Robertsonian chromosomes and the nuclear architecture of mouse meiotic prophase spermatocytes

Biological Research

Table 2 Combination of associated and single metacentric/telocentric bivalents per nucleus observed in 2n = 24 spermatocytes

Combinations between 8 metacentric bivalents	Combinations between 3 telocentric bivalents	Metacentric/Telocentric associations	Number of spermatocytes per nuclear combination	% of spermatocytes per Class
8-0	- - -		0	0
7-1	2(3); 5(2-1)		7	7
6-2	3(3); 2(2-1)		5	12
6-1-1	2(3); 5(2-1)	1(1M2T)	7	12
5-3	1(1-1-1)	1(3M1T)	1	8
5-2-1	1(3); 3(2-1)		4
5-1-1-1	2(3);1(1-1-1)		3
4-4	1(2-1);2(1-1-1)		3	31
4-3-1	3(3); 9(2-1); 1(1-1-1)		13
4-2-2	2(3); 3(2-1); 1(1-1-1)	1(2M2T)	6
4-2-1-1	2(3); 4(2-1); 2(1-1-1)	1(1M1T)	8
4-1-1-1-1	1(1-1-1)		1
3-3-2	1(3); 4(2-1); 2(1-1-1)	1(1M1T)	7	38
3-3-1-1	3(3); 4(2-1); 3(1-1-1)	1(3M1T)	10
3-2-2-1	4(3); 8(2-1); 2(1-1-1)	1(1M1T)	14
3-2-1-1-1	1(3); 4(2-1);	1(1M1T)	5
3-1-1-1-1-1	2(2-1)	1(3M1T) 1(1M1T)	2
2-2-2-2				4
2-2-2-1-1	1(3): 2(2-1);1(1-1-1)	1(2M2T);1(1M1T)	4
2-2-1-1-1-1
2-2-1-1-1-1
2-1-1-1-1-1-1
1-1-1-1-1-1-1-1				0
TOTAL	27(3); 56(2-1); 17(1-1-1)	12	100	100

100 nuclear microspreadings from 2n = 24 spermatocytes were examined.The SC and the pericentromeric heterochromatin were identified by immunochemistry using, respectively, anti-SYCP3 and anti-H3K9me3 antibodies (as in Figure 4c & d).
The first column shows the combination of associated and single metacentric bivalents per nucleus; The 2^nd column the combination of associated and single between 3 telocentric bivalents; the 3th column the spermatocytes that showed associations between metacentric and telocentric bivalents; The 4^th column the frequency of spermatocytes per nuclear combination; and the 5^th column the frequency of spermatocytes per Class, considering as such, all the nuclei sharing the same highest combination of metacentric bivalent.
For example the third line of this Table means: In 5 spermatocytes the metacentrics were in a group of 6 and in another of two bivalents. In 3 of these spermatocytes the telocentrics were all together and in 2 they were in a combination 2 together and one alone. 12 spermatocytes were Class 6 or 12 had 6 as the higher number of associated metacentric bivalents.

ISSN: 0717-6287