Chapter 13: Why Ask Y?: The Male Reproductive System Summary

Parts of the male reproductive system

The penis and scrotum are the visible parts of the male reproductive system. The penis is the forward projection from the male reproductive site.

The scrotum is the skin pouch outside the body found below the penis that holds testis and. The left scrotum side hangs lower than the right scrotum to host the long spermatic chord. The scrotum has two layers: the outer skin(integument) and the inner layer of muscles (dartos Tunis).

The foreskin (prepuce) is skin fold found at the tip of the penis. The foreskin is removed during circumcision.

The testis is the oval-shaped glands found within the scrotum.

The tunica albuginea is the fibrous capsule that covers each testicle and proceeds into the gland forming partitions that divide the testis into many lobules. The lobules have seminiferous tubules which are sites for sperm production.

Leydig cells are located between interstitial cells and they produce the sex hormone n men called testosterone.

The tubules from every lobule combine at the mediastinum testis region and straighten to form the rete testis network that proceeds to efferent ducts. These ducts then transport sperms into the epididymis.

Epididymis combines with vas deferens ducts that transport sperms into the spermatic cord.

Seminal vesicles are located under the bladder and produce a basic fluid containing amino acids, vitamins, fructose, and prostaglandins that nourish sperms as they get into ejaculatory ducts.

The prostate gland produces a thin substance that moves ahead of sperms during ejaculation. This substance is alkaline to reduce vaginal acidity and prepare it to accommodate sperms.

The Cowper’s glands are located on the urethral sides. They produce an alkaline lubricant before ejaculation.

During an erection, spongy erectile muscles of the penis (corpus spongiosum and corpus carvenosum tissues) accept blood and swell making it rigid and allow it to enter the female vagina.

Chromosome production for fertilization

Sperm and ova are produced through meiosis process. Meiosis has 2 divisions:

The reduction division divides diploid cells with two chromosome sets into haploid cells with one chromosome set. This is the first division.

The next process is mitosis division where haploid cells are divided into four cells with one chromosome set.

The steps of meiosis to produce gametes include the following:

Interphase: The spermatocyte in male and oocyte in female (diploid cells) undergoes a constant activity (resting stage). The DNA in chromatin replicate.

 Prophase 1: Nuclear structures such as nucleoplasm, nucleoli, and plasma membrane disappear. The centrosome in the cell divides into two centrioles which move to opposite sides of the cell and form poles. Cell structures start appearing in nuclear. Chromosomes form when chromanemata contract.

Metaphase 1: Tetrads are arranged and centromeres attach spindles.

Anaphase 1: There is the separation of chromosomes when spindles migrate to opposite sides of the cells.

Telophase I: Spindle fibers disappear while the nucleoplasm and nuclear membrane appear to generate a new cell. The cytoplasm divides equally to produce two cells.

Interkinesis:  Separation of cytoplasm occurs. Two haploid cells are formed with half the chromosome number.

Prophase II: This is the second meiosis phase. Nuclei structures disappear and poles appear.asters and spindle form in the nuclear region.

Metaphase II: The chromatids are lined up along the plane and they are attached to spindles by centromeres.

Anaphase II: There is chromatid separation and migration to the poles along with the spindles.

Telophase II: When chromosomes are at the poles, asters, and spindles vanish allowing new structures in the nuclear to appear. The chromosomes return to chromatin after uncoiling.

Revision

What are the components of the male reproductive system?
Testes, the duct system, glands, and external genitalia

What is the duct system inside the testes called?
Seminiferous tubules

What happens inside of them?
Sperm is produced

What is the name of the process of sperm development?
Spermatogensis

Broadly, how does this process work?
Well it begins at puberty and goes till old age basically. It begins at the outer layer of the seminiferous tubules and works its way towards the lumen where the sperm is finally released

What are the sperm stem cells?
Spermatogonia

What do they have to undergo to mature?
Mitosis

What do they then become?
Spermatocytes

What do they hav eto undergo and mature?
Meiosis

What do they become?
spermatids

What happens to them?
Undergo physical maturation

This happens with the effort to become what?
Spermatoza or sperm

What are the three parts of a matured sperm?
Head, middle part, tail

What makes up the head?
It has a nucleus in which it storees chromosomes for fertilization. It also has an acrosomal cap that is essential for fertlization

What makes up the middle part?
Only a mitochondria that is used to generate energy ATP so it can move the tail

What is another name for the tail and what is its purpose?
Flagellum that is used more the cell as a whole

What are the functions of the Sertoli cells?
The Sertoli cells promote spermatogenesis by phagocytizing cytoplasam shed by developing sperm and nutrients and chemical stimuli for the sperm. They also maintain a blood-testes barrier in which the Sertoli cells create tight junctions

What is so special about Leydig Cells?
They are located outside of the seminiferous tubules but are instead in the connective tissue surrounding them

What do Leydig cells even do?
Stimulated by the hormone LH to produce testosterone

What are the functions of testosterone?
It establishes two male characteristics (increased muscle mass, and facial hair), promotes spermatogeriesis, promotes libido, and maintains the glands and organs of the male reproductive tract

How is the sperm delivered
The duct system

What are the functions of the testes?
To produce sperm and produce testosterone

What is the pathway that sperm take?
Epidiymis, ductus deferes, ejactualory duct, urethra

What is the function of the epididymis?
To protect sperm, store sperm, and recycle damaged sperm

What is included in the wall of the ductus deferens?
Smooth muscle

What is it used for?
The smooth muscle is used to propel semen through the inguinal canal and spermatic cord

What is the function of the inguinal ligament and canal?
To break through the anterior abdominal wall so that the spermatic cord can pass

What does the ejaculatory duct pass through?
The prostate gland to the urethra

What does the prostate gland secrete into the urethra?
Prostate fluids

How does sperm get its fluid?
From several glands that secrete fluid throughout the duct system

What are the three glands that secrete this fluid?
Seminal vesicles, prostate glands, bulbourethral glands

What produces the most seminal fluid?
Seminal vesicles

How much does it produce?
60%

How much does the prostate gland produce of semen?
20-30% of semen volume

What does the penis release?
Semen or urine