This, over the fourth to the seventh week, divides into a urogenital sinus and the beginnings of the anal canal, with a wall forming between these two inpouchings called the urorectal septum. Two ducts form next to each other that connect to the urogenital sinus; the mesonephric duct and the paramesonephric duct, which go on to form the reproductive tracts of the male and female respectively.In the male, under the influence of testosterone, the mesonephric duct proliferates, forming the epididymis, ductus deferens and, via a small outpouching near the developing prostate, the seminal vesicles. Sertoli cells secrete anti-mullerian hormone, which causes the paramesonephric duct to regress.The development and maintenance of the seminal vesicles, as well as their secretion and size/weight, are highly dependent on androgens. The seminal vesicles contain 5α-reductase, which metabolizes testosterone into its much more potent metabolite, dihydrotestosterone (DHT). The seminal vesicles have also been found to contain luteinizing hormone receptors, and hence may also be regulated by the ligand of this receptor, luteinizing hormone. Microanatomy
The inner lining of the seminal vesicles (the epithelium) is made of a lining of interspersed column-shaped and cube-shaped cells. There are varying descriptions of the lining as being pseudostratified and consisting of column-shaped cells only. When viewed under a microscope, the cells are seen to have large bubbles in their interior. This is because their interior, called cytoplasm, contains lipid droplets involved in secretion during ejaculation. The tissue of the seminal vesicles is full of glands, spaced irregularly.
Short-limb skeletal dysplasia with severe combined immunodeficiency is an extremely rare autosomal recessive type of achondroplasia which is characterized by short stature,  bowing of the long bones, and generalized metaphyseal abnormalities alongside signs of SCID such as recurrent severe infections, failure to thrive, chronic diarrhea, and a notable absence of T and B lymphocytes. Around 11 cases have been described in medical literature. == References ==