Question

The outermost layer of a blastocyst is called
(a) ectoderm
(b) mesoderm
(c) endoderm
(d) trophoblast

Answer 1

Answer:

$</p><p>\huge{\blue{\boxed{\boxed{\red{\ulcorner{\mid{\overline{\underline{\bf{Answer:-}}}}}}\mid}}}}$

The outermost layer of a blastocyst is called Trophoblast.

Answer 2

Correct option is

➢ d). Trophoblast

Trophoblast cells refer to cells from the trophoblast outside the embryo that have a trophoblastic function. The trophoblast cells grow rapidly, forming many hairy protrusions on the surface of the embryo sac, called "villi."

The trophoblast begins with only one layer of flat cubic cells, which gradually differentiate into two layers when forming villi. The inner layer and interstitial contact, formerly known as "Langhans cells", is now called "cyto-trophoblast". The outer layer is in contact with the decidua of the uterus. It used to be called "zygote", but now it is called "syncytio-trophoblast". After further understanding, normal trophoblast cells have certain unique biological characteristics, which are closer to malignant tumors than normal tissues. Trophoblast cells eccentrically invade the endometrium, myometrium and spiral artery from the place surrounding the embryo sac to establish uterine placental circulation. Trophoblast cells are widely spread in the blood throughout normal pregnancy due to invasion of blood vessels, mainly to the lungs, and disappear after delivery. Trophoblast cells covered with chorionic villi are called "villi trophoblast cells". Trophoblast cells in other parts of the uterus are called "trophoblast trophoblast cells". Extra-villous trophoblast cells form a trophoblast column that traverses the villus gap from the base of the villus anchor; infiltrate the decidua surrounding the embryo sac bottom to form a trophoblast shell, which partially evolves into a smooth villi epithelium; a spiral artery that invades the placenta bed ; Infiltrate the muscular layer beneath the implant site.