plate tectonics. noun plural but singular in construction. Tweet. geology: a scientific theory that the Earth's surface is made of very large sections that move very slowly; also: the movements of the large sections that form the Earth's surface.
The testicle is divided into parts called lobules. Each lobule contains tiny U-shaped tubes called seminiferous tubules. There are about 800 seminiferous tubules tightly coiled within the testicle. The seminiferous tubules open into a series of uncoiled, interconnected channels called the rete testis.Ducts, or tubes, connect the rete testis to a tightly coiled tube called the epididymis. The epididymis joins to a long, large duct called the vas deferens. Each testicle is held in the scrotum by a spermatic cord.he testicle is divided into parts called lobules. Each lobule contains tiny U-shaped tubes called seminiferous tubules. There are about 800 seminiferous tubules tightly coiled within the testicle. The seminiferous tubules open into a series of uncoiled, interconnected channels called the rete testis.
Sperm are produced by spermatogenesis within the seminiferous tubules. A transverse section of a seminiferous tubule shows that it is packed with cells in various stages of development. Interspersed with these cells, there are large cells that extend from the periphery of the tubule to the lumen.arly in embryonic development, primordial germ cells enter the testes and differentiate into spermatogonia, immature cells that remain dormant until puberty. Spermatogonia are diploid cells, each with 46 chromosomes (23 pairs) located around the periphery of the seminiferous tubules.