2. Χ Υ

3. B.

7. Η ανάπτυξη των γονάδων στο ανθρώπινο έμβρυο αρχίζει την 32η ημέρα της κύησης. Δημιουργούνται οι γοναδικές ακρολοφίες στην κοιλιακή επιφάνεια του κρανιακού μεσόνεφρου, που προέρχεται από το διάμεσο μεσόδερμα.

8. Table 2. Factors involved in early gonadal ridge development. Gene Chromosomal localization Expression Function References LHX1 (LIM homeobox gene 1) 11p12-p13 Primitive streak, prechordal and intermediate mesoderm, brain, thymus, tonsil Differentiation and development of the head, neural and lymphoid tissues and urogenital structures 3, 288 LHX9 (LIM homeobox gene 9) 1q31-q32 Central nervous system, forelimb and hind limb mesenchyme and urogenital system Activation of SF-1 in gonadal primordia 6, 7 19 EMX2 (homolog of empty spiracles homeobox gene 2) 10q26.1 Telencephalon and epithelial components of the urogenital system Arealization of the neocortex and induction of the mesenchyme 4, 289 PAX2 (Paired box gene 2) 10q24.3-q25.1 Mesonephros, metanephros, adrenals, spinal cord, hindbrain and optic and otic vesicles Regulation of WT1 expression and of mesenchyme- to- epithelium transition 5, 290, 291 M33 (CBX2) (Chromobox homolog gene 2) 17q25 Unknown Regulation of homeotic genes 8, 9 WT1 (Wilms tumor associated gene 1) 11p13 Urogenital ridge derivatives DNA- and RNA- binding protein with transcriptional and post-transcriptional regulating capacity 10, 11 SF-1 (Steroidogenic factor 1) 9q33 Gonadal ridges, adrenal gland primordia, hypothalamus and pituitary Transcriptional regulation of STAR, steroid hydroxylases, gonadotropins, aromatase, AMH and DAX-1, and stabilization of intermediate mesoderm 16, 176, 292

9. 4 weeks5 weeks

17. Table 3. Growth factors in sex differentiation of the reproductive tract Growth factors Function in urogenital development HOXA13 Deletion in mice leads to limb defects, vaginal hypoplasia and deficiency of the os penis (Hypodactyly syndrome) (160) Human mutation produces limb and uterine abnormalities and urinary tract malformations (Hand-Foot-Genital syndrome ) (266) HOXD13 Male accessory organ morphogenesis (267) HOX10 Male accessory organ morphogenesis (268) TGF-ί Opposes action of androgen on prostatic cells (262) BMP4 Prostate differentiation (263) BMP7 and 8 Integrity of epididymis (264) FGF8 and 10 Growth of genital tubercle (161) SHH Development of external genitalia (156) Prostate development (260) Penile morphogenesis (261) WNT4 Growth of Mόllerian ducts (72) WNT7a Uterine patterning (285) Sex-specific development of Mόllerian ducts (185) Repression of Leydig cells in ovary (185)

33. The 'Guevedoces' of the Dominican Republic.

37. Sex chromosomes and Brain Sexual Differentiation XX and XY cells harvested from the midbrain of rat embryos develop different number of dopamine neurons. XY cultures contained more dopamine neurons than XX cultures, regardless of the gonadal type found in the embryo. In the lateral septum, XY males had a higher (more masculine) density of vasopressin fibers than XXSry males, and XY-Sry females were more masculine than XX females.

38. Female-enhanced gene expression in brains at 10.5 dpc

40. Male-enhanced gene expression in brains at 10.5 dpc