embryologii

Embryology is a branch of biology that studies the development of organisms from fertilization to birth or hatching. It covers the structural, cellular, and molecular changes that shape embryos, as well as the ways in which genetic and environmental factors influence development. While often centered on animals, embryology also concerns plant development in the seed and embryo context.

Historically, embryology emerged from debates on epigenesis versus preformation, and is associated with figures such as Aristotle, Karl Ernst von Baer, and Hans Spemann. Von Baer established early comparative descriptions and the idea that embryos diverge from a common form at early stages. The 20th century saw advances in experimental embryology, including the Spemann–Mangold organizer experiment, which showed that a portion of the embryo can induce development of surrounding tissues. Modern embryology integrates genetics, cell biology, and molecular biology.

Key stages include fertilization, cleavage and blastula formation, gastrulation, neurulation, and organogenesis. These stages involve cell divisions, migration, signaling, and tissue interactions that establish axes, germ layers, and organ primordia. Fate mapping and lineage tracing reveal how specific cells contribute to adult structures.

Researchers use model organisms such as mice, zebrafish, fruit flies, and nematodes, along with in vitro culture systems. Techniques include microscopy, embryo culture, gene editing, transcriptomics, and imaging of developmental processes.

Applications of embryology include understanding congenital abnormalities, improving assisted reproductive technologies, stem cell biology, and regenerative medicine. The field overlaps with teratology, evo-devo, and developmental biology, emphasizing how developmental processes evolve and vary across species.