The correct answer is the trophoblast forms two distinct layers.
Under usual conditions, fertilization takes place in one of the fallopian tubes, then the fertilized egg starts to produce its path towards the uterus. By about the fifth day of conception, the embryo ultimately reaches the uterus and gets the implant in the uterine lining or endometrium.
During week II of implantation, the trophoblast layer gets involved by combining with the uterine wall, and during this time the layer of trophoblast differentiates and proliferates into two different layers, that is, cytotrophoblast and syncytiotrophoblast.
Answer:
D: 20
Explanation:
The body needs 20 different amino acids to maintain good health and normal functioning. Hope this helps!
Most of the organisms (Living things/Biotic) need nonliving (abiotic) things to live in, such as caves, tunnels, under rocks (for the smaller ones.), water, etc.
It's the carpel that has three parts to it: the stigma — the sticky tip that catches pollen, the style — where the polled goes through to the ovaries — where the ovules are stored, and the ovules are what develop into seeds during fertilization.