A technique for chromosomal preparations from low yields harvest is presented using Poly-L-Lysine (300,000-400,000 MW). The procedure can be successfully used for peripheral blood lymphocytes, amniotic cell cultures, skin fibroblasts, direct preparations from bone marrow, cloned clusters and colonies from bone marrow grown on agar or methyl cellulose and eggs and blastocysts, with applications to other tissues. The technique is simple with minimal cell loss, and chromosomal preparations of good quality can be obtained which are amenable to all banding techniques.
A 29-year-old infertile man with mild eunuchoid body proportions and unilateral gynecomastia with a low sperm count had normal chromosomes in lymphocytes and skin fibroblasts. Serum testosterone, urinary ketosteroid, and follicle-stimulating hormone levels were normal, but serum prolactin, luteinizing hormone, and estrogen levels were above normal. Testicular biopsy showed hypocellularity, a pacuity of maturing sperm, and increased lipid content in early spermatogonia. Cytogenetic analysis of the testicular material showed probable 46,XY/47,XXY mosaicism in spermatogonial cells. None of the cells in diakinesis and metaphase I showed the extra-X as a univalent, and 50% of the cells in diakinesis were hypodiploid with intact XY bivalents. Further analysis of spermatogenesis revealed polymorphic dyads, triads, tetrads, and uncleaved meiotic products of first and second meiosis. Sex chromatin studies of testicular cells showed that 20% of the cells were X-chromatin positive. Scanning electron microscopic study of sperm revealed a wide range of polymorphisms, with some uncleaved meiotic products maturing into double-headed and double-tailed sperm or sperm with bulbous middle pieces or protrusions. A cytogenetic basis for the origin of these abnormalities is presented.
Monosomy 21, whether homogeneous or as a mosaicism, is very uncommon. We report here a 3-month-old white female with a low degree of monosomy 21 in the blood karyotype (6.5%, 110 cells counted) but not in the skin fibroblasts, which contained only the normal chromosome complement. The patient's physical features included microcephaly with frontal slanting; prominent occiput; ridge-shaped sutures; agenesis of the corpus callosum; large, prominent ears; high and narrow palate; micrognathia; tetralogy of Fallot; crowded toes; and dry, thick skin with very little subcutaneous tissue. The case is discussed in light of the suggested clinical features of the "monosomy 21" syndrome and the possible implications of such a low-grade mosaicism in prenatal diagnosis.
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