Histology of Reproductive System Flashcards
What is the male reproductive system responsible for?
- Continous production, nourishment, and temporary storage of haploid male gamete (spermatozoa or sperm)
- the synthesis and secretion of male sex hormones (androgens)
What does the male reproductive system consist of?
- Testes-produce sperm and synthesize and secrete androgens
- The epididymis, vas deferens, ejaculatory duct, and a segment of the male urethra which form the duct system responsible for transport of spermatazoa to the exterior.
- The seminal vesicle and prostate gland whose secretions form the bulk of the semen and provide nutrients to ejaculated spermatozoa.
- The penis the copulatory organ, formed of erectile tissue.
What is each testis enclosed by?
A tough connective tissue covering called the tunica albuginea.
What do fibrous septa do?
They project into the testicular mass, dividing the tissue into 250 to 300 lobules. Each lobule contains one to four seminiferous tubules.
How many seminiferous tubules does each lobule contain?
250 to 300.
How long is each seminiferous tubule, what does it look like?
It is 80cm long, it is U-shaped with the two ends opening into the rete testis.
What is the rete testis?
A network of channels that collect the products of the seminiferous epithelium (sperm, secretory proteins, fluid, and ions).
What is the space in between the seminiferous tubules occupied by?
The abundant blood vessels and aggregates of the andorgen-producing Leydig cells.
What are leydig cells?
They are androgen producing and respond to LH and produce testosterone.
What are the cells of the seminiferous tubule central lumen?
It is lined by a specialized seminiferous epithelium containing:
- somatic sertoli cells
- the spermatogenic cells
Describe the histology of sertoli cells?
They are columnar epithelial cells containing a light-staining nucleus with a prominent nucleolus.
Where do sertoli cells extend from?
From the basal lamina to the lumen of the seminiferous tubule and are connected by tight junctions to form a basal and adluminal compartment within the tubule.
What are tight junctions between sertoli cells components of?
Blood-testis barrier
What is the function of the blood-testis barrier?
It protects developing spermatogenic cells located within the adluminal compartment from autoimmune reactions.
What is the function of sertoli cells?
To support cells to the developing germ cells in the tubule, they phagocytize residual germ cell cytoplasm, regulate the release of mature spermatozoa and secrete androgen binding protein in response to FSH stimulation.
What does ABP function to do?
It concentrates the testosterone produced by the Leydig cells in the seminiferous tubule to stimulate spermatogenesis.
What do the spermatogenic cells include?
The spermatogonia, spermatocytes, and spermatids.
Describe spermatogonia?
They are diploid stem cells of the testis. They have small dense oval nuclei and are closely associated with the seminiferous tubular wall within the basal compartment of the tubule.
What do the spermatogonia do?
They divide by mitosis to generate two daughter cells. one daughter cell initiates a spermatogenic cell sequence (spermatogenesis). The other cell becomes a spermatogonium with self-renewing capacity and is soon able to divide and initiate another spermatogenic cell sequence.
What do spermatogonia that enter the spermatogenesis cell sequence do?
They divide and give rise to primary spermatocytes (also diploid cells)
What do primary spermatocytes do?
They enter meiosis I and give rise to the secondary spermatocytes (haploid cells). These cells in turn differentiate into haploid spermatids during meiosis II.
How do you distinguish between primary and secondary spermatocytes in HandE sections?
TRICK QUESTION
you cant
Describe the histology of the spermatocytes.
They are located away from the tubular wall with the adluminal comparment and can be distinguished by their large nuclei containing dark-staining chromatin.
Describe the histology of spermatids.
They are even closer to the lumen of the tubule than speratocytes. They may be identified by their small dense dark-staining nuclei that can appear round in an early spermatids and oblong in the late spermatids.
What is spermatogenesis?
The process of sperm cell development. During spermatogenesis, the seminiferous epithelial cells undergo successive mitotic and meiotic divisions to produce spermatozoa.
What is spermiogeneisis?
The last step of spermatogenesis. Spermatids undergo a dramatic change in form during speriogenesis-into the streamline spermatozoa adapted for fertilization.
What does spermiogenesis involve?
Nuclear condensation, formation of the acrosomal cap, and development of a tail to ultimately form the mature spermatids that are released into the lumen of the tubule.
Are mature spermatids motile or immotile?
They become nonmotile sperm upon release into the seminiferous tubular lumen and are propelled to the epididymis where they undergo a maturation process resulting in the acquisition of forward motility leading to fertilization capability.
What is the epididymis?
A highly elongated and coiled tubules (about 6 meters in length in the adult human) where sperm mature and are stored.
What are the three major segments of the epididymis?
THe head body and the tail
Describe the histology of the epididymis?
It is pseudostratified columnar with long and branched sterocilia.
What does the epitheliym of the epididymis consist of (2 major cell types)?
- Columnar principal cells, extending from the lumen to the basal lamina. The apical domain of the principal cells displays banched stereocilia.
- Basal cells associated with the basal lamina. Basal cells are regarded as the undifferentiated precursors of the principal cells (stem cells).
Describe the difference in histology of the epididymis from the initial to terminal portions.
The initial portion of the epididymis are surrounded by a circular layer of smooth cells. The terminal portion (body and tail) display an increase in thickness of the inner circular smooth muscle layer and the development of an outer longitudinal smooth muscle layer.
What is the vas deferens?
A 45 cm long muscular tube that is continuous with the end of the epididymis
What is the lining of the vas deferens consist of?
pseudostratified columnar with stereocilia similar to that of the epididymis, and is supported by a connective tissue lamina propria with elastic fibers.
What does the muscular wall of the vas deferens consist of?
Inner and outer layers of longitudinally oriented muscle separated by a middle circular layer.
What does the external layer of the vas deferens consist of?
Loose connective tissue and adipose cells
What is the ampulla of the vas deferens?
The dialated portion of the vas deferens, it leads directly into the prostate gland.
What does the ampullar fuse with?
with the duct of the seminal vesicle, forming the ejaculatory ducts that pass through the prostate gland to empty secretion into the prostatic urethra.
What is the prostate?
The largest accessory reproductive gland.
What is the prostate surrounded by?
a capsule that consist of 30 to 50 branched tubuloalveolar glands that empty their contents into the prostate urethra.
What are the glands of the prostate surrounded by?
Smooth muscle cells and connective tissue
What are the three specific zones of the smooth muscle cells and connective tissue that surround the prostate glands?
- A transition zone closest to and surrounding the prostatic urethra.
- A central zone
- A peripheral zone
What are prostate glands lined by?
A combination of simple and pseudostratified columnar epithelial cells.
What does the lumen of the prostate glands contain?
they contain concretions (corpora amylacea) rich in glycoproteins that are sometimes a site of calcium deposition.
What do the glands of the prostate produce?
A zinc-rich alkaline fluid that neutralizes the acidity of the vagina, provides nutrients and transports the sperm, and liquefies semen.
What is benign prostate hyperplasia (BPH)?
It is a condition that occurs with aging and is a noncancerous enlargment of the prostate gland that can restrict the flow of urine through the prostatic urethra. The cells and stroma of the periurethral central and transitional zones undergo hyperplasia in older men to produce this condition.
What happens of the cells and stroma of the periurethral central and transitional zones as a man gets older.
The cells and stroma of the periurethral central and transitional zones undergo hyperplasia in older men to produce this condition.
Describe prostate cancer.
70-80 percent originate from the main prostate glands of the peripheral zone, farthest from the urethra. Urinary symptoms are not present at the early stage and tumor growth is often detected by digital palpation of the prostate, by elevated serum levels of prostate specific antigen, or by back pain caused by vertebral metastisis.