👉 The term "heliacally" refers to a process where an egg is fertilized by sperm. This occurs when one of the sperm cells penetrates the outermost layer of the egg, known as the zona pellucida, and attaches itself to the endoplasmic reticulum (ER), which is the innermost part of the cell membrane. The fertilized egg then begins its journey through the cytoplasm, where it develops into a zygote.