Blástula

Blástula is a term used in biology to describe the early stage of embryonic development in animals. It is formed after the process of fertilization, where the sperm cell fuses with the egg cell, creating a single cell called a zygote. The zygote undergoes several rapid mitotic divisions, resulting in a hollow ball of cells called a blastula. This stage is characterized by the formation of a blastocoel, a fluid-filled cavity that develops within the mass of cells.

The blastula stage is crucial as it sets the stage for the formation of the three germ layers: ectoderm, mesoderm, and endoderm. These layers will eventually differentiate into various tissues and organs during further development. The blastula is also the stage at which implantation into the uterine lining occurs in mammals, marking the beginning of pregnancy.

The blastula stage varies in duration depending on the species. In humans, it typically lasts from the two-cell stage until around day 5 after fertilization. During this time, the blastula undergoes significant changes, including the formation of the blastopore, a small opening that will eventually give rise to the digestive tract and other structures.

Understanding the blastula stage is essential for studying embryonic development and for medical research, particularly in areas related to reproductive biology and developmental disorders.