Read the passage and answer the following question:
The blastomeres in the blastocyst are arranged into an outer layer called trophoblast and an inner group of cells attached to trophoblast called the inner cell mass. The trophoblast layer then gets attached to the endometrium and the inner cell mass gets differentiated as the embryo. After attachment, the uterine cells divide rapidly and covers the blastocyst. As a result, the blastocyst becomes embedded in the endometrium of the uterus . This is called implantation and it leads to pregnancy. After implantation, finger-like projections appear on the trophoblast called chorionic villi which are surrounded by the uterine tissue and maternal blood. The chorionic villi and uterine tissue become interdigitated with each other and jointly form a structural and functional unit between developing embryo (foetus) and maternal body called placenta. The placenta facilitate the supply of oxygen and nutrients to the embryo and also removal of carbon dioxide and excretory/waste materials produced by the embryo. The placenta is connected to the embryo through an umbilical cord which helps in the transport of substances to and from the embryo. Placenta also acts as an endocrine tissue and produces several hormones like human chorionic gonadotropin (hCG), human placental lactogen (hPL), estrogens, progestogens, etc.
In the later phase of pregnancy, which hormone is secreted by the ovary?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Relaxin
During pregnancy several new hormones appear in the mother’s blood. Most of them come from the placenta, such as hCG and hPL. Relaxin is different: it is secreted by the ovary, and only in the later phase of pregnancy. Like hCG and hPL, relaxin is produced in women only during pregnancy. Oxytocin is released from the maternal pituitary and LH from the anterior pituitary; prolactin only rises in the mother’s blood during pregnancy. None of them is secreted by the ovary.
NCERT Extract:
Pregnancy and Embryonic Development – “… Placenta also acts as an endocrine tissue and produces several hormones like human chorionic gonadotropin (hCG), human placental lactogen (hPL), estrogens, progestogens, etc. In the later phase of pregnancy, a hormone called relaxin is also secreted by the ovary. Let us remember that hCG, hPL and relaxin are produced in women only during pregnancy. In addition, during pregnancy the levels of other hormones like estrogens, progestogens, cortisol, prolactin, thyroxine, etc., are increased severalfolds in the maternal blood.”