The Male Hormones

The hypothalamus secretes gonadotropin-releasing factors, which activate the anterior pituitary gland to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH) (LH). FSH stimulates sperm production in the seminiferous tubule, whereas LH stimulates testosterone production in the testes' interstitial cells (Leydig). Secondary sex characteristics attributed to testosterone include the deepening of the voice, growth of the genitalia and growth of hair on the chest pubis, axilla, and face, muscle mass development, bone strengthening, and enlargement of the penis, scrotum, testes, prostate gland, and seminal vesicle.

Male Sexual Response

The physiologic reaction in both men and women is comparable and normally follows a four-phase pattern, regardless of the type of sexual stimulation.

Excitement: The person experience sexual arousal with specific change such as the erection of the penis in males.

Plateau: Physiologic changes of the excitement phase level off.

Orgasm: The tension that built up during the previous two phases is released.

Resolution: The body returns to the physiologic non-stimulated state.

The relation of Male Reproductive system to Conception and Pregnancy. How Does the Male Reproductive System Work?

• Makes semen.
• Releases semen into the reproductive system of the female during sexual intercourse.
• Produces sex hormones, which help a boy develop into a sexually mature man during puberty.

When a baby boy is born, he has all of the components of his reproductive system in place, but he cannot procreate until he reaches puberty. When puberty begins, which typically occurs between the ages of 9 and 15, the pituitary gland, which is located near the brain, secretes chemicals that drive the testicles to make testosterone. Many bodily changes occur as a result of testosterone production.

Although the timing of these changes varies from boy to boy, the stages of puberty generally occur in the following order:

• The scrotum and testes expand during the initial stage of male puberty.
• Following that, the penis lengthens and the seminal vesicles and prostate gland expand.
• Hair growth begins in the pubic area and progresses to the face and underarms. The voice also deepens during this period.
• During puberty, boys experience a growth spurt as they reach their adult height and weight.

Every day, a male who has entered puberty produces millions of sperm cells. Each sperm is incredibly tiny, measuring about 1/600 of an inch (0.05 millimeters long). Sperm develop in the testicles in a network of small tubes known as the seminiferous tubules. These tubules contain simple spherical cells upon birth. These cells convert into sperm cells as a result of testosterone and other hormones throughout adolescence. The cells divide and transform until they resemble tadpoles, with a head and a short tail. The head houses genetic material (genes). The sperm then enter the epididymis to complete their development.

The sperm next travels to the vas deferens, often known as the sperm duct. When a guy is sexually excited, the seminal vesicles and prostate gland produce a whitish fluid called seminal fluid, which combines with sperm to form semen. When a man gets sexually excited, his penis, which usually hangs limp, becomes hard. The tissues in the penis fill with blood, making it stiff and erect (an erection). The erect penis' hardness makes it easier to insert into the female vagina during sex. When the erect penis is stimulated, the muscles that surround the reproductive organs contract, forcing the sperm down the duct system and urethra.. Ejaculation is the process by which sperm exits the male's body via the urethra. A person's ejaculate can contain up to 500 million sperm.

Millions of sperm "swim" up from the vagina through the cervix and uterus to meet the egg in the fallopian tube when semen is ejaculated into a female's vagina. It just takes one sperm to fertilize an egg. This fertilized egg is now known as a zygote, and it includes 46 chromosomes, half of which came from the egg and half from the sperm. The genetic material from the male and female unite to form a new individual. The zygote divides frequently as it grows in the female uterus, eventually growing into an embryo, a fetus, and finally a newborn baby.

Gametogenesis

Primordial Germ Cells

Fertilization is the process by which the male gamete, the sperm, and the female gamete, the oocyte, combine to form a zygote. Gametes are formed from primordial germ cells (PGCA), which are found in the epiblast during the second week and migrate to the yolk sac wall. These cells begin to migrate from the yolk sac toward the developing gonads during the fourth week, arriving by the end of the fifth week. Mitotic divisions multiply during their migration and when they reach the gonad. Germ cells undergo gametogenesis, which includes meiosis, to reduce the number of chromosomes and cytodifferentiation to complete their maturation during preparation or fertilization.

Spermiogenesis

It is the maturation of male gametes in the wall of seminiferous tubules that begins during puberty and includes a series of cyclical changes for the conversion of primordial male germ cells into spermatoge. Spermatogenesis is divided into three stages:

• Spermatocytogenesis (Mitosis)
• Spermiogenesis
• Meiosis

Spermatocytogenesis (Mitosis)

Mitosis divides primordial germ cells, resulting in dark type. A spermatogonia is a type of stem cell. By mitosis, each dark type A cell produces two daughter cells, one dark type and spermatogonium and the other light type A spermatogonium. The dark type A cell is preserved as a reserve for the next cycle's repeat. The bright type A cell differentiates further and divides mitotically to generate two type B spermatogonia. Mitosis produces around four generations of type B cells. Each type B cell divides further into two primary spermatocytes, each with 46 chromosomes (44 autosomes + XY sex chromosomes).

Meiosis

From then on, each main spermatocyte undergoes initial meiotic or reduction division, yielding two daughter cells, the secondary spermatocytes. Secondary spermatocytes have 23 chromosomes (haploid) and come in two varieties: one with 22 autosomes plus the X chromosome and the other with 22 autosomes plus the Y chromosome. In contrast to the egg, both secondary spermatocytes have an equal quantity of cytoplasm and are equally active. Secondary spermatocytes complete this third meiotic division nearly rapidly, culminating in the creation of spermatids. As a result, each primary spermatocyte produces four spermatids, two of which are X-bearers and the other two are Y-bearers. Spermatids are then transformed into spermatozoa. Each daughter cell of the first meiotic division in both spermatogenesis and oogenesis has haploid chromosomes with 2 N DNA strands, whereas each daughter cell of the second meiotic division has haploid chromosomes with 1N DNA strands because DNA replication does not occur in meiosis II.

Spermiogenesis

Spermatogenesis is the morphological transformation of spermatids into spermatozoa without further cell division. Each spermatid begins with a spherical nucleus, a Golgi apparatus, a centrosome with two centrioles, numerous mitochondria, and an abundance of cytoplasm.

The flattened vesicles of the Golgi apparatus containing acrosomal granules coalesce and spread over the anterior pole of the nucleus to form the head cap as the conversion progresses. Two-thirds of the nucleus is covered by the skull cap. The centrosome is located at the nucleus's posterior pole, opposite the head cap, and divides into two centrioles, which give rise to the axial filaments of a spermatozoon's body and tail. The two centrioles delimit the spermatozoon's main component or body; the posterior one forms the ring centriole. The mitochondrial sheath is formed by the accumulation of all mitochondria in a spiral fashion around the central piece. Finally, the spermatid elongates and the nucleus emerges from the cytoplasm but remains within the cell membrane, forming the spermatozoon's head. The body or the central component is surrounded by cytoplasm, but the majority of the cytoplasm content is extruded from the cell as leftover bodies.

The heads of immature spermatozoa sink into depressions on the surface of Sertoli cells. When they attain maturity, they are released into the lumen of the seminiferous tubules. In humans, the entire process of converting from type A spermatogonia to spermatozo takes about 64 days. Spermatocytosis takes around 16 days, Meiosis I takes about 8 days, Meiosis II takes about 16 days, and spermatogenesis takes about 24 days.

Fully developed spermatozoa in the seminiferous tubules are non-motile and are suctioned into the epididymis. The fluid product of the testis is reabsorption by the mucous membrane of their testes, efferent ductless and proximal part of the canal of epididymis. As a result, the epididymis experiences negative pressure, which aids in the movement of spermatozoa from the seminiferous tubules to the epididymis.

Oogenesis

This is the process by which primordial female germ cells mature from primary oocyte to mature ovum. Meiosis, which consists of two successive divisions, influences maturation. Meiosis is a heterotypical or reduction division, while Meiosis II is a homotypical division of the first, which has already been reduced. A number of primary follicles, approximately 5-12 follicles, mature after adolescence in each monthly menstrual cycle, which is associated with the maturation of germ cells. In general, just one follicle matures fully and ruptures each month, spilling the oocytes from the ovary's surface. The remaining follicles develop atretic alterations.

Process of Maturation

A primary ovarian follicle is made up of a big center cell called the primary oocyte that is surrounded by a layer of flattened follicular cells. The primary oocyte, which has already completed the prophase of the first meiotic division, has an initial diameter of roughly 35 microns. The oocyte's nucleus is eccentric in position and contains a diploid number of chromosomes, including 44 autosomes and 2X sex chromosomes.

The primary oocyte grows in size as the follicle matures, eventually reaching a diameter of about 140 microns. Follicular cells become cuboidal and divide into several layers of cells. Meanwhile, glycoprotein-rich amorphous materials accumulate between the inner layer of follicular cells and the oocyte. These chemicals combine to produce the zona pellucid, a full striated membrane that surrounds the oocyte. The zona pellucida can be formed by follicular cells, oocytes, or both. Numerous microvilli of the main oocyte project into follicular cell processes. These processes give the zona a striated appearance and aid in the delivery of nourishment to the egg. The main oocyte.

As the follicle grows in size, many fluid-filled gaps form between the follicular cells. These spaces merged into a single cavity known as the antrum folliculi, and the fluid is known as the liquor folliculi. As a result, the follicular cells separate into an outer layer known as the cumulusvericus and an inner layer known as the cumulusvericus, but both layers are continuous at the time of replacement. The main oocyte is surrounded by a cumulus. Outside the follicle's stratum granulosum, stroma cells of the ovary form a heath known as the colliculi, which differentiates into two layers: an inner vascular and cellular layer known as the tunica interna and an outer fibrous layer known as the tunica externa. A basement membrane exists between the interna and stratum granulosum cells. The main oocyte from the dictyotene stage completes the first meiotic division that began during fetal development at this stage. The nuclear membrane dissolves, and the chromosomes organize themselves in homologous pairs at the achromatic spindle's equal to. The spindle is located eccentrically close to one of the oocyte's poles. Following the crossing, the chromosomes divide, with one member of each pair passing centrally and the other passing outwards, separating from the egg to create the first polar body. This division results in the production of two daughter cells, each containing 23 chromosomes (haploid number, 22autosomes and one X chromosomes). The nuclear division is equal, while the cytoplasmic division is not. The secondary oocyte is a big cell that receives ample cytoplasm from the mother cell. The other cell is small, with little cytoplasm, and serves as the first polar body. The polar body is housed in the perivitelline space, which has formed between the zona pellucida and the secondary oocyte's cell membrane. The Graafian follicle is a mature follicle that contains a secondary oocyte and the first polar body.

The secondary oocyte immediately begins the second meiotic division phase. The haploid chromosomes reorganize themselves at the spindle's equator, which is closest to the cell. The Graafian follicle grows to around 10mm in size and appears just beneath the surface of the ovary.