Aneuploid Types Research Articles

Hybrid progenies of the cross, Brassica campestirs*B. oleracea. IV. Crossability of F2, B1 and hybrid plants, and their progenies.

Crossability was examined in the F2, B1 and hybrid plants, and the somatic chromosomes of their progenies were investigated. The F2 and B1 plants were obtained in the self- and open pollinations, and in the F1 hybrids backcrossed to both parents, respectively. The hybrid plants were obtained in the cross between F1 hybrids and diploid Brassica oleracea, and between F1 hybrids and B. napus. All F1 hybrids were produced by ovary culture in vitro in the cross between B. campestris and B. oleracea, and between B. campestris and autotetraploid B. oleracea. The plants examined were classified into three types. The first type had 29 chromosomes in root tip cells, and the second had 38 chromosomes. The third type of plants was the plants having chromosomes other than 29 or 38 chromosomes. Many different types of aneuploids were obtained in open pollination of the F2, B1 and hybrid plants, in the progenies of the F2, B1 and hybrid plants crossed to B. campestris, and B. napus. It was suggested that the different types of normal egg cell with one by one or little by little chromosome addition might be produced, and that some specific chromosome or chromosome group might increase or decrease the crossability in aneuploid production. It might be considered that there were genes related to fertility. It might be possible that the genes of B. campestris and B. oleracea could exchange reciprocally. Further selection had to be done for the production of a new type crop of B. napus which had been reported in a previous paper.

Nuclear DNA Content, Histological Grade, and Clinical Course in Patients with Nonpalpable Mammographically Detected Breast Adenocarcinomas

Sixty-five consecutive female patients, age 35-83, with nonpalpable breast carcinomas detected by mammography were classified with both morphological and cytochemical malignancy grading. Cytochemically, the tumors were divided into euploid and aneuploid types indicating low and high malignancy potential, respectively. The mean follow-up time in the euploid group was 6.7 years and in the aneuploid group 8.0 years. No significant difference in mortality was observed in the two groups comprising 65% euploid and 35% aneuploid tumors. Our results here indicate that an early detection of breast cancer at a clinically occult and nonpalpable level leads to better prognosis even in patients with aneuploid tumors whose tumors otherwise are considered to be highly malignant.

Effects of High Dietary Fat on the Total DNA and Receptor Contents in Rats with 7,12-Dimethylbenz[a]anthracene-Induced Mammary Carcinoma

The influence of high dietary fat on the malignant intensity and the hormone receptors of 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary carcinoma in female Sprague-Dawley rats were analyzed by the tumor incidence and growth, the DNA histogram type, the DNA index, the S-phase fraction, and the estrogen receptor (ER) and progesterone receptor (PgR) assays. The rats were fed either a low-fat (0.5% corn oil) diet or a high-fat (20% corn oil) diet after the DMBA administration. Tumor incidences in the low-fat and the high-fat diet groups were 46 and 86%, respectively (p less than 0.01). Tumors in the high-fat diet group were also significantly larger than those in the low-fat group. Average tumor latent period was significantly shorter in the high-fat diet group, comparing with that in the low-fat diet group (p less than 0.01). Sixty-nine percent of the tumors in the high-fat diet group had aneuploid type, while only 8% of those in the low-fat diet group had aneuploid type. The DNA index and S-phase fraction also were significantly higher in the high-fat diet group (p less than 0.01). But the ER and PgR contents were not different between both groups. Therefore, these results suggest that a high dietary fat could increase the malignant intensity of the tumor but does not influence the hormonal responsiveness of these tumors.

Tests which distinguish induced crossing-over and aneuploidy from secondary segregation in Aspergillus treated with chloral hydrate or γ-rays

A system of tests with the ascomycete Aspergillus nidulans was devised that can detect 3 primary effects of genotoxic agents: (1) increases in mitotic crossing-over; (2) induced aneuploidy; and (3) clastogenic effects which cause chromosomal imbalance. Conidia of a new diploid tester strain, heterozygous for 4 recessive markers which alter conidial color, are treated and plated onto nonselective media. In cases of induced crossing-over, large color segments are found in normal green colonies, frequently adjacent to reciprocal twin segments. In contrast, both malsegregation and chromosome breakage produce unbalanced types which grow poorly and segregate further. Cases with yellow segregants are replated and their secondary diploid sectors tested for markers which are located on both chromosome arms in coupling with yA. Induced aneuploidy can be distinguished from chromosome breakage by the pattern of marker segregation. Any aneuploid type will produce euploid sectors solely by segregation of whole chromosomes; trisomic colonies ( yA/yA/+) will show 1:2 ratios for yellow (homozygous yA) to parental green ( yA/+) sectors and have characteristic phenotypes. Other induced unbalanced types, if heterozygous for deletions or aberrations, may produce yellow diploid sectors by secondary crossing-over as well as by nondisjunction and such cases show unique patterns of genetic segregation and non-predictable phenotypes. As a complementary test, haploid strains are treated, and induced abnormally growing types are replated and classified by phenotype. Aneuploids are unstable and produce many normal sectors, and some of these disomic or trisomic types can be visually identified. In contrast, induced deletions are lethal, and duplications or ‘morphological’ mutants show much more stable abnormal phenotypes. This test system was used to characterize the primary effects of γ-rays and chloral hydrate. Results and evidence were as follows: (1) A dose-dependent increase of color segments resulting from reciprocal crossing-over was found after treatment of dividing nuclei in germinating diploid conidia with γ-rays, but not with chloral hydrate. (2) Highly aneuploid and polyploid types were induced in diploid and haploid germinating conidia by chloral but not to any significant extent by γ-rays. (3) γ-Rays caused a dose-dependent increase of abnormally growing colonies when dormant or germinating diploid conidia were treated. These colonies produced secondary euploid sectors by spontaneous nondisjunction and frequently also by crossing-over, which provided evidence for induced semidominant and recessive lethal mutations of many types. γ-Irradiation of haploid conidia induced mainly abnormal colonies with stable or near-stable phenotypes (i.e., mutations and aberrations) and only very few unstable disomics were found.

Progression of mammary adenocarcinomas as reflected by nuclear DNA content.

In 18 breast cancer patients the DNA histograms observed in the primary tumor at the date of diagnosis were compared with those found in the corresponding local and distant metastases at autopsy up to more than 12 yr later. All patients, except one, exhibited the same type of DNA histogram in both the primary tumor and its metastases. In one patient the DNA histogram changed from an euploid type in the primary breast carcinoma to an aneuploid type in the metastases. The results are interpreted as indicating that mammary adenocarcinoma in general exhibit a high degree of stability of the nuclear DNA content during the history of the disease. It is suggested that in breast cancer progression of the tumor disease is more likely due to a net increase and/or dissemination of tumor cells exhibiting similar genetic properties and malignancy potential than to a progressive dedifferentiation and increase of malignancy of the tumor cells.

Disruptive effects of ethyl alcohol on mitotic chromosome segregation in diploid and haploid strains of Aspergillus nidulans

To identify, with certainty, the primary genotoxic effects of ethanol, condidia from diploid strains of Aspergillus nidulans were treated during early germination with ethyl alcohol, and all the resulting segregants from large samples were analysed in detail. Results were identical whether technical grade (95%), or highly purified ‘absolute’, alcohol was diluted to obtain the effective low levels of ethanol (3–6%). This makes it unlikely that trace contaminants, rather than ethanol itself, caused the observed induced segregation. At the most effective concentrations survival was about 50%, but over half of the colonies were abnormal and showed sectoring phenotypes. Higher concentrations were too inhibitory for growth. In practically all cases, when ‘abnormals’ were replated, aneuploids of various types were recovered. Most aneuploids were hyperdiploid, including a fraction of simple trisomics, and some were even polyploid types. All showed chromosomal-type segregation in diploid sectors, often segregating for genetic markers of many different chromosomes. Mitotic crossing-over was slightly increased, but probably not induced, since an equally high spontaneous frequency was observed among replated aneuploid types. To eliminate conclusively the possibility that chromosome breakage was the primary effect of ethanol, which might indirectly produce aneuploid-like types, haploid conidia were also treated. Up to 8% abnormals, mainly hyperhaploids, were obtained (at about 20–50% survival). When diploid and haploid strains were treated identically with ethanol in liquid media after a few hours of pregermination, frequencies of abnormals were similar for short treatments, but higher in diploid strains for longer ones (10–20% aneuploids). The abnormal colonies from the haploid strain were replated and visually identified: about 2 3 were typical n + 1 hyperhaploids, and most others were n + 2 or 3 or more, including a few 2 n + 1 trisomics. It is concluded that as a primary effect, alcohol interferes with, and probably arrests, mitotic segregation, and causes chromosome missegregation and nondisjunction. In most cases, the resulting nuclei contain increased numbers of chromosomes and show high frequencies of chromosome loss.

Ultrastructure of cell types cultured during preneoplasia from implant surfaces and foreign-body-reactive tissues in mice.

Cell types (I–IV), isolated and expanded in vitro from mouse foreign-body (FB)-reactive capsule tissue or from surfaces of FB segments, were sectioned en face and studied ultrastructurally. The macrophage-like and fibroblast-like nature of respectively, the euploid types I and II cells were substantiated by this ultrastructural study and thus confirmed earlier conclusions that were based on light microscopic morphology and in vitro growth characteristics. Particular emphasis was placed on the characterization and identification of type IV cells in that these aneuploid cells are sarcomagenic when implanted or injected sc into histocompatible recipient mice. The submicroscopic features of the aneuploid type IV cells included: 1) numerous microfilaments (diameter, 6–9 nm); 2) many plasmalemmal (pinocytotic) vesicles; 3) many surface microvilli, ruffles. or blebs; 4) formation of intercellular gap junctions; and 5) relatively extensive smooth-surfaced endoplasmic reticulum and significantly less rough-surfaced endoplasmic reticulum. The much smaller bipolar type III cells had several features in common with type IV cells: 1) an abundance of 6- to 9-nm (diameter) microfilaments, 2) moderate numbers of plasmalemmal vesicles, and 3) many evaginations of the plasma membrane to form microvilli or blebs. A relationship between types III and IV cells was considered likely on the basis of these morphologic similarities and other observations. The submicroscopic features of both types III and IV cells correlated closely with those present in FB-induced sarcoma cells. The specific in vitro characteristics of aneuploid type IV ceUs most closely resembled those of endothelial cells. The results of this study supported the hypothesis that the progenitor cells of FB-induced sarcomas were derived from primitive cells associated with the local microvasculature.

Somatic Hybridization by Fusion of Protoplasts : 1. The combination of Nicotiana tabacum and Nicotiana rustica

Mesophyll protoplasts of Nicotiana tabacum. cv. Bright Yellow mutant Aurea and Burley 21, and of N. rustica. cv. Rustica were prepared from leaf tissue by enzymatic digestion and were fused with the aid of polyethylene glycol. When the fused protoplasts were plated on an agar medium or in a liquid medium for cell culture, new cell walls were regenerated from them and the first cell division could be seen beginning on the 12th day of culture, and cell division process took place on and after the 21th day (Fig. 1). After one month culture, almost all of the surviving fused protoplasts grew to cell colonies of 1-2 mm in diameter. The cell colonies were subcultured on an agar medium for callus culture. On the medium, they grew vigorouly and formed calli of 2 cm in diameter after 2 months culture. At this stage, the hybrid calli showing greenish white with a compact appearance were selected in contrast to parental type calli tinged with white or green color (Fig. 2). Ten somatic hybrid calli of the combination of Aurea and Rustica and 3 calli of the combination of Burley 21 and Rustica were obtained. Many plantlets were differentiated from these calli when transfered to a medium enriching zeatin (Fig. 3). All of the mature flowering plants showed to be perfectly hybrid, and the shape of the leaves and flowers indicated an intermediate between N. tabacum and N. rustica (Fig. 5, 6). The plant height of the normal hybrid morphologically was higher than that of the parent plant and all of the hybrid plants were highly resistant to the tobacco mosaic virus (Fig. 4, Table 1, 2). The chromosome numbers of the somatic hybrids showed to be the aneuploid type having from 60 to 91 chromosomes (Table 1, 2). The normal hybrid plants morphologically, however, have a pollen fertility, and seeds and progenies were obtained from 4 of the Aurea-Rustica hybrids and 3 of the Burley 21-Rustica hybrids (Table 1, 2).

Location of chromosomal control of GA-induced enzyme release by distal half-grains of wheat.

The three enzymes, alpha-amylase, peroxidase, and acid phosphatase, are among those released by the aleurone of bread wheat, Triticum aestivum, as a direct response to gibberellins (GA) from the embryo during germination. Aneuploid genotypes are used to investigate the chromosomal location, nature, and extent of genetic control of the release of these enzymes in endosperms after induction by exogenous GA. Ditelosomics demonstrate the effect of removal of known chromosome arms, and tetrasomics show the effect of duplication of chromosome pairs. Quantitative analysis demonstrates complex control systems over and above those previously found using zymogram techniques. For alpha-amylase, chromosome arms with net promoter effects and chromosomes with net inhibitor effects were found. These effects were not chromosome-dosage responsive, unlike the promoter-inhibitor system found for acid phosphatase control. Peroxidase levels in the endosperms were generally high in both types of aneuploids. With one exception, all chromosomes showing involvement as ditelosomics showed a similar effect as tetrasomics, indicating that in the euploid a balanced state restricting, rather than promoting, peroxidase levels existed.

Mitotic crossing over and nondisjunction in translocation heterozygotes of Aspergillus.

To analyze mitotic recombination in translocation heterozygotes of A. nidulans two sets of well-marked diploids were constructed, homo- or heterozygous for the reciprocal translocations T1 (IL;VIIR) or T2 (IL;VIIR) and heterozygous for selective markers on IL. It was found that from all translocation heterozygotes some of the expected mitotic crossover types could be selected. Such crossovers are monosomic for one translocated segment and trisomic for the other and recovery depends on the relative viabilities of these unbalanced types. The obtained segregants show characteristically reduced growth rates and conidiation dependent on sizes and types of mono- and trisomic segments, and all spontaneously produce normal diploid sectors. Such secondary diploid types either arose in one step of compensating crossing over in the other involved arm, or--more conspicously--in two steps of non-disjunction via a trisomic intermediate.--In both of the analyzed translocations the segments translocated to IL were extremely long, while those translocatated from IL were relatively short. The break in I for T1 (I;VII) was located distal to the main selective marker in IL, while that of T2 (1;VIII) had been mapped proximal but closely linked to it. Therefore, as expected, the selected primary crossover from the two diploids with T2 (I;VIII) in coupling or in repulsion to the selective marker, showed the same chromosomal imbalance and poor growth. These could however be distinguished visually because they spontaneously produced different trisomic intermediates in the next step, in accordance with the different arrangement of the aneuploid segments. On the other hand, from diploids heterozygous for T1 (I;VII) mitotic crossovers could only be selected when the selective markers were in coupling with the translocation; these crossovers were relatively well-growing and produced frequent secondary segregants of the expected trisomic, 2n + VII, type. For both translocations it was impossible to recover the reciprocal crossover types (which would be trisomic for the distal segments of I and monosomic for most of groups VII or VIII) presumably because these were too inviable to form conidia.--In addition to the selected segregants of expected types a variety of unexpected ones were isolated. The conditions of selection used favour visual detection of aneuploid types, even if these produce only a few conidial heads and are not at a selective advantage. For T2 (I;VIII) these "non-selected" unbalanced segregants were mainly "reciprocal" crossovers of the same phenotype and imbalance as the selected ones. For T1 (I;VII) two quite different types were obtained, both possibly originating with loss of the small VII-I translocation chromosome. One was isolated when the selective marker in repulsion to T1 (I;VII) was used and, without being homo- or hemizygous for the selective marker, it produced stable sectors homozygous for this marker...

Aneuploidy in guava

Aneuploids have been identified cytomorphologically in progenies from triploid and diploid-triploid crosses. 30 trisomics, 2 double trisomics, 1 tetrasomic, and 2 higher aneuploids were obtained. Some of the aneuploids were found to be different from those reported earlier and higher aneuploids carried eight extra chromosomes. The plants with one extra chromosome occurred more frequently (67%) than the other aneuploid types. The changes in morphological traits such as a reduction in the amount of growth and the size of leaf etc. distinguished aneuploids from diploids. In the higher aneuploids the plant parts were highly exaggerated and pollen sterility was very high. The chromosomal counts in acetocarmine squashes confirmed the presence of extra chromosome(s). Aneuploids particularly trisomics were found to be promising and may lead to the production of commercially viable plants.

Prognosis of irradiated carcinoma of cervix uteri and nuclear DNA in cytologic postirradiation dysplasia.

The authors examined 222 cytologic specimens from 60 patients with squamous cell carcinoma of the cervix, International Stages II and III, who were treated with radiation at the University of Minnesota Hospitals between 1964 and 1967. When evidence of postirradiation dysplasia (PRD) was found, the nuclear DNA content of the dysplastic cells was measured by two-wavelength Feulgen micro-spectrophotometry, with 20 morphologically normal intermediate squamous cells used as controls. On the basis of these measurements, occurrences of PRD were classified as diploid, polyploid, or aneuploid. Types of PRD were correlated with 5-year rates of recurrence of disease. The incidence of PRD, especially of the aneuploid type, was significantly higher in women who died within 5 years. Six of seven women with cytologic evidence of the aneuploid type of PRD had recurrent disease within 2 years. The data suggest that micro-spectrophotometry of cytologic samples might contribute to early detection of recurrent malignant disease, especially in patients who show evidence of aneuploid postirradiation dysplasia.

REPRODUCTIVE ERRORS IN ANEUPLOIDS: GENERATION OF VARIANT EXTRA-CHROMOSOMAL TYPES BY TOMATO PRIMARY TRISOMICS

Primary trisomics of the tomato spawn an array of other primary trisomics as well as such modified types as secondary, tertiary, and telo-trisomics and primary tetrasomics. Five useful, previously undescribed trisomic types were thereby obtained. Although the frequency of deviant types is very low, they can be readily screened from the total population by their markedly differing phenotypes. It is therefore feasible to obtain specific desired types of aneuploids by systematically seeking them in progenies of the corresponding primary trisomic. The data suggest, although they are not sufficiently extensive to prove, that the deviating aneuploids tend to have shorter chromosomes of the tomato complement as their extra elements and tend to be more frequent in the progeny of trisomics for the shorter chromosomes. Cytological studies of triplo-5, the most prolific source of deviants, revealed a substantial frequency of laggards and chromosomes otherwise behaving abnormally at anaphase of both meiotic divisions, thus suggesting mechanisms to account for the origin of the deviant aneuploids.

The mosaic composition of the DNA content of the epidermal carcinomas of man.

The Deoxyribonucleic acid (DNA) content of various epidermal carcinomas recognized clinically as senile Keratosis, In Situ carcinomas, and squamous cell carcinomas, was measured microspectrophotometrically by the two wave length method of Patau. In addition, metaphase and interphase nuclei of a few healing ulcers were measured to serve as controls. The metaphase nuclei were preferred for these measurements mainly because of the lack of any interference due to DNA synthesis at this stage of the cell cycle. The DNA value of the cells in various cases of senile Keratosis always falls in the diploid range. The In Situ carcinomas show a variable degree of mosaic composition ranging from diploid to sixteen ploid, suggesting that there are several aneuploid cell types growing side by side in the same tumor bed. Squamous cell carcinomas, which are invariably invasive, in most cases belong to a hyper-diploid or hyper-tetraploid stem line. The data has been discussed with a view to determine the feasibility of using this technique as a routine method for clinical diagnosis.

Autosomal translocations causing male sterility and viable aneuploidy in the mouse.

In previous experiments on the induction of translocations in the mouse tests were usually confined to the sons of treated animals. In the present experiment daughters of irradiated males were studied, with a view to finding the frequency of X-linked translocations and of autosomal aberrations causing male sterility. The treated males were given 600 rad X-rays to the hind part of the body and offspring were obtained in the pre-sterile period. Forty-six of the 168 daughters studied were semi-sterile, and, of these, 26 carried translocations causing semi-sterility in both sexes, five carried translocations causing semi-sterility in females and full sterility in males and five had translocations giving some semi-sterile and some sterile males. All the translocations were autosomal. The five translocations causing male sterility were studied more fully. All gave chain quadrivalents and some univalents at male meiosis, and three out of four showed recognisably abnormal chromosomes at mitosis. An unexpected finding in two of the translocations was the occurrence of live adult mice with 41 or 39 chromosomes. The extra or absent chromosome was thought to be one of the translocation products. Two of the aneuploid types were associated with mild phenotypic abnormality, and in all cases the males were sterile and the females had reduced fertility. This is the first report of autosomal translocations causing male sterility and of inherited autosomal aneuploidy in the mouse.

THE ARTIFICIAL INDUCTION OF ANEUPLOIDS IN AVENA

The value of monosomic series in cytogenetic studies of polyploids has been well established for many years in species such as wheat (Triticum aestim~m L.) and tobacco (Nicotiann tnbacz~m L.). I t is reasonable to assume that equally valuable information would be obtained from such a series in common oats, Avenn sntivn L., which is hexaploid. Although this crop occupies the fourth place in total world production, relatively little cytogenetic investigation has been done. It is only recently that concerted efforts to produce a monosomic series have been made. The main problem at present is to find a suitable method or material from which to produce nlonosonlics. In wheat, most monosomics were obtained from a haploid pollinated with normal pollen and from a partially asynaptic nullisomic (Sears, 1954). Only one haploid has been reported thus far in hexaploid oats (Nishiyama, 1964, personal communication). Asynaptic nullisomics have been described by Huslcins (1927) who found the fatuoid conlplex to be associated with a specific chromosome deficiency. Unfortunately these nullisomics are sterile and thus cannot be used as a potential source of new monosomics. The majority of monosomics in A. sativa reported to date have been found by screening natural populations. Riley and Kimber (1961) reported 7 monosomics from 623 seedlings examined in the variety Sun 11. McGinnis (1962) analysed 4,023 seedlings from foundation lines of the variety Garry and found 2 nullison~ics, 17 monosomics and 5 trisomics. Recently Haclcer and Riley (1963) obtained 6 nullisomics, 40 monosomics and 4 trisomics from 3,453 seedlings of the variety Sun 11. Although l~igllly honlogeneous aneuploids are obtained from this method, the frequency of naturally occurring monosomics is low and the screening method is extremely long and tedious. Artificial induction of monoso~nics in A. sativn was attempted by CostaRodrigues (1954). By irradiating pre-flowering panicles of the variety Missouri 04047 at 300 r, he obtained 20 monosoinics out of 279 progeny analysed. Such a high frequency of n~onosoinics (7.2%) indicates that irradiation is an efficient method of inducing n~onosomics. O'Mara (1961) has suggested that because of the random action of irradiation, all 21 different monosomics could be produced by this method. McGinnis (unpublished) &radiated pre-flowering panicles of the variety Garry at 300 r and obtained 41 monosomics out of 506 progeny (8.1%). In addition 14 other aneuploid types were found, nine of which were potential monosomics. In view of the success realized by the earlier investigations, a project to determine the most efficient level of X-irradiation was conducted on the three levels of ploidy in Aue7zn. In addition the effectiveness of certain Icnown mutagenic chemicals and of high frequency sonic vibration in producing aneuploids in A. sntiun was studied.

Chromosome-mosaics Observed in a Variety of Wheat, “Shirahada”

1) A variety of wheat, “Shirahada”, showed an abnormal meiotic behavior, “chromosome-mosaics”. In every plant selected at random there were to be seen aneuploid PMC's such as “hypo-” or “hyper-” cells mixed together with euploid ones in the same anther-loculus. Especially the “hypo-” cells with less than 2n chromosome number were frequently noticed. Such aberrant PMC's are usually characterized by a relatively large number of unpaired chromosomes.2) In euploid PMC's there were often observed one or two pairs of univalents while multivalent chromosomes such as trivalent or tetravalent were rarely discovered. On an average about 18% of aneuploid PMC's observed had such irregularities. Laggards and bridges were also frequently observed in both 1st and 2nd anaphase, especially so in 1st division.3) An upset in mitosis which was induced by gene-controlled spindle abnormalities just before meiosis seems to be the probable cause of the origin of these hypo- and hyper-cells.4) As a result of such irregularities in the meiotic division, there appeared frequently in the progenies various types of aneuploids, especially monosomics (2n=41). In the self-pollinated progenies of a plant with the lowest seed fertility, a series of aneuploids having 2n=39, 40 and 41 chromosome numbers were found together with euploids (2n=42).

SEX DETERMINATION IN DIPLOID‐TRIPLOID CROSSES OF SPINACIA OLERACEA

Mahoney, D. L. Jules Janick, and E. C. Stevenson. (Purdue U., Lafayette, Ind.) Sex determination in diploid‐triploid crosses of Spinacia oleracea. Amer. Jour. Bot. 46(5): 372–375. 1959.—Segregation for sex in spinach was studied in a series of diploid pistillate × triploid staminate crosses. The genetic data indicated that the functional gametes from staminate triploids were not confined to n and n + 1 types. Cytological analyses of progenies from a number of 2n ♀ × 3n (XYY and XYY) ♂ crosses revealed similar but non‐homogeneous types of chromosome segregation. These crosses produced 49.3% diploids, 17.9% trisomies, 0.5% with 14 chromosomes, 1.2% with 16 chromosomes, 11.4% with 17 chromosomes, 18.9% triploids, and 0.8% with 19 chromosomes. The reciprocal crosses produced a higher percentage of aneuploid types including 1.7% with 15 chromosomes. Segregation for sex in each of the various chromosome numbered progeny of diploid‐triploid crosses was presented and analyzed.