Male reproductive

From Iusmhistology

• started here on 04/06/11.

Contents 1 Male reproductive 1.1 Anatomy review 1.2 Seminiferous epithelium 1.3 Testis

Male reproductive

Anatomy review

• The testes are egg-shaped organs covered with a cartilagenous capsule called the tunica albuginea.
• The testes are divided into lobules; lobule division is incomplete and achieved by the connective tissue septae.
  • There are approximately 250 lobules in the testis.
  • Each lobule has one or several seminiferous tubules.
• The mediastinum testis is where the vessels (blood and lymphatics), nerves, and efferent duct enter and exit the testis.
  • The mediastinum testis lies at the posterior aspect of the testis.
  • Note that the mediastinum testis is connective tissue while rete testis is a collecting tubule tissue.
• Seminiferous tubules are blind ended, highly coiled, and lined with spermatic epithelium.
  • It is within the seminiferous tubules that spermatogenesis takes lace.
  • The tunica propria is the outer wall of the seminiferous tubule and is made of smooth muscle and fibroblasts.

Seminiferous epithelium

• The seminiferous epithelium (the inside of the seminiferous tubule, recall) is a stratified epithelium.
• There are multiple types of spermatogonia in the seminiferous epithelium: type A and type B.
• Type A spermatogonia are stem cells.
• Type B spermatogonia are highly mitotic progenitor cells.
  • Type B spermatogonia are connected via cytoplasmic bridges which help synchronize maturation of developing spermatozoa.
• Note that we will not differentiate between type A spermatogonia and type B spermatogonia in lab.

• Recall the order cell names in spermatogenesis: type A spermatogonia -> type B spermatogonia -> primary spermatocyte -> secondary spermatocyte -> spermatid -> spermatozoa.
  • Note that spermatids shed their residual bodies as they become spermatozoa.
• Recall the order of divisions in spermatogenesis: mitosis, mitosis / differentiation, meiosis 1, meiosis 2, differentiation.
  • Note that mitosis from type A spermatogonia to type B spermatogonia will maintain the stem cell population and will occur more than once such that many type B spermatogonia are generated.
• As spermatogonia develop, they move from the basal compartment to the adlumenal compatment.
  • We call this adlumenal movement.
  • Cells of the basal compartment: type A and type B spermatogonia, primary spermatocytes
  • Cells of the adlumenal compartment: secondary spermatocytes, spermatids, spermatozoa
• Cells and processes: type A spermatogonia undergo mitosis to become ... type B spermatogonia undergo mitosis (and differentiation) to become ... primary spermatocytes undergo meiosis 1 ... secondary spermatocytes undergo meiosis 2 ... spermatids undergo morphologic modification (differentiation) ... spermatozoa.
  • Spermatocytogenesis includes all the steps that generate an increasing number of cells (that is, type A spermatogonia through generation of secondary spermatocytes); this makes sense because of the name "cyto" = cell and genesis = "origin of".
  • Spermiogenesis is the converse of spermatocytogenesis: spermeiogenesis is the maturation of existing cells into spermatozoa (from the secondary spermatocyte stage to the spermatozoa stage).
• It takes 60-70 days for spermatogonia to progress to spermatozoa.

Testis