7. Male Histo Flashcards
Testis are a paired organ that is surrounded by __________ in the the scrotum and suspended by a spermatic cord.
What then happens to the tissue that surrounds it?
Tunica albuginea.
The tunica albuginea will thicken posteriorly to form mediastinum testis, which contains the rete testis.
What surrounds the tunica albuginea?
2 layers of tunica vaginalis:
- Parietal tunica vaginalis, which lines the scrotum.
- Visceral tunica vaginalis, which lines the tunica albuginea.
Each.testis is divided into ~250 lobules.
What makes up a lobule?
- Seminiferous tubule
- Leydig cells
What is the organization of cells in the seminiferous tubules?
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Seminiferous tubules is a stratified epithelium made up of 2 populations of cells:
- Sertoli cells (support cells)
- Spermatogenic cells, which become mature sperm.
- that are surrounded by peritubular (myoid) cells which create a peristaltic wave to move spermatozoa through the tubule.
In the testis, seminiferous tubules become what?
- The end of the seminiferous tubules are located near the mediastinum. The ends become [straight tubules].
- Proximal ends have sertoli cells and distal ends have simple cuboidal cells.
- Straight tubules-> become rete testis, which is a anastomosing system in mediastinum.
What type of cells are rete testis?
- Simple cuboidal epithelium
- Low columnar epithleium
The epididymis lies along the superior and posterior surface of the testis and allows for sperm maturation, which takes 2-12 days.
What are the parts of the epididymis?
1. Head
2. Body
3. Tail
What is the head of the epididymis?
- Contains efferent ductules (pseudostratified columnar epithelium), which connect the rete testis to the head of the epididymis.
What is the body of the epididymis?
- Body contains the duct of the epididymis, which is made up of principal cells (pseudostratified columbar epithelium with steriocilia)
What is the tail of the epididymis?
Connects the duct of epididymis -> ductus deferens.
What kind of muscle surrounds the epididymis?
Smooth muscle that assists with peristalsis.
What is the ductus deferens?
Tube surrounded by loose CT, adipocytes and [pseudostratified columnar epithelium w/ stereocilia] and has a muscular wall made up of 3 muscular layers: inner and outer longitudinal layer and middle circular layer.
What is the ampulla?
- Ampulla is a dilated part of the vas deferens that leads to the prostate.
- The end will receive the duct of the seminmal vesicle, which helps to form the ejaculatory dict.
Histologically, what is different between the epididymis and vas deferens?
Lumen is folded, not smooth.
What are spermatogenic cells and how are they organized?
- Spermatogenic cells come from primordial germ cells in the yolk sac and mature into sperm.
- They are organized in layers at different stages of development BETWEEN sertoli cells inside of the seminiferous vesicles.
What is the spermatogonial phase?
- Sperm stem cells divide and become: type A spermatogonia or type B spermatogoia
- Type A: oval nuclei with basophilic, granular chromatin. They. can stay stem cells or become type B
- Type B: spherical nuclei with clumps of condensed chromatin around nucleolus. They will enter meiosis to become mature sperm.
What process occurs in spermatocyte phase?
- Spermatocyte phase -> meiosis.
- 1. Type B spermatogonia -> primary spermatocytes (2N, 4D) via mitotic division.
- Primary spermatocytes. -> secondary spermatocytes (1N, 2D)
- Secondary spermatocytes -> spermatids (1N, 1D)
What is the spermatid phase?
Spermiogenesis: spermatids become mature sperm cells. Occurs in 4 phases:
- Golgi phase
- Cap phase
- Acrosome phase
- Maturation phase
Describe what occurs in the first two phases of spermiogenesis.
- Golgi phase:
- Acrosome vesicle forms next to the nucleus. Where it forms will determine the anterior pole of the sperm.
- Centrioles move to posterior pole and begin to form axoneme of the tail of the sperm.
- Cap phase:
* Acrosome enlarges and creates a acrosome cap. Nuclear envelope will attach.
Describe what occurs in the last two phases of spermiogenesis.
- Acrosome phase: the spermatid will orient itself so that the head is embedded in the sertoli cell and points toward the basal lamina. Manchette forms from cytoplasmic microtubules.
- Maturation phase: Extra cytoplasm is removed as residual bodies, creating mature spermatozoon. The spermatids are then released from sertoli cells -> lumen of the seminiferous tubules.
What is the structure of a mature sperm?
Mature sperm is separated into a head and tail.
- Head has a flat, elongated nucleus and is covered by acrosomal cap that has hydrolytic enzymes.
Tail has three pieces:
- Middle -has the mT
- Principal- fibrous sheath that adds stability
- End- contains the axonemal complex that connects microtubules.