Chapter 3, Problem 1CYU

Dining which prenatal period is the basic body plan established?

Summary Introduction

To review:

The prenatal period during which the establishment of basic body plan takes place.

Introduction:

The development of a fetus takes 38 weeks from the time of fertilization of an egg. This period is known as a prenatal period that is divided into embryonic, fetal, and germinal period. The germinal period spans from the conception to 2 weeks after the fertilization. Third to eighth week is marked by an embryonic period.

Explanation of Solution

  

The body plan is established during an embryonic period of prenatal period. The basic body plan is a tube within a tube structure. The outer tube forms the outer body wall and the inner tubes forms the respiratory and digestive tract. These tubes are separated by a serous cavity. The structures in the basic body plan are skin, outer body wall, body cavity, inner tube, kidney, gonads, and limbs. The skin consists of two layers: outer epidermis and inner dermis. The outer body wall includes the trunk muscles.

The inner body tube in the abdominal and thoracic cavity contains the digestive and respiratory tract, respectively. The pericardial and pleural cavity separates the heart and lungs, in the respiratory tract, from the outer body wall. The peritoneal cavity in the abdomen separates the digestive tract from the outer body wall. These cavities are lined by visceral and parietal serosa. The muscle, bone, and skin constitute the limbs.