Aetna CEO: Obamacare In A 'Death Spiral' Heading Into 2018. Aetna and Humana have called off their deal amid government concerns over competition. Here's a look back at six pivotal moments that led to this. Aetna and Humana have called off their deal amid government concerns over competition.
For the plant genus, see Synapsis (plant). Synapsis (also called syndesis) is the pairing of two homologous chromosomes that occurs during meiosis. It allows matching-up of homologous pairs prior to their segregation, and possible chromosomal crossover between them. Synapsis takes place during prophase I of meiosis.
I&#39;m reading about synapsis and tetrads in Prophase I, and in the picture it has two sister chromatids, and I don&#39;t understand how there are 4 total chromosomes, so that when in Anaphase, splitting occurs in meiosis, each new cell has one chromosome from each homologous pair.