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This constitutes the so-called capsule of the space. Each lacuna is generally occupied by a single cell, but during the division of the cells, it may contain two, four, or eight cells. Lacunae are found between narrow sheets of calcified matrix that are known as lamellae (/ l ə ˈ m ɛ l i / lə-MEL-ee).
The theory of recapitulation, also called the biogenetic law or embryological parallelism—often expressed using Ernst Haeckel's phrase "ontogeny recapitulates phylogeny"—is a historical hypothesis that the development of the embryo of an animal, from fertilization to gestation or hatching (), goes through stages resembling or representing successive adult stages in the evolution of the ...
Human embryology is the study of this development during the first eight weeks after fertilization. The normal period of gestation (pregnancy) is about nine months or 36 weeks. The germinal stage refers to the time from fertilization through the development of the early embryo until implantation is completed in the uterus .
The embryogenic tree is a diagram which shows the temporal development of each of the cell lines in the embryo. When drawn on a piece of paper, this diagram takes the form of a tree, analogous to the evolutionary tree of life which illustrates the development of life on Earth. However, instead of each branch on this tree representing a species ...
In some of its facets human anatomy is closely related to embryology, comparative anatomy and comparative embryology, [1] through common roots in evolution; for example, much of the human body maintains the ancient segmental pattern that is present in all vertebrates with basic units being repeated, which is particularly obvious in the ...
Prenatal development (from Latin natalis 'relating to birth') involves the development of the embryo and of the fetus during a viviparous animal's gestation.Prenatal development starts with fertilization, in the germinal stage of embryonic development, and continues in fetal development until birth.
B.—Diagram of the female type of sexual organs. C. Greater vestibular gland, and immediately above it the urethra. cc. Corpus cavernosum clitoridis. dG. Remains of the left Wolffian duct, such as give rise to the duct of Gärtner, represented by dotted lines; that of the right side is marked w. f. The abdominal opening of the left uterine ...
The word somite is sometimes also used in place of the word metamere. In this definition, the somite is a homologously -paired structure in an animal body plan , such as is visible in annelids and arthropods .