The spelling of "egg cell" is straightforward, and its pronunciation is indicated using the International Phonetic Alphabet (IPA). The first part of the word "egg" is pronounced as "ɛɡ," with the "e" sounding like the "e" in "bed" and the "g" being sounded as "g." The second part of the word, "cell," is pronounced as "sɛl," with the "c" being pronounced as "s" and the "e" sounding like the "e" in "bed." Thus, "egg cell" is pronounced as "ɛɡ sɛl."
An egg cell, also known as oocyte or ovum, is a fundamental component of sexual reproduction in animals, specifically in females. It refers to the largest cell produced in the ovaries of females, typically enveloped by a protective outer layer called the zona pellucida. This specialized cell is responsible for providing half of the genetic material necessary for the creation of a new individual when fertilized by a sperm cell during fertilization.
Structurally, an egg cell is characterized by its spherical shape, rich cytoplasm with numerous organelles, and a prominent nucleus containing the genetic material in the form of DNA. It is considerably larger than the sperm cell, designed to encompass sufficient energy reserves and vital molecules necessary for the initial stages of embryonic development. The egg cell is immobile and mainly relies on the movement elicited by the cilia lining the fallopian tube to be passed into the uterus after being released by ovulation.
In some animal species, such as reptiles, birds, and monotremes, the egg cell is released from the ovary before fertilization and is laid externally to undergo incubation. Conversely, mammals' egg cells are typically fertilized internally and have evolved the ability to undergo embryonic development within the mother's body. This evolution of internal fertilization has allowed mammals to further protect and nourish the developing embryos, fostering the establishment of viviparity.
The word "egg" can be traced back to Old Norse, where it was spelled "egg". The Old Norse word likely originates from Proto-Germanic "*ajją" or "ajjąz", which meant "egg" or "borne in the womb" in the context of birds or reptiles. This Proto-Germanic root is believed to have come from the Proto-Indo-European "*ōwyóm" or "*ōwyós", meaning "bird" or "egg". The word "cell" comes from Latin "cella", meaning "small room" or "compartment". In the context of biology, "cell" refers to the basic structural and functional unit of living organisms.