The fluid-filled cavity in a tertiary ovarian follicle is termed

The fluid-filled cavity within the granulosa cells in a tertiary ovarian follicle is termed antrum. It provides a space for the oocyte to grow and mature, and it also helps to regulate the hormonal environment within the follicle.

The theca is a layer of cells that surrounds the ovarian follicle and plays a role in the production of hormones. The theca is located outside of the granulosa cells. Theca interna and granulosa cells produce oestrogens.

The acrosome is a specialized organelle found in the head of a sperm cell. It is a cone-shaped structure that contains enzymes that are used to help the sperm fertilise an egg.

The endometrium during pregnancy differentiates into decidua. The decidua is thicker and more vascularised than the endometrium, and it plays a crucial role in providing nutrients and support to the developing foetus. The decidua basalis is in direct contact with the implanting embryo. It forms the maternal part of the placenta. The decidua capsularis is the outer layer of the decidua that surrounds the embryo. The decidua parietalis lines the rest of the uterus and is not in direct contact with the embryo.