Lecture 28 3/22/24 Flashcards
What are the endocrine requirements that must be met for sperm production?
-adequate secretion of GnRH from hypothalamus
-FSH and LH secretion from anterior pituitary
-secretion of testosterone and estrogen
Which cells produce testosterone?
Leydig cells
What is the role of Sertoli cells?
convert testosterone to estradiol
How do testosterone and estradiol act on the hypothalmus?
negative feedback on the hypothalamus leads to reduced GnRH production, which reduces LH and FSH production
Which type of center is present in the hypothalamus in males, and which is not?
-tonic center IS present
-surge center IS NOT present
Why is it important that LH is released in pulses in the male?
-high conc. of testosterone is needed in the seminiferous tubules for spermatogenesis
-Leydig cells can become refractory/reduce secretion of testosterone when exposed to sustained high levels of LH
What is puberty in the male?
ability of the male to produce and ejaculate at least 50 mil. sperm with at least 10% motility
What are the endocrine hallmarks of male puberty?
-sharp increase in testosterone
-secretion of GnRH, FSH, and LH
What pathway do sperm follow from the testis out of the body?
-rete tubules
-efferent ducts
-epididymis
-ductus deferens
-urethra
What happens to sperm in the head and body of the epididymis?
changes that allow the sperm to become fertile
What is the function of the tail of the epididymis?
storage organ for sperm prior to ejaculation
What is seminal plasma?
mixture of spermatozoa with fluids from the accessory sex glands
How does a normal testis appear on ultrasound?
hypoechoic homogenous oval structure
What are the phases of spermatogenesis?
-proliferation
-meiotic phase
-differentiation
What is the proliferation phase?
phase in which the spermatogonia undergo mitotic divisions
What is the meiotic phase?
phase in which the spermatogonia undergo meiotic division to form spermatocytes/spermatids
What is the differentiation phase/spermiogenesis?
-no divisions occur
-spermatid undergoes transformation to become a fully differentiated and specialized sperm cell
What phases occur within the differentiation phase?
-Golgi phase
-cap phase
-acrosomal phase
-maturation phase
What happens during the Golgi phase?
highly-developed Golgi apparatus gives rise to the acrosome