Morula

A morula (Latin, morus: mulberry) is an early-stage embryo consisting of a solid ball of cells called blastomeres, contained within the zona pellucida. The blastomeres are the daughter cells of the zygote, and in the human by day 4 after fertilisation the blastomeres number from 16–32 and the ball of cells is called the morula.[1][2]

Morula
Blastulation. 1 - morula, 2 - blastocyst.
First stages of segmentation of a fertilized mammalian ovum. Semidiagrammatic. z.p. Zona pellucida. p.gl. Polar bodies. a. Two-cell stage. b. Four-cell stage. c. Eight-cell stage. d, e. Morula stage.
Details
Days3
PrecursorZygote
Gives rise toBlastula, Blastocyst
Identifiers
MeSHD009028
TEE2.0.1.2.0.0.11
Anatomical terminology

After day 4 in the human embryo, the morula at about the 30–cell stage begins to take in fluid. The fluid comes about from sodium-potassium pumps (on trophoblasts) that pump sodium into the morula, drawing in water from the maternal environment to become blastocoelic fluid. Hydrostatic pressure of the fluid creates a large cavity in the morula called a blastocoel or blastocyst cavity. Embryoblast cells form a compact mass of cells at the embryonic pole on one side of the cavity, called the inner cell mass. The trophoblast is organized into a thin sheet of tightly adhered epithelial cells. The embryo is now termed a blastocyst.[1]


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