- capsule is thick/white/collagenous = 'tunica albuginea'
- septae devide testicular tissue into lobules
Lobules consist of:
- loose connective tissue containing clusters of Leydig cells which secrete testosterone
- seminiferous tubules which are lined by a simple columnar epithelium of supportive 'sertoli cells'
-Developing 'Germ cells' are embedded in the epithelium
Describe the structure of Leydig cells.
Leydig cells are endocrine glands. They exist as Leydig cells Islands which are clusters of steroidogenic cells embedded in highly vascular CT
What do Leydig cells secrete, and how is this accomplished?
Cell surfaces contain Leutenizing Hormone cell receptors. When LH binds to them, it triggers a G-coupled signalling pathway involving cAMP. cAMP activates protein kinases which activate cholesterol esterases which cleave free cholesterol. Free cholesterol is passed between mitochondria and SER (via LTPs) because cholesterol is not stably freely existing in cytoplasm. Instead, it's generally found as esterified cholesterol in lipid droplets.
Testosterone is secreted into loose CT and picked up by fenestrated capillaries and nearby Sertoli cells
What are myoid cells?
Slightly contractile fibroblasts which are found in the lobules of the seminiferous tubules
What are the four types of germ cells during development?