Female Reproductive Process — NEET Biology

Which of the following statements regarding early human embryonic development and implantation are correct? S1: The fusion of male and female gametes, known as fertilisation, predominantly occurs in the ampullary region of the oviduct, followed by the initiation of mitotic divisions (cleavage) as the zygote moves towards the uterus. S2: The blastocyst, formed by repeated divisions of the zygote, comprises an outer layer called trophoblast and an inner group of cells known as the inner cell mass; the inner cell mass is responsible for direct attachment to the uterine endometrium during implantation. S3: The endometrium, the inner glandular layer of the uterus, is essential for the implantation of the blastocyst and undergoes cyclical changes under hormonal influence to support pregnancy. S4: Following implantation, finger-like projections called chorionic villi develop from the trophoblast, which, along with uterine tissue, form the structural and functional unit of the placenta, acting as an endocrine tissue. S5: The determination of the embryo's sex is exclusively controlled by the type of sex chromosome (X or Y) carried by the ovum that successfully fertilises the sperm. S6: The inner cell mass, post-implantation, differentiates to form the ectoderm and endoderm initially, with the mesoderm appearing later between them, collectively giving rise to all tissues and organs.