Mesonephros

As primitive kidney ( mesonephros, " Wolffian body " ) is called the second generation in the kidney development in vertebrates. Their formation takes place in the embryo with the regression of pronephros ( pronephros ). While the primitive kidney in fish and amphibians also in adult animals is a place for education of the urine, the mesonephros forms in amniotes (animals with an amnion, ie reptiles, birds and mammals) the embryo back and is a third kidney generation, the metanephros ( metanephros, the actual kidney) replaced.

Introduction

The urinary organs arise in the human embryo at the age of 21 days from the transition region of the parietal to the visceral mesoderm, the intermediate mesoderm called. From the 25th day formed near the head from the intermediate mesoderm a segmented intermediate mesoderm and from this the pronephros with the first excretory units called glomeruli. Caudal ( towards the feet ) which arises from the unsegmented mesoderm, the mesonephros. Medial to the mesonephros arise from the 5th week, the gonads, lateral to the mesonephros, the Wolffian duct ( mesonephric duct ).

Structure of the mesonephros

From the tissue of the mesonephros the excretory units are formed. These are S-shaped tubules, at the one end of the glomerulus is formed and the conversation with the other end into the mesonephric duct. The end of the excretory glomerular unit covers a Kapillarknäuel and thus forms the Bowman 's capsule. From the other end of the tubules, the tubules of the kidney caused by the loop of Henle as above.

From the second month the mesonephros impressed in the human embryo as an objective in the lumbar area elongated organ. This is connected through a shaft with the rear fabric body wall. These tissues stems are called mesenteries. The unit laterally gelegenem Wolffian duct, towards the middle of the following mesonephros and middle of the body ( medial) to lying gonad is called Urogenitalleiste.

In animal embryos could experimentally the efficiency of the mesonephros are detected. During the second month the mesonephros mesonephric tubules changed such that the degenerate cranial ( head down) situated shares and some of the caudal ( towards the feet ) located close links with the gonads received. Depending on the gender form of such Shares ovary and testis.

Mesonephros and testis

In males, the mesonephric tubules develop in the caudal portion of the mesonephros to the so-called Epigenitalis and Paragenitalis. From these the one hand, the ducts of the testis arise ( efferent ) to the epididymis ( epididymis ). The most caudal portion of the mesonephric tubules located develops in males the vas deferens, the vas deferens.

Swell

• January Langmann: Medical Embryology. Thieme, Stuttgart 1980.
• Werner Kahle, Helmut Leonhardt, Werner Platzer and: Pocket Atlas of Anatomy. Vol II Thieme, Stuttgart 1979

• Urinary organ
• Organogenesis