Penguins do not have intromittent organs. The testes seem to demonstrate extensive morpholical changes throughout the year, the height of such size change during the breeding season. Dr. D. G. Ainley recorded similar data with Adelie penguins. This increase in testis volume occured over the 8 stages of spermatogenesis. A row of spermatogonia and Sertoli cells ring the seminiferous tubule next to the basement membrane.
Primary spermatocytes are present in an irregular row toward the lumen.
The lumen is filled with sytoplasm. There is a basal row of spermatogonia and Sertoli cells. Up to one-half the primary spermatocytes in a given tubule cross section are in the stage of synapsis where chromatin is concentrated to one side of the nucleus. A basal row of spermatogonia and Sertoli cells ring the basement membrane. Towards the lumen two to three rows of primary spermatocytes are in synapsis.