Alecithal is a term used in biology that refers to organisms that lack yolk in their eggs. The word consists of three syllables, "a-le-ci-thal," with primary stress on the second syllable. The first syllable "a" is pronounced as in "apple," the second syllable "le" is pronounced as in "lens," and the third syllable "ci-thal" is pronounced as in "sigh-thal." The IPA transcription for Alecithal is /ˌeɪləˈsɪθəl/. This word is commonly used in embryology to describe the development of embryos of different animal species.
Alecithal is an adjective used in biology to describe an organism, typically an animal, that lacks yolk in its eggs. The term is derived from the Greek words "a," meaning without, and "lekithos," meaning yolk.
In reproduction, most animals produce eggs that contain yolk, a nutrient-rich substance that provides nourishment to the developing embryo. However, in alecithal organisms, the eggs do not contain any significant amount of yolk. This lack of yolk means that the developing embryo must rely on alternative sources for nutrition, such as uterine secretions or direct absorption from the mother.
Alecithal organisms are commonly found in certain groups of animals, including mammals and fish. In mammals, such as humans, the eggs are considered alecithal as they lack a visible yolk, and instead, rely on the mother's body for nourishment during pregnancy. Similarly, in fish species, alecithal eggs are released into water, where the embryos obtain their nutrition from surrounding sources.
The absence of yolk in alecithal eggs can have significant physiological implications for the developing organisms, as they must adapt to obtain their nutritional requirements from alternative sources. These adaptations can vary greatly among different species, reflecting the diverse strategies employed by alecithal animals to ensure the successful development of their offspring.
Without yolk, noting ova, if such exist, in which there is no deutoplasm; in general, noting the mammalian ovum in which there is no distinct yolk.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
The word "alecithal" is derived from the combination of two Greek roots: "a-" which means "without" or "not", and "lekythos" which refers to an oil flask or egg. The word "alecithal" is used in biology to describe eggs that lack yolk, hence the combination of these Greek roots accurately reflects its meaning.