Male Repro Part 1

Male reproductive system

The system responsible for producing spermatozoa and male sex hormones and for delivering sperm during reproduction.

Testes

Organs that produce spermatozoa and male sex hormones, particularly testosterone.

Two main functions of the testes

Production of spermatozoa and production of male sex hormones (testosterone).

Tunica albuginea

Fibrous covering of the testis that forms septa extending inward.

Septa

Partitions formed from the tunica albuginea that divide the testis into compartments.

Mediastinum

Area of the testis where the septa converge and where the rete testis is located.

Seminiferous tubules

Tubules within the testis where spermatogenesis occurs.

Rete testis

Network that receives sperm from the seminiferous tubules and connects with the efferent ducts.

Efferent ducts

Ducts that carry sperm from the rete testis toward the epididymis.

Epididymis

Structure associated with the testis where sperm undergo maturation and are stored.

Caput epididymis

Head region of the epididymis involved in sperm maturation.

Corpus epididymis

Body region of the epididymis involved in sperm maturation and secretion of substances for sperm quiescence.

Cauda epididymis

Tail region of the epididymis involved mainly in sperm storage.

Sperm quiescence

A state in which sperm are maintained in a relatively inactive condition while in the epididymis.

Ductus deferens

Duct that transports sperm from the epididymis toward the urethra.

Testicular parenchyma

Functional tissue of the testis divided into vascular/interstitial and seminiferous tubular compartments.

Vascular and interstitial compartment

The compartment outside the seminiferous tubules containing structures such as Leydig cells.

Basal compartment

The compartment inside the seminiferous tubules near the basement membrane where developing germ cells begin.

Adluminal compartment

The compartment inside the seminiferous tubules toward the lumen containing more developed germ cells.

Sertoli cells

Cells that provide structural and metabolic support to developing sperm and maintain the environment needed for sperm development and maturation.

Functions of Sertoli cells

Support developing sperm; maintain the sperm-development environment; secrete substances that initiate meiosis; produce androgen-binding protein; secrete inhibin; and release anti-Müllerian hormone.

Androgen-binding protein (ABP)

A substance secreted by Sertoli cells that concentrates testosterone.

Inhibin

Hormone secreted by Sertoli cells.

Anti-Müllerian hormone (AMH)

Hormone released by Sertoli cells.

Leydig cells

Cells located in the space between seminiferous tubules that produce testosterone.

Blood-testis barrier (BTB)

A physical barrier between the blood vessels and seminiferous tubules formed between Sertoli cells.

Functions of the blood-testis barrier

Controls passage of molecules and prevents movement of spermatozoa into the interstitium.

Germ cells

Cells that develop through spermatogenesis and eventually become mature spermatozoa.

Spermatogonia

Germ cells that undergo successive mitotic divisions during spermatogenesis.

Primary spermatocytes

Germ cells that undergo the first meiotic division.

Secondary spermatocytes

Cells formed after the first meiotic division.

Spermatids

Cells formed after the second meiotic division that later undergo spermiogenesis.

Spermatozoa

Mature male gametes produced at the end of spermatogenesis.

Spermatogenesis

The process by which male spermatogonia develop into mature spermatozoa.

Spermatocytogenesis

The successive mitotic and meiotic divisions involved in the development of germ cells.

Spermiogenesis

The maturation or metamorphic change of spermatids into spermatozoa.

Mitosis

Cell division involved in the multiplication of germ cells during spermatocytogenesis.

Meiosis

Reduction division that changes the chromosome number from diploid (2n) to haploid (n).

First meiotic division

The meiotic division after which secondary spermatocytes are formed.

Second meiotic division

The meiotic division after which spermatids are formed.

Phases of spermiogenesis

Golgi phase, cap phase, acrosomal phase, and maturation phase.

Testosterone in spermatogenesis

Essential for the growth and division of testicular germ cells.

Luteinizing hormone (LH)

Stimulates Leydig cells to secrete testosterone.

Follicle-stimulating hormone (FSH)

Stimulates Sertoli cells and is required for the conversion of spermatids into sperm during spermiogenesis.

Estrogens in spermatogenesis

Estrogens formed from testosterone by Sertoli cells when stimulated by FSH are probably also essential for spermiogenesis.

Growth hormone in spermatogenesis

Controls background metabolic functions of the testes and specifically promotes early division of spermatogonia.

Hormones stimulating spermatogenesis

Testosterone, luteinizing hormone, follicle-stimulating hormone, estrogens, and growth hormone.

Puberty

The age in postnatal life when the gonads produce gametes and sex hormones in sufficient quantities to enable an animal to reproduce.

Main characteristics of puberty

Initiation of the ability to release mature germ cells, increased gonadotropin secretion, onset of reproductive capacity, and gradual maturation of the reproductive system.

Puberty vs sexual maturity

Puberty is the onset of reproductive capacity, while sexual maturity is the state of full reproductive capacity.

Age of puberty in dogs

6–12 months.

Age of puberty in toms

5–7 months.

Age of puberty in boars

5–6 months.

Age of puberty in bulls

10–12 months.

Age of puberty in stallions

18–24 months.

Age of puberty in rams

6–10 months.

Age of puberty in bucks

5–6 months.

Sexual maturity in dogs

About 8 months.

Sexual maturity in toms

About 9 months.

Sexual maturity in boars

About 8–9 months.

Sexual maturity in bulls

About 3–4 years.

Sexual maturity in stallions

About 3–4 years.

Sexual maturity in rams

About 18–20 months.

Sexual maturity in bucks

About 8–12 months.