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.
By two years of age, about 40,000 new synapses are being formed every second, and during early childhood the total number of synapses is much higher than the number of synapses in the average adult brainâabout a quadrillion (1,000,000,000,000,000) synapses, which is about 150,000 times the Earthâs population.