Preface

This course covers the basic topic of embryology, beginning with the female reproductive cycle, including the various factors that affect fertilization, and gametogenesis. Following that will be a variety of chapters that will cover the various development features that occur at different stages of the pregnancy.

Chapter one will include a discussion of the female reproductive cycle, including the hormones involved in ovulation. There needs to be a progressive and orderly release of certain hormones in order to have ovulation. Ovulation is necessary for fertilization and for the continuation of a pregnancy.

Chapter two will cover aspects of gametogenesis, including the way the egg cell develops in the female and the way the sperm cell develops in the male prior to fertilization. In actuality, there are similarities in the processes of meiosis in males and females, but there are significant differences as well.

The third chapter of the course will include a discussion of fertilization, the formation of the zygote, the way a zygote transforms into a blastula, and the process of gastrulation, in which a disc-shaped embryo becomes a three-dimensional structure.

In the fourth chapter of the course, we will have a discussion of how twins are made. There are two types of twins. Identical twins come from the same egg cell, while fraternal twins are the result of a woman ovulating two eggs at the same time and having both of those eggs fertilized by separate sperm.

The fifth chapter of the course will involve a discussion of the placenta and how it forms. There are tissues separate from the embryo itself that burrow into the uterine wall and differentiate to become the human placenta that carries forth throughout the pregnancy and nourishes the fetus.

In chapter six, there will be a thorough discussion of the second week of embryogenesis. It is during this time that embryo is disc-shaped and begins to develop from a few cells into a trilayered organism. Cells begin to differentiate into the ectoderm, the mesoderm, and the endoderm.

In the seventh chapter of the course, the way the embryo develops into a three-dimensional structure will be the focus of the discussion. During this time, some of the earliest organs begin to develop, with the circulatory system developing first.

In chapter eight, the fourth through eighth week of embryonic development will be the focus of discussion. This is a time when the embryo develops most of its organs and begins to take on the shape of a normal human being. By the end of this time, the embryo is called a fetus.

In chapter nine, the focus of the discussion will be on the basics of second trimester development. During this time, the fetus grows much longer, the organs develop further, and an amniocentesis can be done to evaluate the fetus for any chromosomal or genetic defects.

In chapter ten, the growth and development of the third trimester fetus will be discussed. During this time, the fetus picks up a lot of weight and its lungs develop so that it can live outside of the womb. Common complications of the third trimester will also be discussed.

In the eleventh and final chapter of the course, abnormalities of embryogenesis will be discussed, including nondisjunction, events that cause miscarriages, implantation problems, and the various problems faced by a child exposed to alcohol in utero.