Chapter 10: endocrinology of the male and spermatogenesis

what does succesful testis function require?

• pulsatile GnRH secretion

• high concentrations of testosterone in seminiferous tubule

• low concentrations of testosterone in systemic blood

• adequate LH receptors in leydig cells

what is required for production of normal numbers of fertile sperm?

• endocrine regulation of testis

• mitotic division of spermatogonia

• meiotic divisions resulting in haploid spermatids

• morphologic transformation of spermatids into spermatozoa

leydig cells

male equivalent of follicular theca interna cells

sertoli cells

male equivalent of follicular granulosal cells

goals of spermatogenesis

• provide continual supply of male gametes through stem cell renewal

• provide genetic diversity

• provide billions of sperm each day to maximize reproduction by natural service and artificial insemination

• provide an immunologically privileged site where developing germ cells are not destroyed by the males immune system

spermatogenesis=

proliferation + meiosis + differentiation

where does spermatogenesis take place?

in the seminiferous tubules

what does differentiation consist of?

• golgi phase

• cap phase

• acrosomal phase

• maturation phase

golgi phase

acrosomic vesicle formation

cap phase

acrosomic vesicle spreading over the nucleus

acrosomal phase

nuclear and cytoplasmic elongation

maturation phase

final assembly that forms a spermatozoon

spermatozoa=

head + tail

head=

nucleus + acrosome + post-nuclear cap

tail=

middle piece + principle piece + terminal piece

what is a self-powered flagellum?

sperm tail

germ cell generations

cells of same type located at one site within seminiferous epithelium

stage

specific cellular associations

stage duration

time required for completion of one stage

cycle

progression through sequence of all stages

cycle duration

time required to complete one cycle

what varies among species?

lifespan of cells and duration of cycle

what is the spermatogenic wave?

the sequential ordering of stages along the length of the seminiferous tubule

what is potential fertility determined by?

• sperm producing ability

• viability of spermatozoa

• number of morphologically abnormals spermatozoa that he ejaculates

• number of functionally normal spermatozoa that he ejaculates

major steps of artificial insemination

• collection of semen from male

• preservation and extension of sperm

• insemination of female

what info is needed immediately after collection?

• ejaculate volume

• concentration of spermatozoa in the ejaculate

• percentage of motile sperm

what must good seminal extenders be?

• isotonic

• good buffers

• minimize cold damage

• provide appropriate nutrients

• prevent microbial growth

• maintain viability

• be relatively low in cost