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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 lacuna model is a tool for unlocking culture differences or missing "gaps" in text (in the further meaning). The lacuna model was established as a theory by Jurij Sorokin and Irina Markovina (Russia), further developed by Astrid Ertelt-Vieth and Hartmut Schröder (Germany) and practical research tested in ethnopsycholinguistics (Igor Panasiuk 2000 and 2005), Russian studies (Vladimir ...
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 40 weeks. The germinal stage refers to the time from fertilization through the development of the early embryo until implantation is completed in the uterus .
First, there is an outpocketing of the neural tube called optic vesicles.Development of the optic vesicles starts in the 3-week embryo, from a progressively deepening groove in the neural plate called the optic sulcus.
Drawing of the head of a four-week-old human embryo. From Gray's Anatomy.. Embryo drawing is the illustration of embryos in their developmental sequence.In plants and animals, an embryo develops from a zygote, the single cell that results when an egg and sperm fuse during fertilization.
The development of the nervous system in humans, or neural development, or neurodevelopment involves the studies of embryology, developmental biology, and neuroscience. These describe the cellular and molecular mechanisms by which the complex nervous system forms in humans, develops during prenatal development, and continues to develop postnatally.
The main theory states that formation of the membranes of the yolk sac begins with an increase in production of hypoblast cells, followed by different patterns of migration. On day eight, the first portion of hypoblast cells begin their migration and make what is known as the primary yolk sac, or Heuser's membrane (exocoelomic membrane).
The rete testis (/ ˈ r iː t i ˈ t ɛ s t ɪ s / REE-tee TES-tis; pl.: retia testes) is an anastomosing network of delicate tubules located in the hilum of the testicle (mediastinum testis) that carries sperm from the seminiferous tubules to the efferent ducts.