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A megakaryocyte (from mega- 'large' karyo- 'cell nucleus' and -cyte 'cell') is a large bone marrow cell with a lobated nucleus that produces blood platelets (thrombocytes), which are necessary for normal clotting. In humans, megakaryocytes usually account for 1 out of 10,000 bone marrow cells, but can increase in number nearly 10-fold during ...
The megakaryoblast has a high nucleus to cytoplasm ratio with a nucleus that may be 3 to 5 times the size of the cytoplasm. The nucleus is generally oval, kidney shaped or lobed. Several nucleoli are visible, along with loose chromatin. [10] The chromatin may vary from cell to cell, ranging from fine to heavy and dense.
Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium ...
Genome size ranges (in base pairs) of various life forms. Genome size is the total amount of DNA contained within one copy of a single complete genome.It is typically measured in terms of mass in picograms (trillionths or 10 −12 of a gram, abbreviated pg) or less frequently in daltons, or as the total number of nucleotide base pairs, usually in megabases (millions of base pairs, abbreviated ...
Bone marrow comprises approximately 5% of total body mass in healthy adult humans, such that a person weighing 73 kg (161 lbs) will have around 3.7 kg (8 lbs) of bone marrow. [5] Human marrow produces approximately 500 billion blood cells per day, which join the systemic circulation via permeable vasculature sinusoids within the medullary ...
The bones were determined to be up to 47,500 years old. Until now, the oldest Homo sapiens remains from northern central and northwestern Europe were about 40,000 years old.
It is composed of 270 bones at the time of birth, [2] but later decreases to 206: 80 bones in the axial skeleton and 126 bones in the appendicular skeleton. 172 of 206 bones are part of a pair and the remaining 34 are unpaired. [3] Many small accessory bones, such as sesamoid bones, are not included in this.
This represents the size of a composite genome based on data from multiple individuals but it is a good indication of the typical amount of DNA in a haploid set of chromosomes because the Y chromosome is quite small. [7] Most human cells are diploid so they contain twice as much DNA (~6.2 billion base pairs).