The primary female reproductive organs, the ovaries, produce mature ova and the female sex hormones:

Long, threadlike structures made of protein and nucleic acid containing hereditary materials are known as :

The  prenatal development of  the organs of the fetus assume their specialized functions during the :

The principal male sex hormones are:

The newly fertilized ovum is called a :

The principle that describes development as starting with the head and brain areas and moving downward is called:

The optimal time for fertilization  to occur within the menstrual cycle is:

An absolutely essential growth process that begins within a few hours of fertilization and is a division of cells into identical cells  is called:

As a result of cleavage, the zygote becomes transformed into a hollow ball of cells called the:

Sex cells (sperm and ova) are called: