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Endocrinology of the Male and Spermatogenesis - Coggle Diagram
Endocrinology of the Male and Spermatogenesis
GnRH
Production is within the hypothalamus
In males the discharge of GnRH is in frequent, intermittent bursts
Last for a few minutes
Happens in a female after a period of basal release
LH
Secretion from the anterior pituitary gland
Bursts of GnRH causes discharge of LH
Occurs 4-8 times a day, more rapid
Acts on the Leydig cells within the testes
They are analogous to the cells of the theca interna of the antral follicles in the ovary
Becomes refectory to sustain high levels of LH
This condition is brought by sustained high concentrations of LH due to the reduction in the number of LH receptors in the Leydig cell
Produces progesterone, and most is converted to testosterone
They are the male equivalent of the follicular theca interna cells
Testosterone
Production of testosterone takes place by the same intracellular mechanism as in the female
Testosterone secretion (due to Leydig cell synthetization) is short, and the secretion is pulsatile and lasts for a period of 20 to 30 minutes
Intratesticular levels of testosterone must be higher than blood levels of testosterone for successful spermatogenesis
The role of the pulsatile nature of testosterone is not fully understood
Follicle Stimulating Hormone
Secretion from the anterior pituitary
Have lower concentrations and longer durations of pulses because of constant secretion of inhibin by the adult testis
Chronically high testosterone concentrations suppress FSH levels
Sertoli cell function is FSH dependent, so their function is compromised when FSH is reduced
Spermatogenesis
Production of fertile spermatozoa requires a few things
Endocrine regulation of the testis
Mitotic divisions of spermatogonia
Meiotic divisions resulting in haploid spermatids
Morphologic transformation of spermatids into spermatozoa
Takes place in the seminiferous tubule and consists of the sum of all cellular transformations in developing germ cells
Spermatocytogenesis
Has mitotic divisions involving proliferation and maintenance of spermatogenia
Meiosis insures genetic diversity and involves primary and secondary spermatocytes which gives rise to spermatids
It is the morphologic transformation of spherical spermatids into fully differentiated, highly specialized spermatozoa