Polymerase chain reaction (PCR) assessment of clonal immunoglobulin (Ig) and T-cell receptor (TCR) gene rearrangements is an important diagnostic tool in mature B-cell neoplasms. However, lack of standardized PCR protocols resulting in a high level of false negativity has hampered comparability of data in previous clonality studies. In order to address these problems, 22 European laboratories investigated the Ig/TCR rearrangement patterns as well as t(14;18) and t(11;14) translocations of 369 B-cell malignancies belonging to five WHO-defined entities using the standardized BIOMED-2 multiplex PCR tubes accompanied by international pathology panel review. B-cell clonality was detected by combined use of the IGH and IGK multiplex PCR assays in all 260 definitive cases of B-cell chronic lymphocytic leukemia (n ¼ 56), mantle cell lymphoma (n ¼ 54), marginal zone lymphoma (n ¼ 41) and follicular lymphoma (n ¼ 109). Two of 109 cases of diffuse large B-cell lymphoma showed no detectable clonal marker. The use of these techniques to assign cell lineage should be treated with caution as additional clonal TCR gene rearrangements were frequently detected in all disease categories. Our study indicates that the BIOMED-2 multiplex PCR assays provide a powerful strategy for clonality assessment in B-cell malignancies resulting in high Ig clonality detection rates particularly when IGH and IGK strategies are combined.

A comparison has been made between gonocytes and adult type undifferentiated spermatogonia in the mouse. The following morphological resemblances were noted: 1. Proliferating gonocytes, at days 13 and 14 p.c., resemble proliferating undifferentiated spermatogonia between stages IX and IV in the adult. 2. Gonocytes in G1 arrest, from day 15 p.c. until birth, resemble undifferentiated spermatogonia in G1 arrest from stage IV until stage VIII. Both populations of cells undergo the same morphological changes during this period, known to accompany transformation of most Aal spermatogonia into A1 spermatogonia in the adult. 3. Gonocytes in late G2 or prophase, 24 h p.p., resemble A1 spermatogonia in late G2 and prophase in stage IX. 4. Most of the daughter cells of the gonocytes resemble A2 spermatogonia, the others resembling adult undifferentiated spermatogonia. The hypothesis is put forward that gonocytes are identical to adult type undifferentiated spermatogonia. The primordial germ cells then give rise to adult type spermatogonial stem cells (As).

The first appearance of spermatogenic cell types related to the age of the animal was studied in sections and tubular whole mounts of testes of normal mice (Cpb-N strain) up to 34 days pp. The first intermediate spermatogonia and leptotene spermatocytes were seen at days 4 and 7 p.p., respectively. It was found that the subsequent types of spermatogenic cells appear earlier than could be expected if spermatogenesis was to proceed at adult speed. [3H]thymidine labelling studies revealed that within a given interval of time, spermatocytes and spermatids in immature mice develop into more advanced cell types than in adults. The labelling studies and the observation that the cellular associations are always identical to those in the adult, indicate that the rate of acceleration in young mice is the same for spermatogonia, spermatocytes and spermatids. The mean duration of the cycle of the seminiferous epithelium during the age interval of 10 to 30 days p.p. is 7.51 +/- 0.10 days, compared to 8.61 +/- 0.08 in the adult. It increases gradually towards the adult level, reaching the value of 8.45 +/- 0.17 days between days 33 and 56 p.p.

Spermatogonial proliferation was studied in mice from day 13 p.p. when the seminiferous epithelium is incomplete, until week 12 p.p. when a steady state at adult levels has been attained. Counts of undifferentiated, A1 and intermediate spermatogonia and primary spermatocytes in stages IV and IX of the cycle of the seminiferous epithelium were made in whole mounted seminiferous tubules. Sertoli cell proliferation was studied in a separate series from 6 to 14 days p.p. employing the 3H-thymidine labeling index. It appeared that 1. Sertoli cell proliferation stops at day 12 whereafter the cells obtain their adult appearance; 2. The numbers of stem cell spermatogonia and the production of differentiating A1 spermatogonia increase almost twofold between day 13 and week 12; 3. The efficiency of the divisions of the differentiating A1-B spermatogonia is similar to that in the adult throughout this period; 4. At all ages studied, the cell counts revealed an almost constant numerical relationship between Sertoli cells and germ cells, which suggests a function of Sertoli cells in the regulation of spermatogonial proliferation.

Flow cytometric DNA-ploidy measurements were performed on paraffin-embedded and fresh tumor specimens from 690 patients with Stage I-III breast cancer. The conventional classification of DNA-ploidy (diploid versus aneuploid) was compared with a division of tumor ploidy into 5 classes based on DNA index (DI) range. The DI-classification showed a better correlation with tumor size and TNM stage than the conventional classification. Aneuploidy was associated with an impaired survival and distant relapse-free survival (p = 0.02) but the DI-classification improved the discrimination between different prognostic groups of patients. In general, this indicated a more aggressive phenotype for tumors evolved via polyploidization. Hyper-tetraploidy (DI greater than 2.10) indicated a very poor prognosis in pre-menopausal patients. No prognostic effect of aneuploidy and DI-class was found in node-negative and TI patients. Cox multivariate regression analysis showed that aneuploidy was an additional prognostic factor to nodal status (I less than or equal to N less than or equal to 3, N greater than 3 vs. N = 0) and tumor size (T2-4 vs. TI) for overall and distant relapse-free survival. Subdivision according to DI-class did not improve the prognostic power of DNA-ploidy due to stronger correlations with established prognostic factors.