysis
B. Diaphysis
C. Metaphysis
D. Endochondral ossification

**Core Concept:** The process of endochondral ossification involves the formation of bone from cartilage, and occurs in two stages: primary and secondary ossification. Primary ossification occurs in the embryonic stage, where cartilage is replaced by bone. Secondary ossification, which is the focus of this question, occurs during later stages of development.

**Why the Correct Answer is Right:** The correct answer is option C, "Metaphyseal plate." In the process of secondary ossification, the growth plate (also known as the epiphyseal plate or growth plate) is formed at the junction of the diaphysis (option B) and the epiphysis (option A). The growth plate is the site of secondary ossification, where the cartilage is replaced by bone.

**Why Each Wrong Option is Incorrect:**

Option A, Epiphysis, refers to the bone surface that articulates with another bone. Epiphysis does not represent the site of secondary ossification.

Option B, Diaphysis, refers to the middle part of a long bone. The diaphysis is not the site of secondary ossification.

Option D, Endochondral ossification, is a process of bone formation from cartilage, but it is not the correct answer because it describes the process, not the site of secondary ossification.

**Clinical Pearl:** The process of secondary ossification is essential for understanding bone growth and development. This concept is particularly relevant in pediatric medicine, orthopedics, and developmental biology courses. In clinical practice, it helps understand conditions like epiphyseal growth disorders, epiphyseal dysplasia, and premature closure of growth plates, which can lead to limb deformities and short stature.