Cleavage and blastocyst, Biology

Cleavage and Blastocyst

Even though the cleavage is complete and all the blastomeres are of more or less equivalent size. Synchronization of mitoses in the blastomeres is lost very early. Even the first two blastomeres may cleave at dissimilar rates; consequently, a 3 cell stage and subsequently stages of five, six, seven blastomeres and so forth are found. The result of the cleavage is a solid mass of cells a morula, where some cells are superficial and others lie inside, completely cut off from the surface through them enveloping cells.

In due course the superficial cells join to make a distinct epithelial layer. This layer provides rise to most of the extra embryonic parts (the embryonic membranes), serves to attach the embryo to the uterine wall, and mediates in the supply of nourishment to the embryo from the maternal body via the placenta. This outer layer of the mammalian embryo is termed as the trophoblast (the term trophe meaning nourishment). The cells lying in the interior are known as the inner cell mass (ICM), and it is these cells that provide material for the formation of the embryo proper. Hence they may, be referred to as the formative cells. Sooner or later a cavity appears inside the compact mass of cells of the morula. The cavity is formed of crevice that appears among the inner cell mass and the cells of the trophoblast. Fluid is imbided into this cavity, so that it enlarges. The trophoblast becomes lifted off most of the inner cell mass remaining attached to it on one side only. This side corresponds late to the dorsal side of the embryo. A mammalian embryo at this stage is termed as a blastocyst.

Posted Date: 1/25/2013 5:59:35 AM | Location : United States







Related Discussions:- Cleavage and blastocyst, Assignment Help, Ask Question on Cleavage and blastocyst, Get Answer, Expert's Help, Cleavage and blastocyst Discussions

Write discussion on Cleavage and blastocyst
Your posts are moderated
Related Questions
Foscarnet  (Foscavir)  Foscarnet is an alternative to ganciclovir and valganciclovir for treatment of CMV infection. It is approved for use in CMV retinitis, including progress

what is the mode of nutrition in tape worm

What is Bilateral Symmetry system? To review: all animals besides the sponges (Phylum Porifera) belong to the Eumetazoa. There are two groups within the Eumetazoa that possess

What does a two-direction arrow show in a chemical equation? The oxygen atoms share two pairs of electrons, as every atom needs two more electrons to fill the orbitals of its o

Preoperative antibiotics Preoperative antibiotics can decrease the incidence of infection after colorectal surgery; for elective operations, an oral regimen of neomycin (not a

Is sex too hot to handle???

You have identified a protein in a cell that you know that comes from the human body. With respect to that protein you have also determined that it allows sodium ions to go through

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4 Mode of feeding

Pollination Many flowering plants rely on animals such as bees, butterflies, moths, wasps, beetles, birds, and bats for pollination to produce fruit. Thirty percent of our food

What is Peripheral Vein Feeding Intravenous feeding is a method of  providing parenteral nutrition when a  patient cannot take in food or formula through the gastrointestinal