The tiny embryo is located at the end of the micropyle. It has an open micropyle (hole in the shell) which may let in mould. They contain a single ovule with the micropyle directed downwards. In general goussians have thin walled oocysts lacking a micropyle, which contain four bivalved sporocysts. The radicle emerges from a seed through the micropyle. The micropyle has two openings and is therefore called a bistomal micropyle. Surrounding the megagametophyte are (one or) two integuments, which form an opening called the micropyle. The seeds have a black, crustaceous testa and curved, beak-like micropyle. A micropyle is located at the very top. Just below it is a small pore, representing the micropyle of the ovule. During germination, the seedling's radicle emerges through the micropyle. A distinct convex micropyle is usually present at one end of the oocyst. In angiosperms, only a pollen tube enters the micropyle. In plant ovules, the chalaza is located opposite the micropyle opening of the integuments. The micropyle opening allows the pollen (a male gametophyte) to enter the ovule for fertilization.