The pluripotent, undifferentiated cells in the bone marrow that give rise to the formed elements are called stem cells.
Pluripotent stem cells have the ability to undergo self-renewal and to give rise to all cells of the tissues of the body. However, this definition has been recently complicated by the existence of distinct cellular states that display these features.
There are two types of pluripotent stem cells :
- Embryonic stem cells (ESCs)
- Induced pluripotent stem cells
Embryonic stem cells are derived from the inner cell mass (ICM) of pre-implantation embryos and can be indefinitely maintained and expanded in the pluripotent state in vitro. Pluripotent stem cells can also be obtained by inducing dedifferentiation of adult somatic cells through a recently developed in vitro technology, known as cell reprogramming.
Similarly to Embryonic stem cells , Induced pluripotent stem cells can be expanded indefinitely and they are capable to differentiate in all the derivatives of the three germ layers.
Another intriguing features of being pluripotent is its reliance on gene expression heterogeneity.
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Heart rate is controlled by the two branches of the autonomic (involuntary) nervous system. The sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). The sympathetic nervous system (SNS) releases the hormones (catecholamines - epinephrine and norepinephrine) to accelerate the heart rate. The parasympathetic nervous system (PNS) releases the hormone acetylcholine to slow the heart rate. Such factors as stress, caffeine, and excitement may temporarily accelerate your heart rate, while meditating or taking slow, deep breaths may help to slow your heart rate.
The correct answer is Protozoa.
A class of single-celled, non-prokaryotic organisms known as protozoa.These could either be parasitic or free-living in nature. These are heterotrophs that procreate via binary fission in an asexual manner. Numerous unrelated or tangentially related organisms make up the Protozoa. Sarcodina, Flagellates, Ciliates, and Sporozoans are the four main divisions. There are two stages in the life cycle of certain protozoa: the proliferative stage (trophozoites), and the resting stage (cysts). Trophozoites are the proliferative stage of the protozoa, which is when they divide and reproduce. The protozoa can tolerate adverse environmental circumstances like toxic chemicals, intense heat, and nutrition and water shortages because of their resting cyst shape.
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The main function of a plant cell wall is to protect the cell.
