Barsukov N.P., Kolbasina R.A.
Crimea state medical
university named after S. I. Georgievsky, Simferopol.
The formation
of the placental
barrier structures in
the dynamics of intracellular and interstitial correlations in the early stages
of embryogenesis.
Considering the special
role of the trophoblast in the process of embryo implantation and trophic in
the early stages of embryogenesis acquires undoubted interest to study the
formation of intercellular at first, and later interstitial relationships in emerging
structures of gemoplatsentarnogo barrier. We have analyzed the slides 4.5-day human embryo
"Crimean girl" which trophoblast consists of a single layer of oval
unequal in size and shape of cells - of different tinctorial properties of
nuclei and cytoplasm.
Pellucid zone is already out, so the individual
blastomeres protrude above the surface of trophoblastic wall of the germinal
vesicle.
The blastocyst is located
in the lumen of the fallopian tube. The mucosa is lined with the latest high
cylindrical cells with oval nuclei and cytoplasm were stained intensely, with
lots vacuoles, demonstrating its high secretory activity.
It proofs that in the period of
the embryo promoting the oviduct between it and the parent organism is already
established at this early stage of embryogenesis such relationships that lead
to a marked increase not only the secretory processes in the oviduct epithelial
cells, but also the hyperemia of their vascular system, and, apparently
increased permeability of blood capillary walls, and this leads to swelling of
connective stroma endosalpinx.
Pretty soon (on the 6th day of embryogenesis) in the
trophoblast of blastocyst happen quite noticeable qualitative and quantitative
changes that are associated with its upcoming implantation. At the embryonic
pole of
blastodermic bubble proliferation of trophoblast cells is increased, causing it to become a multilayer structure. This is the pole of blastocyst implantation.
According to microscopic
examination, it is in the isthmic part of the oviduct in the depth of the
wrinkles of his mucosa . In it the degree of development of the structures
forming the wall of the blastocyst, are distinctly different embryonic and
extraembryonic pole.
At the embryonic pole
reveals the inner cell mass of the embryo, which is closely adherent to the
trophoblastic elements, and therefore a clear boundary between embryonic and
trophoblastic blastomeres is not defined.
The nuclei of blastomeres
embryoblast more hromofilny and are large in size than the trophoblastic
blastomeres.
Pellucid zone, limiting the
amount of the blastocyst in the initial stage of development, already absent,
due to which many blastomeres trophoblast protrude above the general surface of
the embryo. The size and shape of trophoblastic blastomeres varies. Most of
them are oval with rounded or elongated nuclei are localized in the center of
the cells.
Some cells become
flattened shape. Blastomere nuclei characteristic of trophoblast implantation
pole is lighter color due to their chromatin dispersion, as compared with those
in the cells of the blastocyst extraembryonic pole indicating a higher
functional activity of these cells, which is connected, generation of
tissue-dissolving enzymes providing embryo implantation.
Interstitial relations developing between fetal and maternal
tissues at the end of the second week of embryonic development, characterized
by the fact that the introduction of the embryo into the thickness of the
endometrium, the latter corresponds to a pronounced swelling of connective
tissue elements, dilation of blood capillaries in them, stasis of blood in
them, elevated leukocyte reaction .
Very soon, on the 17th
day of embryogenesis, qualitative and quantitative changes in the chorion
become even more pronounced. As the analysis of chorionic membrane 17-day human
embryo "Crimea", the entire surface of the membranes it is evenly
covered with chorionic villi, which are found among small, medium and large.
The wall of the membranes
is a chorionic plate, characterized by the presence of connective tissue basis in it,
covered with two layers trophoblast. From the chorionic plate depart numerous
stem villi, which have repeatedly dichotomous branched . Comparing the features of the
structure of chorionic membrane of human embryos 14 - and 17-day-old, it should
be noted that within a relatively short period of time it is a progressive
morphological transformations aimed at providing more and more increasing need
for trophic of
the developing embryo.
This process is accompanied by an increase in the metabolism
of all the structural components of chorion and their interaction with each
other.
The relationship between fetal and maternal tissues become
more complex .
Analysis of serial sections of fetal bladder 17 - day human
embryo "Crimea" showed that when abrasio between the chorion villi at
one of the poles of fetal bladder in the histological sections were maternal
tissues, including the perfectly preserved section of the deep endometrial
glands lined by epithelium cell height which varies from low to high prismatic.
Among his cell at the
overview coloring at least two diverse forms, which differ in the chromophilic
cytoplasm is detected. In some epithelial cells it is light, and in the other -
dark.
Gland epithelium rests on a clearly contoured basement
membrane, beneath which is the lamina propria of the uterus. It is
characterized by swelling of the stroma and the presence of highly advanced
blood capillary, crowded maternal blood.