Development of Inner Cell Mass Development of inner cell mass differentiated into; 1. Amnion layer of embryo cell 2. Umbilical cord 3. Foetus After implantation, 2 cavity appear in inner cell mass. 1. Amniotic cavity/ amniotic sac contains amniotic fluid Amnion membrane forming fluid filled cavity (amniotic sac that enclose the embryo). 2. Yolk sac Before placenta form, yolk cell provide nutrition and gas exchange between mother and developing embryo.
Category: Female Reproductive Organs
chorion
Chorion and Chorionic Villi Chorion is outermost fetal membrane around embryo. After implantation trophoblast differentiated into; 1. Outer layer Syncytitrophoblast 2. Inner layer Cytotrophoblast (Langhan’s layer) Chorion layer made up of trophoblast and mesoderm. Chorion villi surround developing ovum. Villi overlying decidua basalis continue to grow and expand called chorion frondosum and form placenta. Mesodermal tissue (connecting stalk) connects inner cell mass to chorion and will form umbilical cord later on.
stages of embryonic development
Embryonic development After zygote formation, mitotic devision of zygote producing two blastomere. 16 cell stage called morula (solid mass of blastomere). Morula Two cell stage (called morula) reached approximately 30 hours after fertilization. Each blastomere; equal cytoplasmic and chromosome number. Morula after spending about 3 days in uterine tube enters uterine cavity through narrow uterine ostium on 4th day in the 16-64 cell stage. Central cell of morula known inner cell mass (form embryo). Peripheral cell called outer cell mass (form protective and nutritive membranes
stages of implantation
Implementation Implementation stages are; Stage 1 Apposition Stage 2 Adhesion Stage 3 Penetration Stage 4 Invasion 1. Apposition Pinopods; long finger like projection (microvilli) form endometrial cell surface. Endometrial fluid secreted by endometrial gland cells, pinopods absorb endometrial fluid. Endometrial fluid rich in glycogen and mucin provide nutrition to blastocyst. 2. Adhesion (Attachment) Adhesion of blastocyst to endometrium occurs through adhesion molecules like integrin, selectin and cadherin (glycoprotein). 3. Penetration and invasion Trophoblast cells of blastocyst attach to endometrial epithelium. Invasive trophoblast cells cross endometrial
inner cell mass
Development of Inner Cell Mass Development of inner cell mass differentiated into; 1. Amnion layer of embryo cell 2. Umbilical cord 3. Foetus After implantation, 2 cavity appear in inner cell mass. 1. Amniotic cavity/ amniotic sac contains amniotic fluid Amnion membrane forming fluid filled cavity (amniotic sac that enclose the embryo). 2. Yolk sac Before placenta form, yolk cell provide nutrition and gas exchange between mother and developing embryo. Inner Cell Mass Inner cell mass known as embryoblast. Embryoblast development of embryo embryonic stem
trophoblast
Trophoblast (Trophectoderm) Trophoblast is cell of blastocyst. Trophoblast differentiated into; 1. Cytotrophoblast or Langhan’s layer 2. Syncytitrophoblast Local cytokines regulate invasion of the cytotrophoblast in decidua.
morula
Morula Two cell stage (called morula) reached approximately 30 hours after fertilization. Each blastomere; equal cytoplasmic and chromosome number. Morula after spending about 3 days in uterine tube enters uterine cavity through narrow uterine ostium on 4th day in the 16-64 cell stage. Central cell of morula known inner cell mass (form embryo). Peripheral cell called outer cell mass (form protective and nutritive membranes of embryo).
blastocyst
Blastocyst On 4th and 5th day morula in uterine cavity covered by film of mucus. Fluid pass through canaliculi of zona pellucida; separate cells of morula called blastocyst. Due to blastocyst enlargement zona pellucida become stretched, thinned and gradually disappears. Lysis of zona pellucida and escape of embryo called zona hatching. Outer side of morula become trophectoderm (adhesion of blastocyst to uterine epithelialium. Inner side of morula become inner cell mass. Changes in Blastocyst Trophoblast cell adjacent to inner cell mass primarily involved in adhesion
chorion and amnion
Chorion and Chorionic Villi Chorion is outermost fetal membrane around embryo. After implantation trophoblast differentiated into; 1. Outer layer Syncytitrophoblast 2. Inner layer Cytotrophoblast (Langhan’s layer) Chorion layer made up of trophoblast and mesoderm. Chorion villi surround developing ovum. Villi overlying decidua basalis continue to grow and expand called chorion frondosum and form placenta. Mesodermal tissue (connecting stalk) connects inner cell mass to chorion and will form umbilical cord later on. Development of Inner Cell Mass Development of inner cell mass differentiated into; 1. Amnion
layers of decidua
Decidua Decidua is modified or specialized mucosal lining of endometrium during pregnancy. Layers of Decidua 3 layers of decidua present; 1. Compact outer layer (stratum compactum) Stratum compactum contain contain compact mass of decidual cells, gland ducts, dilated capillaries. 2. Intermediate spongy layer (stratum spongiosum) Stratum spongiosum contains dilated uterine glands, decidual cells and blood vessels. 3. Thin basal layer (stratum basalis) Stratum basalis is regeneration of mucus coat. After the interstitial implantation of blastocyst into compact layer of decidua differentiated; 1. Decidua basalis or
