Morula
Historical document, translated for reference. It reflects medical knowledge of the 1920s–30s and is not medical advice.
Summary
The morula is an embryological term introduced by Haeckel to denote the final stage of cleavage when the embryo consists of a compact mass of cells. In typical cases, it has a spherical shape resembling a mulberry or raspberry.
Encyclopedia entry (1928–1936)
MORULA (diminutive from Latin morum - mulberry), an embryological term introduced by Haeckel for denoting the final stage of cleavage, when the embryo represents a compact bunch of cells (blastomeres). In typical cases (eggs with complete cleavage in many invertebrates and mammals) the M. has a spherical shape and resembles a mulberry or raspberry; in eggs with partial cleavage (fish, reptiles, birds) the compact mass of blastomeres lies on the surface of the yolk in the form of a disk or a flat-convex lentil. The stage of M. quickly passes into the next stage of blastula by the formation of a cavity inside the cellular mass. Sometimes the formation of the cavity begins earlier, in the process of cleavage; in such cases M. as a sharply delimited phase does not exist (see Cleavage, Blastula).
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“Morula.” Soviet Medical Encyclopedia. English translation of Bolshaya Meditsinskaya Entsiklopediya, 1st ed. (Moscow, 1928–1936), ed. N. A. Semashko. https://sovietmedicalencyclopedia.pages.dev/article/morula/