Fig. 2

Histological observation of zebrafish (Danio rerio) androgenetic-induced eggs from 5 to 43 min after fertilization (AF).

(a–d) androgenetic haploid type; (e–h) triploid type; and (i–l) diploid or aneuploid type. (a) 5 min AF, the spindle was destroyed by cold-shock treatment, and part of the blastodisc swelled up with all the chromosomes; (b) 30 min AF, the blastodisc swelled further with all the chromosomes; (c) 35 min AF, the swelled blastodisc released as second polar body with all chromosomes; (d) 43 min AF, only one pronucleus was observed in the egg; (e) 5 min AF, part of the blastodisc swelled; (f) 30 min AF, the blastodisc swelled further with no chromosomes; (g) 35 min AF, few parts of the blastodisc were released, and all chromosomes remained in the egg; (h) 43 min AF, the zygote was formed by the fusing of female and male pronuclei; (i) 5 min AF, the unswelled blastodisc; (j) 15 min AF, parts of the blastodisc swelled up with some chromosomes, and other chromosomes were found at unswelled parts of the blastodisc; (k) 35 min AF, the second polar body was released with some chromosomes, and the unreleased chromosomes in the egg developed into the female pronucleus; (l) 43 min AF, the female pronucleus became bigger. Scale bars denote 10 µm. Abbreviation: 2PB, 2nd polar body; 2MeC, 2nd meiotic chromosomes; FN, female nucleus; FPN, female pronucleus; MPN, male pronucleus; ZY, zygote.