fertilized egg
Noun: A fertilized egg is the initial developmental stage of an animal organism, formed immediately after a sperm cell successfully unites with an egg cell (ovum). This single cell contains the complete genetic blueprint from both parents and marks the beginning of embryonic development.
The term "fertilized egg" is used specifically in biological and medical contexts to describe the very first cell of a new organism, prior to its division and differentiation. * In higher animals (like mammals), this stage quickly progresses through cell division to form an embryo and later a fetus. * In many lower animals (like insects or amphibians), development from the fertilized egg leads directly to a larval stage.
- Scientists observed the fertilized egg dividing under the microscope.
- The process begins when a fertilized egg implants itself in the uterine wall.
- In frogs, the fertilized egg develops into a tadpole.
- Zygote: This is the precise scientific synonym for a fertilized egg before it begins to divide.
- The term is often used in discussions about reproductive biology, embryology, and ethics.
- Zygote (n): The scientific term for a fertilized egg cell before cleavage.
- Embryo (n): The developing organism from the first cell division until the major structures are formed (in humans, approximately the first 8 weeks).
- Blastocyst (n): An early stage of mammalian embryo development, following the morula stage.
- Fertilization (n): The process by which a sperm and an egg unite to form a fertilized egg.
- Zygote
- Oosperm (a less common technical term)
The core meaning is the single-celled starting point of a new animal life. The subsequent developmental path—whether it becomes an embryo/fetus or a larva—is implied by the context of the organism being discussed. The term itself refers strictly to the stage immediately following the fusion of gametes.
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an animal organism in the early stages of growth and differentiation that in higher forms merge into fetal stages but in lower forms terminate in commencement of larval life
