The intratesticular ducts include the straight tubules (or tubuli recti), rete testis, and efferent ductules.
And the excretory gential ducts include the epididymis, ductus (or vas) deferens, and urethra.
The epididymis is a single, long convoluted duct where spermatozoa accumulate and continue to mature even further, including the development of motility.
The seminal fluid is also slightly alkaline, or basic.
Surrounding each testis is a thick capsule of connective tissue, called the tunica albuginea.
Each lobe contains one to four highly-coiled seminiferous tubules.
In this one image, we can see the various stages of spermatogenesis.
These cells are round with a large round nuclei and a pale cytoplasm.
As the cell differentiates, it moves towards the central lumen of the tubule.
The stages of differentiation can be identified based on subtle differences in the shape and staining of the nuclei.
The next stage or cell type is the primary spermatocyte.
These cells can be found at various levels between the basement membrane and the lumen, but they can be identified by their bigger cytoplasm and large nuclei that have thin threads or clumps of chromatin around them.
The secondary spermatocytes arise from the primary spermatocytes, but they’re rarely seen in images because of how quickly they divide into two haploid spermatids.
The early spermatids can be identified by their smaller size compared to spermatocytes and their very round nuclei.
They continue to get smaller as they become late spermatids with small pointed nuclei, which is the last stage seen before finally becoming mature spermatozoa.
Throughout the germinal epithelium, sertoli cells are also present, which are large columnar cells with pale, euchromatic nuclei and prominent nucleoli
The sertoli cells also secrete two hormones - inhibin and activin - which provide positive and negative feedback to the pituitary for FSH secretion.
In this image, portions of the seminiferous tubules can be seen, but there are also Leydig cells, which are typically found between the tubules in the interstitial space.
Leydig cells are large, round or polygonal cells with round nuclei and often have an eosinophilic cytoplasm because of the lipid droplets that they typically contain.
Also, in this image, we can see the spindle-shaped nuclei of myoid cells surrounding the seminiferous tubules.