| sex cell | A spermatozoon or an ovum. Synonym: germ cell. (05 Mar 2000) |
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| sex characteristics | Those characteristics that distinguish one sex from the other. The primary sex characteristics are the ovaries and testes and their related hormones. Secondary sex characteristics are those which are masculine or feminine but not directly related to reproduction. (12 Dec 1998) |
| sex chromatin | Condensed chromatin of the inactivated X chromosome in female mammals (Barr body). (18 Nov 1997) |
| sex chromosome | <genetics> Chromosome that determines the sex of an animal. In humans, where the two sex chromosomes (X and Y) are dissimilar, the female has two X chromosomes and the male is heterogametic (XY). <zoology> In birds, the opposite is the case, the male being XX and the female XY, in many organisms, there is only one sex chromosome and one sex is XX, the other X0. A portion of the X and Y chromosomes is similar and is known as the pseudoautosomal region. (14 Oct 1997) |
| sex chromosome imbalance | Any abnormal pattern of sex chromosomes; e.g., XXY in men with seminiferous tubule dysgenesis, XO in women with Turner's syndrome; rarer patterns of imbalance are XXX, XXXY, and XYY. See: isochromosome. (05 Mar 2000) |
| sex chromosomes | The homologous chromosomes that are dissimilar in the heterogametic sex. There are the x chromosome, the y chromosome, and the w, z chromosomes (in animals in which the female is the heterogametic sex (the silkworm moth bombyx mori, for example). In such cases the w chromosome is the female-determining and the male is zz. (12 Dec 1998) |
| sex cords | The gonadal cord's of the embryonic ovary or testis. Synonym: sex cords. (05 Mar 2000) |
| sex cord-stromal tumour | A malignant neoplasm of the ovary or testis. These tumours differentiate toward sex cords (in embryonic gonads) in the form of female (i.e., granulosa and theca) cells, male (i.e., sertoli and leydig) cells, or indifferent elements. In the ovary, sex cord-stromal tumours comprise 5% of all ovarian neoplasms. In the testes, leydig and sertoli cell tumours comprise about 5% of all testicular neoplasms, 10% of which behave in a malignant fashion. (12 Dec 1998) |
| sex counseling | Advice and support given to individuals to help them understand and resolve their sexual adjustment problems. It excludes treatment for psychosexual disorders or psychosexual dysfunction. (12 Dec 1998) |
| sex determination | Determination of the sex of a foetus in utero by identification of foetal chromosomes. (05 Mar 2000) |
| sex determination (analysis) | Validation of the sex of an individual by inspection of the gonads and/or by genetic tests. (12 Dec 1998) |
| sex determination (genetics) | Process in a given organism, by which the sex genotype is fixed. In humans, sex is established at the time of fertilization by the presence or absence of the y chromosome. (12 Dec 1998) |
| sex differentiation | Differentiation of male and female tissues and organs during embryogenesis, but after sex determination (sex determination (genetic)). (12 Dec 1998) |
| sex differentiation disorders | Disorders in the differentiation process of gonadal tissues and organs during embryogenesis. (12 Dec 1998) |
| sex disorders | Disturbances in normal sexual performance. (12 Dec 1998) |