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cells and interstitium. The morphology and function of testes in patients with

KFS at various stages of life are described in the table given below.

Seminiferous

tubules

Sertoli

cells Germ cells Leydig cells

Serum

testosterone

Fetus Normal Normal Reduced Normal –

Mini-

puberty

Normal Normal Reduced Normal Reduced

Childhood Normal Normal Reduced – –

Puberty Hyalinization

and fibrosis

Reduced Reduced Pseudohypertrophy Initially

normal, later

decline

Adulthood Hyalinization

and fibrosis

Reduced Reduced/

absent

Pseudohypertrophy Reduced

69. What is the influence of puberty on testicular function in patients with KFS?

Although the damage to testes initiates in utero in patients with KFS, there is

accelerated testicular damage during midpuberty. The onset of puberty is nor-

mal in most patients with Klinefelter’s syndrome, but majority have incomplete

development of pubertal events. With reactivation of HPG-axis at the onset of

puberty, there is an increase in testicular volume (approximately up to 6 ml)

along with rise in serum testosterone levels. However, the rise in serum testos-

terone is accompanied with accelerated hyalinization and fibrosis of seminifer-

ous tubules and degeneration of Sertoli cells. This results in regression of

testicular volume to a mean size of 3 ml. The cause for accelerated testicular

damage during puberty is not clear; however, elevated levels of gonadotropins,

increased intratesticular estradiol levels, and alteration in intratesticular testos-

terone/estradiol ratio have been implicated.

70. Why is there testicular failure in patients with Klinefelter’s syndrome?

Ten to 15 % of the genes present in X chromosome are expressed in testes.

Overdosage of genes from the extra X chromosome/s is the likely mechanism

for testicular failure in patients with KFS. The genes which are implicated in

testicular failure are most probably located in the non-PAR region of X chro-

mosome (which escape lyonization) and are expressed in testes. Overdosage of

genes from the PAR region is unlikely to be the cause of testicular failure in

patients with KFS, as evidenced by normal testicular function in individuals

with 47, XYY who also have three copies of genes in the PAR region.

7 Delayed Puberty