When boy becomes of 14 years of age then L.H. & F.S.H. hormone secretion from pituitary increases. The rise in these hormones leads to proliferation of sperm forming cells (Germ Cells) in the testis. These germ cells start multiplying under the effect of above-mentioned pituitary hormones along with assistance of other hormones as testosterones, Growth hormones, Androstenidione, insulin like growth factor-I, Thyroids hormone, paracrine hormone & growth factors. Under the control of above-mentioned hormones germs cells divide & transformed into primary spermatocytes. Then further maturation of primary spermatocytes to spermatids & then finally into mature spermatozoa (i.e. normal sperms) occurs under the control of above-mentioned hormones. After few weeks of progressive maturation inside the testis these sperms become normally motile & develop the capacity to fertilize the ovum. This total sperm cycle, from first stage to final stage of normal mature sperms is of three months. Thus to produce normal sperms testis should have normal sperm producing germ cells & normal regulating hormones. Any major hindrance in the development of these spermatozoa will lead to absent sperm production resulting into nil sperm.

Causes of Nil Sperms: The various causes of nil sperm are as follows: The various causes of low sperm count are as follows:

Hormone disorder: The various endocrine (Hormone) disorder leading to azoospermia are as follows.

(i) Hormone deficiency

of pituitary gland as L.H., F.S.H., Prolactin, thyroids hormone, hypothalmic deficiency of GnRH, Pituitary gland failure, Hypopituitarism, Idiopathic hypopituitarism, Kallman syndrome, Isolated hypogonadotropic hypogonadism, Drugs, toxins, Idiopathic hypogonadotropic hypogonadism & due to many more causes.

(ii) Obstruction in the outflow of semen (Sperms) from testis to outside through urethral opening. Many times the production of sperms in testis is absolutely normal but these sperm are unable to come out due to obstruction in the out flow tract leading to absent sperms in the semen. The various causes of obstruction are absent vas deferens, absent seminal vesicle, posttraumatic, post surgical ligation of vas deferens. After some infections, as chlamydial, gonococcal urethritis. It may also be due to post tubercular epididimo-orchitis. The sperm may also not come out of testis if the are imotile due to any of the following causes as imotile cilia syndrome, kartagener syndrome cystic fibrosis & many other rare diseases.

(iii) Absence of germ cells in testis also called sertoli cell only syndrome. In this there are no germs cells i.e. sperm forming cells in the testis. For you knowledge, I wish to inform you that in testis germ cell come to testis from neural cord area of the body during neural cord area of the body during development of fetus. So in some fetuses this migration of sperm cells do not occurs leading to testis only having testosterone forming & sertoli cells. Thus this condition is called sertoli sell only syndrome it is a developmental defect.

(v) Maturation Arrest (. Spermatid arrest): of primary spermatocytes to secondary spermatocyte, spermatids or to mature spermatozoa. Due to may local, systemic, hormonal growth factor deficiency or due to idiopathic factor. The various paracrine hormones and growth factors are essential for normal development i.e. maturation of one germ cells to multiplication of ultimately production of multiple mature, normal & motile sperms. Many other factor as infection, varicocele, drugs, chemotherapy may also lead to maturation arrest. The other causes may by developmentally defective germs cells & spermatocyte. So that they did not have inherent capacity of developing into a mature & motile sperms.

(vi) Testicular disorders (primary leydig cell dysfunction), Chromosomal (Klinefelter syndrome and variants, XX male gonadal dysgenesis), Defects in androgen biosynthesis, Orchitis (mumps, HIV, other viral, ),Myotonia dystrophica, Toxins (alcohol, opiates, fungicides, insecticides, heavy metals, cotton seed oil), Drugs (cytotoxic drugs, ketoconazole, cimetidine, spironolactone)

vii) aricocele (Grade 3 or more severe): A varicocele is a varicose vein in the cord that connects to the testicle. (A varicose vein is one that is abnormally enlarged and twisted.) Varicocele decreases sperm productions by elevating temperature of the testis, may produce higher levels of nitric oxide chemical in the testis which blocks sperm production, varicocele damages sperms directly & lastly varicocele decrease the oxygen supply to testis.