'''คัพภวิทยา''' หรือ '''วิทยาเอ็มบริโอ''' ([[ภาษาอังกฤษ|อังกฤษ]]: Embryology) เป็นการศึกษาการเจริญของ[[เอ็มบริโอ]] เอ็มบริโอคือขั้นหนึ่งของการเจริญของ[[สิ่งมีชีวิต]]ก่อนคลอดหรือออกจากไข่ หรือในพืชคือในระยะก่อนการงอก (germination)
[[ภาพ:Embryo, 8 cells.jpg|thumb|240px|right|ตัวอ่อนระยะมอรูลา (Morula) , ระยะ 8 เซลล์]]
Embryology refers to the development of the fertilized egg cell ([[zygote]]) and its differentiation into tissues and organs. After cleavage, the dividing cells, or [[morula]], becomes a hollow ball, or [[blastula]], which develops a hole or pore at one end.
[[ภาพ:Blastulation.png|thumb|240px|right|'''1''' - morula, '''2''' - blastula]]
In animals, the [[blastula]] develops in one of two ways that divides the whole animal kingdom into two halves. If in the [[blastula]] the first pore ([[blastopore]]) becomes the mouth of the animal, it is a [[protostome]]; if the first pore becomes the anus then it is a [[deuterostome]]. The [[protostomes]] include most [[invertebrate]] animals, such as insects, worms and molluscs, while the [[deuterostomes]] includes more advanced animals including the [[vertebrates]]. In due course, the [[blastula]] changes into a more differentiated structure called the [[gastrula]].
[[ภาพ:Gastrulation.png|thumb|240px|'''1''' - blastula, '''2''' - gastrula
with blastopore; ''' orange''' - ectoderm, ''' red''' - endoderm.]]
The [[gastrula]] with its [[blastopore]] soon develops three distinct layers of cells (the [[germ layers]]) from which all the bodily organs and tissues then develop:
* The innermost layer, or [[endoderm]], gives rise to the digestive organs, lungs and bladder.
* The middle layer, or [[mesoderm]], gives rise to the muscles, skeleton and blood system.
* The outer layer of cells, or [[ectoderm]], gives rise to the nervous system and skin.
In humans, the term embryo refers to the ball of dividing cells from the moment the [[zygote]] implants itself in the [[uterus]] wall until the end of the eighth week after conception. Beyond the eighth week, the developing human is then called a fetus. Embryos in many species often appear similar to one another in early developmental stages. The reason for this similarity is because species have adapted into the environment of pregnancy. These similarities among species are called [[analogous structures]], which are structures that have the same or similar function and mechanism, but evolved separately.
[[ภาพ:6 weeks pregnant.png|right|thumb|Human embryo at six weeks gestational age]]
== History ==
With a very long history, embryology is a subject that has engaged the minds of some of the most brilliant and original biological thinkers and experimentalists.