page_title: Development of the urinary system
section_title: Müllerian duct
hierarchical_section_title: Development of the urinary system / Müllerian duct
caption_attribution_description: Diagrams to show the development of male and female generative organs from a common type. (Allen Thomson.)
context_page_description: The development of the urinary system begins during prenatal development, and relates to the development of the urogenital system – both the organs of the urinary system and the sex organs of the reproductive system. The development continues as a part of sexual differentiation.
  The urinary and reproductive organs are developed from the intermediate mesoderm. The permanent organs of the adult are preceded by a set of structures which are purely embryonic, and which with the exception of the ducts disappear almost entirely before birth. These embryonic structures are on either side; the pronephros, the mesonephros and the metanephros of the kidney, and the Wolffian and Müllerian ducts of the sex organ. The pronephros disappears very early; the structural elements of the mesonephros mostly degenerate, but the gonad is developed in their place, with which the Wolffian duct remains as the duct in males, and the Müllerian as that of the female. Some of the tubules of the mesonephros form part of the permanent kidney.
context_section_description: Shortly after the formation of the Wolffian ducts a second pair of ducts is developed; these are the Müllerian ducts. Each arises on the lateral aspect of the corresponding Wolffian duct as a tubular invagination of the cells lining the abdominal cavity. The orifice of the invagination remains open, and undergoes enlargement and modification to form the abdominal ostium of the fallopian tube. The ducts pass backward lateral to the Wolffian ducts, but toward the posterior end of the embryo they cross to the medial side of these ducts, and thus come to lie side by side between and behind the latter—the four ducts forming what is termed the common genital cord, to distinguish it from the genital cords of the germinal epithelium seen later in this article. The Müllerian ducts end in an epithelial elevation, the Müllerian eminence, on the ventral part of the cloaca between the orifices of the Wolffian ducts. At a later stage the eminence opens in the middle, connecting the Müllerian ducts with the cloaca.
caption: A.—Diagram of the primitive urogenital organs in the embryo previous to sexual distinction. The common genital cord is labeled with gc. 
  * 3. Ureter.  
  * 4. Urinary bladder.  
  * 5. Urachus.  
  * cl. Cloaca.  
  * cp. Elevation which becomes clitoris or penis.  
  * i. Lower part of the intestine.  
  * ls. Fold of integument from which the labia majora or scrotum are formed.  
  * m, m. Right and left Müllerian ducts uniting together and running with the Wolffian ducts in gc, the common genital cord.  
  * ot. The gonadal ridge from which either the ovary or testis is formed.  
  * ug. Sinus urogenitalis.  
  * W. Left Wolffian body.  
  * w, w. Right and left Wolffian ducts.
exif: {}