Figure 5

Nuclear changes of germ cells during spermatogenesis. (A) A region of a cyst of germ cells (cystocytes) in the testis of a yellow male pupa. (B) A germ cell in the testis of a yellow-red male pupa, showing mitochondrial bodies accumulating around the nucleus (white arrow). (C) A germ cell with mitochondria that have coalesced into an ‘onion’ like structure called nebenkern (black arrow). Dark grey area within the nucleus of each cell in (A–C) is the nucleolus (indicated by black arrows in (A,B)). (D) Cross section of nuclei within a bundle of germ cells that have entered into spermiogenesis. The chromatin adjacent to the plasma membrane is becoming electron dense (black) (E) Cross section of nuclei within a bundle of spermatids whose chromatin contains thick fibrillar structures. (F) Cross section of late spermatids, whose chromatin is very electron dense; by this time, the diameter of the nuclei has decreased substantially. (G) An individual sperm with electron dense chromatin, and an acrosome at its tip (black arrow). Scale bars are 2 μm in (A), 3 μm in (B), 2 μm in (C), 1 μm in (D), and 500 nm in (G) The scale bar in (D) also applies to (E,F).