Final answer:
Cohesin proteins are responsible for holding chromatids together following crossing over, and are particularly located at the centromere, playing a key role in chromosome segregation.
Step-by-step explanation:
The points that hold chromatids together following crossing over are the cohesin proteins. During the first prophase of meiosis, when chromosomes condense and the nuclear envelope fragments, homologous chromosomes bind together to form a structure known as a tetrad.
The alignment and connection of these chromosomes are maintained by a protein lattice known as the synaptonemal complex and the cohesin proteins located particularly at the centromere. The cohesin proteins play a pivotal role in the correct segregation of the chromosomes during cell division by assisting in the proper pairing and separation of sister chromatids.