{"id":1354,"date":"2020-08-06T22:26:06","date_gmt":"2020-08-06T22:26:06","guid":{"rendered":"https:\/\/meddists.com\/learn\/pre-clinical\/medical-genetics\/cytogenetics\/"},"modified":"2021-02-06T12:08:13","modified_gmt":"2021-02-06T11:08:13","slug":"cytogenetics","status":"publish","type":"page","link":"https:\/\/meddists.com\/learn\/pre-clinical\/medical-genetics\/cytogenetics\/","title":{"rendered":"Cytogenetics"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\"><div class=\"intro\">Cytogenetics is a sub-field of genetics dealing with the behavior of cells based on their chromosomes.<\/div><\/p>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n<span class=\"block-heading\" id=\"header_1\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Description<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_1\">\n\n\n<p class=\"wp-block-paragraph\">A <strong>sex-determination system<\/strong> is a biological system that determines the development of sexual characteristics in an organism. It occursin three different stages or types. All 3 of them happen before the fetus is born.<\/p>\n\n\n<\/span><span class=\"block-heading\" id=\"header_2\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Types of sex determination<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_2\">\n\n\n<p class=\"wp-block-paragraph\">There are three types of sex determination:<\/p>\n\n\n\n<ol class=\"wp-block-list\"><li>Chromosomal or Genetic sex<\/li><li>Gonadal sex<\/li><li>Phenotypic sex<\/li><\/ol>\n\n\n<\/span><span class=\"block-heading\" id=\"header_3\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Chromosomal sex<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_3\">\n\n\n<p class=\"wp-block-paragraph\">Determined at fertilization and depends on which sperm fertilized the egg. Under normal circumstances, the chromosomal sex can be XX for females or XY for males.<\/p>\n\n\n\n<div class=\"wp-block-image\"><figure class=\"aligncenter\"><a href=\"https:\/\/meddists.com\/wp-content\/uploads\/2020\/01\/765px-Human_male_karyotpe_high_resolution.jpg\" target=\"_blank\" title=\"Cytogenetics\"><img decoding=\"async\" src=\"https:\/\/meddists.com\/wp-content\/uploads\/2020\/01\/765px-Human_male_karyotpe_high_resolution.jpg\" alt=\"\" class=\"wp-image-23343\"\/><\/a><figcaption><strong>Karyotype of a normal, human, male<\/strong> (Credit; National Human Genome Research Institute)<\/figcaption><\/figure><\/div>\n\n\n<\/span><span class=\"block-heading\" id=\"header_4\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Gonadal sex<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_4\">\n\n\n<p class=\"wp-block-paragraph\">Determines the formation of the testes (for males) or ovaries (for females). The embryo before 7 weeks, has 2 duct systems irrespective of chromosomal sex; Wolffian duct (male) and Mullerian duct (female). The presence of Testis Determining Factor (TDF) on the Sex determining region of Y (SRY) gene on the Y chromosome causes the Wolffian duct to develop as the testis and the Mullerian to degenerate. The testes will produce testosterone. In females, no Y chromosome, no TDF, no SRY, and the Wolffian duct degenerates. The Mullerian duct forms the oviduct, uterus, and part of the vagina.<\/p>\n\n\n<\/span><span class=\"block-heading\" id=\"header_5\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Phenotypic sex&nbsp;<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_5\">\n\n\n<p class=\"wp-block-paragraph\">Determines the formation of the penis or outer part of the vagina. It is influenced by the hormones produced by the gonads. The presence of testosterone in males promotes the development of the penis while the absence of testosterone in females promotes the formation of the clitoris and the vagina.<\/p>\n\n\n<\/span><span class=\"block-heading\" id=\"header_6\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Regulation of sex determination<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_6\">\n\n\n<p class=\"wp-block-paragraph\">Sex determination is mainly regulated by the TDF on the SRY gene of the Y chromosome. Every embryo has 2 duct systems that can form the male or female reproductive system but the presence or absence of the SRY gene determines if it will become a male or a female. <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The default system development is that of a female but in the presence of the SRY gene, this is blocked and the male system is produced instead. But in the absence of the SRY gene, the female system, which is the default system, will develop<\/p>\n\n\n<\/span><span class=\"block-heading\" id=\"header_7\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Pathologies of sex determination<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_7\">\n\n\n<p class=\"wp-block-paragraph\">There are times when things can go wrong with one or more of the three stages of sex determination. These problems can lead to one of the following conditions:<\/p>\n\n\n\n<ol class=\"wp-block-list\"><li><strong>Hermaphroditism:<\/strong> A condition in which a person has both types of chromosomal sex i.e 46, XX and 46, XY. It can be caused by chimerism (when an organism is made from 2 different types of cells from 2 different cell lines) or hormonal disturbances.<\/li><li><strong>Pseudohermaphroditism:<\/strong> A condition in which the chromosomal sex and the gonadal sex match with each other but they do not match with the phenotypic sex e.g 46, XX (chromosomal sex) with ovaries(gonadal sex) but with male outer genitals(phenotypic sex) or 46, XY (chromosomal sex) with testis(gonadal sex) but with female outer genitals(phenotypic sex). The latter case is also known as Androgen Insensitivity Syndrome.<\/li><li><strong>Androgen insensitivity syndrome:<\/strong> As the name suggests, this is when the body cells cannot recognize the hormone testosterone. This means that testosterone is produced by the testes but it cannot act on the cells to causes any changes. Hence, body developments that require testosterone such as the development of male outer genitals, secondary sexual characteristics for men, etc will not develop. Hence, the outer genitals will develop into a vagina and the person will have female sexual behaviour.<\/li><\/ol>\n<\/span><div id=\"the_titles\" style=\"display:none;\"><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Description<\/h4><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Types of sex determination<\/h3><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Chromosomal sex<\/h4><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Gonadal sex<\/h4><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Phenotypic sex&nbsp;<\/h4><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Regulation of sex determination<\/h3><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Pathologies of sex determination<\/h3><\/div>","protected":false},"excerpt":{"rendered":"<p>Description A sex-determination system is a biological system that determines the development of sexual characteristics in an organism. It occursin three different stages or types. All 3 of them happen before the fetus is born. Types of sex determination There are three types of sex determination: Chromosomal or Genetic sex Gonadal sex Phenotypic sex Chromosomal [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":1343,"menu_order":1,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-1354","page","type-page","status-publish","hentry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.0 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Cytogenetics &#8211; Meddists<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/meddists.com\/learn\/pre-clinical\/medical-genetics\/cytogenetics\/\" \/>\n<meta name=\"twitter:label1\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data1\" content=\"3 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/pre-clinical\\\/medical-genetics\\\/cytogenetics\\\/\",\"url\":\"https:\\\/\\\/meddists.com\\\/learn\\\/pre-clinical\\\/medical-genetics\\\/cytogenetics\\\/\",\"name\":\"Cytogenetics &#8211; 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