Implantation - pre-embryonic development, Biology

Assignment Help:

Implantation - Pre-Embryonic Development

After entering the uterus and formation of ICM, the blastocyst starts to embed in the endometrium of the uterine wall. By one week after fertilization the trophoblast secretes enzymes which digest the tissues and blood vessels of the uterine wall. The invading trophoblast differentiates into two layers, the outer syncytiotrophoblast and the inner cellular layer. Like the syncytiotrophoblast swallows more blood vessels in the uterine wall lacunae develop in the syncytiotrophoblast that get filled up with blood from the mother and exchange of gases takes place here. So a primitive utero- placental circulation is established. This nourishes the embryo till the placenta is made. By the 10th day the blastocyst is totally embedded in the uterine wall.

This kind of implantation in which the embryo gets fully embedded is termed as interstitial implantation. The trophoblast begins to secrete human chorionic gonadotropin (HCG). HCG causes the corpus luteum to be maintained and to carry on to secrete estrogen and progesterone. Sometimes implantation may occur outside the uterus at some other location. In that case it is an ectopic pregnancy. The implantation site might be the fallopian tube or even the abdominal cavity. In ectopic pregnancy the embryo has to be surgically removed as if it is not done, it can lead to tuba1 rupture, internal bleeding, shock and possible death. At the beginning of the second week a small cavity appears between the trophoblast and ICM. This is the amniotic cavity that will grow around the embryo and later the foetus, It is a fluid filled cavity that act as an insulator against shocks, cold and heat. At similar time the ICM also differentiates into two layers, the upper epiblast which provides rise to the embryo and the lower hypoblast which gives rise to the extraembryonic membranes.


Related Discussions:- Implantation - pre-embryonic development

Functions of endosperm, Functions of Endosperm The tissue of young en...

Functions of Endosperm The tissue of young endosperm is rich in food materials and various growth hormones. It regulates the precise mode of embryo development and nourishes

Briefly describe about caramelization, Briefly describe about Caramelizatio...

Briefly describe about Caramelization? Caramelization results from the action of heat on sugars at about 175º C. At high temperatures, sugars dehydrate, break down and polymeri

Define terpene alcohols - non glyceride fractions, Define Terpene Alcohols ...

Define Terpene Alcohols - non glyceride fractions? Partly free, partly esterified e.g. ferulic acid; these are found in significant amounts in rice bran oil, wheal germ oil, so

Respiration.., different types of respiration system in different organisms...

different types of respiration system in different organisms

Economic significance - conservation of wildlife, Economic Significance - C...

Economic Significance - Conservation of Wildlife Certain wild species are important because of their actual or potential economic value to people. Wildlife resources provide p

Anthropodes, advantages of cuticle of anthropodes

advantages of cuticle of anthropodes

Skeletal tissue, what is the classification of skeletal tissue?

what is the classification of skeletal tissue?

Occurrence of jaundice, Occurrence of Jaundice Excessive production ...

Occurrence of Jaundice Excessive production of bilirubin - this occurs in some diseases due to destruction of large number of red blood cells in the liver. Obstruction to

Explain sound production - ethological approach in taxonomy, Explain Sound ...

Explain Sound production - Ethological Approach in Taxonomy The most used, ethological feature in identification is the sound produced by various species of animals. This is

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd