NEET PG DENTAL EXAM

EMBRYOLOGY

FERTILISATION EARLY DEVELOPMENT OF EMBRYO AND IMPLANTATION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
What is the first organ that begins to function in the developing embryo?
A
the lungs
B
the limbs
C
the brain
D
the heart
Explanation: 

Detailed explanation-1: -The first organ system to develop during organogenesis is the cardiovascular system. The heart has established its four chambers by four weeks of development, whereas week six involves cardiac outflow separation and descent of the heart (and lungs) into the thorax.

Detailed explanation-2: -The heart forms from an embryonic tissue called mesoderm around 18 to 19 days after fertilization. Mesoderm is one of the three primary germ layers that differentiates early in development that collectively gives rise to all subsequent tissues and organs.

Detailed explanation-3: -Organogenesis. In addition to neurulation, gastrulation is followed by organogenesis, when organs develop within the newly formed germ layers. Most organs start to develop during the third to eighth weeks following fertilization. They will continue to develop and grow during the following fetal period.

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