Ovaries & Oviducts: The ovaries store and release ova. The oviducts (Fallopian tubes) are lined with ciliated cells that sweep the ovum toward the uterus; this is the primary site of fertilization.
Uterus & Cervix: The uterus is a muscular organ with a nutrient-rich lining (endometrium) where a fertilized egg implants. The cervix is a ring of muscle at the base that supports the fetus during pregnancy.
Vagina: A muscular canal that receives the penis during intercourse and serves as the birth canal during delivery.
Sperm Transit: Following ejaculation, sperm swim through the cervix and uterus into the oviducts, propelled by their flagella and guided by chemical signals.
Gamete Fusion: Fertilization occurs when a single sperm penetrates the outer layers of the ovum and their haploid nuclei fuse in the oviduct.
Mitotic Expansion: The resulting zygote begins immediate cell division via mitosis as it travels toward the uterus for implantation, eventually forming an embryo.
Gamete Motility: Sperm are highly motile using a flagellum and numerous mitochondria for energy, whereas ova are large, non-motile, and rely on ciliated movement in the oviduct.
Nutritional Content: The egg cell contains significant cytoplasm and food stores to support the initial stages of embryonic growth before the placenta develops.
Anatomical Pathways: Males use a shared exit for the excretory and reproductive systems, while the female reproductive and urinary tracts are entirely separate.
Site Identification: Always specify the oviduct as the site of fertilization; many students incorrectly name the uterus, which is only the site for implantation and development.
Numerical Precision: Be prepared to identify chromosome numbers: Gametes are haploid (), and zygotes/body cells are diploid ().
Adaptation Mapping: When describing sperm, link the high mitochondrial density specifically to the requirement for ATP to power the flagellum for swimming.
