austin biology

HUMAN EMBRYOLOG

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Embryology is the branch of biology that studies the prenatal development of gametes (sex cells), fertilization and development of embryos and fetuses.

It mainly focuses on the development that occurs in the parental period(gestational period)

DEFINITION

WHAT IS AN EMBRYO?An embryo is an early stage of development of a multicellular diploid eukaryotic organism.

In organisms that reproduce sexually, an embryo develops from a zygote, the single cell resulting from the fertilization of the female egg cell by the male sperm cell.The result of this process is an “embryo”.

DEVELOPMENT OF AN EMBRYO

PARENTAL PERIOD

Parental period is from fertilization through 8 weeks.It lasts 280 days 40 weeks 10 lunar months

Initial periodEmbryonic periodFetal period

Parental period is sub divided into 3 stages:

VARIOUS STAGES OF PARENTAL PERIOD

Initial period involves in the development of week 1.

Week 1 starts with fertilization and extends through the first cell divisions that produce an embryo with one germ layer.

INITIAL PERIOD

Embryonic period involves in the development of week 2 through 8Week 2 produce two germ layers.Week 3 produce three germ layers and folds those a recognizable three dimensional body form .Week 4 to through 8 are the period of organogenesis.

EMBRYONIC PERIOD

FETAL PERIODIt involves in the development after week 8 till birth.

In this period the organs grow larger and become more complex