Spermiogenesis
o Process of transformaion of spermatids into spermatozoa -
o acrosome is formed
o condensation of the nuleus - formation of neck, middle piece, and tail -shedding of most of the cytoplasm
o Fully formed spermatozoa enter the lumen of seminiferous tubules. From there they are pushed toward the epididymis by contractile elements in the wall of the seminiferous tubules
o In the beginning spermatozoa are only slightly motile - full motility is gained while in the epididymis.
o Spermatogonia and spermatids and spermatozoa remain embedded in deep recesses of sertoli cells throughout their development.
o Sertoli cells support and protect the germ cells, participate in their nutrition, and assist in the release of mature spermatozoa
Clinical Correlates
o Chromosomal abnormalities can be in number or in structure
o They may result in Birth Defects and Spontaneous Abortions:
o Abortions may be due to major or minor chromosome abnormalities.
o gene mutations account for about 8% of abortions
Most common chromosome abnormalities are :-
o Turner Syndrome.
o Down Syndrome ( Trisomy 21 )
o Klinefelter's syndrome :- trisomy - xxy - - xxxy may also occur.
In trisomy an extra chrosome is present ' total 47
Turner's Syndrome
o What is Turner syndrome?
Chromosomal condition that exclusively affects girls and women.
One of the two X chromosomes normally found in females is missing or incomplete.
o How is Turner syndrome diagnosed?
A blood test, called a karyotype, analyzes the chromosomal composition of the individual. This is the most commonly used blood test to diagnose Turner syndrome.
o What are the most common characteristics of Turner syndrome?
short stature
lack of ovarian development.
webbed neck,
arms that turn out slightly at the elbow,
a low hairline in the back of the head
cardiovascular problems,
kidney and thyroid problems,
skeletal disorders such as scoliosis
dislocated hips
hearing and ear disturbances.
o What can be done?
no "cure" for Turner syndrome.
minimize the symptoms
Growth hormone, either alone or with a low dose of androgen, will improve growth velocity and probably final adult height. Growth hormone is approved by the Food and Drug
Estrogen replacement therapy to promote development of secondary sexual characteristics. Estrogens are also important for maintaining good tissue and bone integrity.
Modern reproductive technologies have also been used to helpwomen with Turner syndrome become pregnant if they desire. A donor egg can be used to create an embryo, which is carried by the Turner syndrome woman.
Klinefelter Syndrome
normal phallus enlarged breasts
47 chromosomes, XXY
Down's Syndrome
Trisomy 21 -
Mild to moderate learning disabilities.
Severe to profound mental disability
Single transverse palmar crease
An almond shape to the eyes caused by an epicanthic fold of the eyelid
Upslanting palpebral fissures
Shorter limbs, poor muscle tone
A larger than normal space between the big and second toes
Protruding tongue.
A higher risk for congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions.
