If the sperm cell fertilises the ovum, and implantation does not occur, then the corpus luteum degenerates and it turns into corpus albicans, stopping progesterone secretion. If fertilisation occurs and implantation also, the syncytiotrophoblast, the "root part" of the blastocyst (one of the early structures originated from the zygote), produces a hormone that is called <span>human chorionic gonadotropin (hCG). The hCG is what makes the corpus luteum keep secreting progesterone and maintain itself. The progesterone will then help keep the endometrium and, therefore, allow the development of the embryo to happen.</span>
B temperature and precipitation
Answer:
Spinal cord is a colon of nerve tissue that runs from the base of the skull to the center of the back.
Its function is to act as a highway communication between the body and the brain.
Explanation:
The benefits are Beaches are better protected against erosion.
Trenches created in the ocean encourage species growth.
WhatWhat are the advantages and disadvantages of beach nutrition?
Since nutrition just reduces the consequences of erosion and does not address its origins, it is usually a recurrent procedure. An agreeable setting lengthens the time between nutrient projects, cutting costs. On the other hand, a high rate of erosion might make nutrition unprofitable.
Sea turtles and rare and endangered birds alike depend on healthy beach and dunes systems. Important wildlife habitat areas that are endangered by erosion are provided by maintaining nourished beaches.
To learn more about Beaches refer
brainly.com/question/15524787?
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Answer:
Helper T cells are arguably the most important cells in adaptive immunity, as they are required for almost all adaptive immune responses. They not only help activate B cells to secrete antibodies and macrophages to destroy ingested microbes, but they also help activate cytotoxic T cells to kill infected target cells.
Explanation:
Helper T cells become activated when they are presented with peptide antigens by MHC class II molecules, which are expressed on the surface of antigen-presenting cells (APCs). Once activated, they divide rapidly and secrete cytokines that regulate or assist the immune response.
