All the processes of urine formation are occurs in the nephron of kidneys. Urine is formed by following three stages
1) Ultrafiltration/glomerular filtration.
2) Selective reabsorption.
3) Tubular secretion.
Ultrafiltration/glomerular filtration occurs in renal corpuscle of nephron which consist of Malpighian body and Bowman's capsule. Here blood filters from blood vessels to the Bowman's capsule of nephron. The rate through which blood filters in one minute is called Glomerular Filtration Rate (GFR).
In men Glomerular Filtration Rate (GFR) is 125ml/min.
I.E. 125ML OF GLOMERULAR FILTRATE IS FORMED IN A MINUTE IN MEN.