A preimplantation embryo of about 150 cells produced by cell division following fertilization. The blastocyst is a sphere made up of an outer layer of cells (the trophoblast), a fluid-filled cavity (the blastocoel), and a cluster of cells on the interior (the inner cell mass).
The fluid-filled cavity inside the blastocyst, an early, preimplantation stage of the developing embryo.
The blastula is a hollow sphere of cells, referred to as blastomeres, surrounding an inner fluid-filled cavity called the blastocoele formed during an early stage of embryonic development in animals. Embryo development begins with a sperm fertilizing an egg to become a zygote which undergoes many cleavages to develop into a ball of cells called a morula. Only when the blastocoel is formed does the early embryo become a blastula. The blastula precedes the formation of the gastrula in which the germ layers of the embryo form.
Bone Marrow Stromal Cells:
A population of cells found in bone marrow that are different from blood cells, a subset of which are multipotent stem cells, able to give rise to bone, cartilage, marrow fat cells, and able to support formation of blood cells.
Bone Marrow Stromal Stem Cells (skeletal stem cells):
A multipotent subset of bone marrow stromal cells able to form bone, cartilage, stromal cells that support blood formation, fat, and fibrous tissue.
In the anatomy of humans and of many other vertebrates, the brainstem (or brain stem) is the posterior part of the brain, adjoining and structurally continuous with the spinal cord.