Spider spinnerets evolved from leg homologs

Female Parasteatoda tepidariorum spiders collected from the wild were placed in a laboratory incubator for artificial feeding, observed and collected the laying of eggs.The oocysts at 8.2, 9.2 and 10.1 developmental stages were selected, the surface of the messy oocysts was peeled off with tweezers, and the eggs were placed in a 1.5 ml centrifuge tube, frozen with dry ice for 10 minutes, and sent to a biological company for sequencing. About 20 eggs were retained for formaldehyde fixation at each sample delivery to facilitate identification of embryonic development period. After fixation, the eggs were stored in a -20 degrees Celsius refrigerator.