Notes

Overview Of The Male Anatomy
With dissolution of the nuclear membrane, the chromosomes align on a spindle and every member of the homologous pair moves to opposite poles of the spindle for the duration of anaphase. The resultant daughter cells are named secondary spermatocytes and contain the haploid number of chromosomes but, since every chromosome is composed of a pair of chromatids, the DNA content is still diploid. Meiotic maturation in the human requires about 24 days to proceed from the preleptotene stage to the formation of round spermatids. Meiosis commences when Form B spermatogonia drop their contact with the basement membrane and form preleptotene principal spermatocytes.
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Chromatin immunoprecipitation experiments revealed that A-MYB directly targets numerous genes involved in different aspects of meiosis, suggesting that A-MYB is a “master” transcriptional regulator of male meiosis . The complexity of the Sertoli cell’s structure and function is reflected in the complexity of its regulation. A detailed overview on the a lot of factors regulating Sertoli cell function is out of the scope of this chapter, and only a few essential functions will be discussed here. The reader is referred to the excellent book on Sertoli cell Biology for extensive details. The epididymis is a comma shaped structure composed of thin tubules that cups the posterior aspect of the testis.
Prostate Gland
Innervation is derived from the inferior portion of the hypogastric plexus, mostly to the connective tissue surrounding the gland. The scrotum is a fibromuscular pouch divided by a median septum forming 2 compartments, each and every of which includes a testis, epididymis and component of the spermatic cord. Layers of the scrotum consist of skin, dartos muscle, external spermatic fascia, cremasteric fascia and internal spermatic fascia, which is in close contact with the parietal layer of the tunica vaginalis. An erection is the stiffening and increasing of the penis that facilitates sexual arousal, even though it can also take place in nonsexual situations. The major physiological mechanism that brings about an erection is the autonomic dilation of arteries supplying blood to the penis.

Spermatids move from the testis to the epididymis and mature into sperm. Within the testis, AR is expressed in Sertoli cells, peritubular myoid cells, Leydig cells and vascular endothelial cells (( ), whereas germ cells lack AR and rely solely on somatic AR expression ( ). Hence androgens act on AR within the testicular somatic cells to help spermatogenesis.
External Male Sex Organs
The truth that activin and follistatin remain unchanged just after castration yet inhibin B in the circulation becomes undetectable strongly suggests that the gonadal feedback signal on FSH secretion is inhibin B. This is supported by studies in arcuate nucleus-lesioned monkeys maintained on a constant GnRH pulse regime, where testosterone could stop the post-castration rise in LH but not FSH (for evaluation see ). The infusion or injection of recombinant human inhibin A in several species caused a fast and precise fall in FSH secretion ( ) and inhibin A administration to castrate rams suppressed FSH levels in the absence of testosterone .
Which hormone controls the production of sperm? Three hormones are the principle regulators of the male reproductive system: follicle-stimulating hormone (FSH) stimulates spermatogenesis; luteinizing hormone (LH) stimulates the production of testosterone; and testosterone stimulates the development of male secondary sex characteristics and spermatogenesis.

These tubules are accountable for generating the sperm cells by way of a process known as spermatogenesis. It is situated at the base of your brain and it is accountable for numerous functions in your body. LH stimulates the production of testosterone, which is important to continue the process of spermatogenesis. Testosterone is also vital in the development of male characteristics, like muscle mass and strength, fat distribution, bone mass and sex drive. Semen is the fluid made by males for sexual reproduction and is ejaculated out of the body through sexual intercourse.
Seminal Vesicles, Penis, Prostate, And Bulbourethral Gland
Inside the lobules, sperm develop in structures named seminiferous tubules. During the seventh month of the developmental period of a male fetus, every testis moves by means of the abdominal musculature to descend into the scrotal cavity. This is called the “descent of the testis.” Cryptorchidism is the clinical term used when 1 or each of the testes fail to descend into the scrotum prior to birth. Several systemic illnesses are accompanied by a reduction in both serum androgen levels and sperm output, indicating that male sexual function and basic effectively-getting keep a reciprocal partnership. It has been suggested that this represents a physiologically significant mechanism, obtaining evolved to limit reproductive activity in the course of periods of illness. The possibility that acute inflammatory dysregulation of male reproductive function can lead to additional permanent challenges, such as autoimmune infertility or chronic inflammatory illness, also ought to be thought of.
They also demonstrated that the duration of any one stage was proportional to the frequency with which it was observed in the testis. A smaller amount of testosterone is also secreted by the adrenal glands in each sexes. Some correlative evidence supporting the action of inhibin on FSH secretion is the lower in inhibin production by Sertoli cells in parallel with the rise in FSH in a number of models of spermatogenic damage ( ). When the physique is cold, the scrotum shrinks and becomes tighter to hold in body heat.
They are situated inside the scrotum, which is the loose pouch of skin that hangs outdoors the physique behind the penis. Although this place tends to make the testes vulnerable to injury , it gives a cooler temperature for the organs. When a infant boy is born, he has all the parts of his reproductive system in location, but it isn't until puberty that he is able to reproduce. When puberty begins, generally involving the ages of 9 and 15, the — positioned close to the brain — secretes hormones that stimulate the testicles to create testosterone.

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