Chromatin patterns in fishes with emphasis on sexual dimorphism

Twelve species of fish were investigated to determine whether sexual dimorphism occurs in the nuclei of their tissues as has been described for mammals. Feulgen-positive masses were present in nuclei of most tissues; some were similar in size, shape, and location to sex chromatin found in human buccal smears of the female. Although in Salmo gairdneri (rainbow trout) incidences of intranuclear chromatin masses in tissues of males were significantly higher than those of females, it was impossible to detect microscopically a nuclear sex difference in any of the species examined.

Skeletal malformations in the Holtzman rat embryo following the administration of thalidomide

Since the occurrence of the thalidomide tragedy in man, fairly extensive animal research has been done on the rat (King & Kendrick, 1962; Bignami et al., 1962; Klein Obbink &Dalderup, 1963; McColl et al., 1963; Moore et al., 1964), mouse (Giroud et al., 1962; Woollam, 1962; DiPaolo, 1963), rabbit (Felisati, 1962; Somers, 1962; Spencer, 1962), monkey (Lucey &Behrman, 1963), chicken (Kemper, 1962; Yang et al., 1963; Rickenbacher, 1964) and Drosophila (Lüers, 1962; Parkash, 1962).

There are, however, only a few instances where fetal deformities have resulted from the administration of thalidomide to rats. King & Kendrick (1962) gave thalidomide orally and intraperitoneally to Sprague-Dawley rats in doses ranging from 10 to 50 mg. and observed the following gross malformations in 6·9 per cent, of the fetuses: hamartoma of the palate with accessory incisors, malrotation of the hind limbs and absence of the tail.

Human Chromosomes: II. Preparation, Analysis and Diagnostic Implications of Abnormalities

This presentation is designed to show the diagnostic implications of chromosomal abnormalities, and how in some cases chromosome analysis may be helpful in prognosis and counselling. Most males with Klinefelter's syndrome have chromatinpositive nuclei and an abnormal sex chromosome complex (usually XXY). In Turner's syndrome many such females have chromatin-negative nuclei and a deficient sex chromosome complex (usually XO). Multiple-X females have unusual chromatin patterns (two or three masses of sex chromatin) and abnormal sex chromosome complexes (XXX, XXXX, XO/XXX, etc.). One of the parents of a translocation mongol may carry a translocation chromosome and pass it to future children. Cytogenetic data are therefore essential for genetic counselling. Mosaic and deletion mongols may show incomplete manifestations of mongolism, which make diagnosis difficult; chromosome analysis is helpful in diagnosis, and in prognosis concerning mental development. Abnormal chromosome numbers result from non-disjunction, usually during gametogenesis. The error may occur, however, during cleavage, producing cells with different chromosome complements (mosaicism). Visible structural abnormalities of chromosomes result from deletions or translocations of chromosome fragments.

Human Chromosomes: I. Preparation, Analysis and Diagnostic Implications of Abnormalities

This presentation is designed to help persons unfamiliar with cytogenetic terms and techniques to understand how chromosomes are prepared and analyzed to determine if abnormalities exist. A diagrammatic flow-sheet has been used to show how peripheral blood is treated to stimulate growth of cells, and how chromosomes are dispersed and made readily visible. Technical details have been replaced by simple statements explaining the various steps. By careful attention to differences (over-all length, position of centromere, length of arms, presence or absence of satellites), chromosomes may be arranged in order of length and into definite groups to form a typical karyotype of a person's cells. Familiarity with chromosomes makes it possible to determine (a) if an extra chromosome is present, (b) if a chromosome is missing, or (c) if an abnormal chromosome exists.