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

Biota of the neritic oceanic zone, Biota of the Neritic Oceanic Zone T...

Biota of the Neritic Oceanic Zone This zone constitutes 75 per cent of the total oceanic area and is relatively rich in species and high in productivity owing to factors such

Explain pr murmur characterstic and graham steel murmur, Explain PR Murmur ...

Explain PR Murmur characterstic and graham steel murmur? PR Murmur Characteristic: Blowing, decrescendo murmur heard loudest in 2nd and 3rd left intercostal space with increa

What is the constitution of the cartilaginous matrix, What is the constitut...

What is the constitution of the cartilaginous matrix? The cartilaginous matrix is made of collagen fibers, mostly collagen type II, and of proteoglycans, proteins associated to

Secondary and tertiary consumers - biotic components, Secondary and Tertiar...

Secondary and Tertiary Consumers - Biotic Components Besides there are animals which depend on herbivores for food and are called secondary consumers. Since secondary consumer

Meaning of cellular secretion, Cell secretion is the elimination to the ext...

Cell secretion is the elimination to the exterior of substances formed by the cell (for example, hormones, mucous, sweat, etc.)

How is the circulatory system of birds characterized, How is the circulator...

How is the circulatory system of birds characterized? Birds, as every vertebrate, have a closed circulatory system. The heart is same to the mammalian heart, having four chambe

What is the ecological role of earthworms, Q. What is the ecological role o...

Q. What is the ecological role of earthworms? Earthworms have an important ecological role as they eat decomposing organic material. They also dig tunnels in the subsoil allowi

Define regulation of water balance for the kidneys, Define Regulation of Wa...

Define Regulation of Water Balance For the kidneys? The kidneys are highly efficient conservators of body water. Although the kidneys filter 180 L of blood per day (125 ml / mi

Define nitrogen requirements in pregnancy and lactation, Define Nitrogen re...

Define Nitrogen requirements in Pregnancy and Lactation? The nitrogen accretion in the pregnant woman (assuming that the foetus weighs 3.3 kg at term), estimated by the Committ

Emphysema, Emphysema Emphysema is destructive changes in alveolar wall...

Emphysema Emphysema is destructive changes in alveolar walls and enlargement of air spaces distal to the terminal non-respiratory bronchioles. It is characterized physiolog

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