Seasonal histological effects on the Leydig and Sertoli cells in the testis of indigenous dogs (Canis Familiaris)

  • Amer M. Hussin College of Veterinary. Medicine, University of Baghdad, Iraq
  • A. G. Al-Haaik College of Veterinary Medicine, University of Mosul, Iraq
  • Nazih W. Zaid College of Veterinary. Medicine, University of Baghdad, Iraq


This study was performed on twenty adult male dogs aged 2-3 years old. Samples of testis tissue were taken during the four seasons in 2016 in Iraq. Specimens were fixed in 10% formalin.  Routine histological techniques were carried out for light microscopy. H&E and PAS stains were used. During active seasons (spring and autumn) the study revealed a significant increase in the number and diameter of Leydig and Sertoli cells compared to other inactive seasons (summer and winter). Cytological indications of mitotic events of Leydig cells were clearly observed, whereas, Sertoli cells never showed any mitotic divisions. The basement membrane of seminiferous tubules appears wavy with impacts of irregular gates of cellular penetrations. It was characterized by a dynamic, flexible structure, and can respond easily to the cellular mechanical pressure. The new generation of Leydig cells was derived either from the differentiation of interstitial fibroblast-like cells or from the mitosis of Leydig cells themselves; whereas the new generation of Sertoli cells was provided only by the differentiation of interstitial fibroblast-like cells. The study suggested that, after stimulation, the compensatory fibroblast-like cells can penetrate the basement membrane and then differentiate to Sertoli cells, as the similarity between the two cells were very large. It was concluded firstly that the proliferation of Sertoli cells within the seminiferous tubules was done only by the penetration and differentiation of the interstitial fibroblast-like cells and not by mitosis of Sertoli cells themselves.


1-Mesher AL. Junqueira's Basic Histology.12th ed. McGraw Hill Medical. (2010); Pp: 373.
2-Samuelson DA. Textbook of veterinary histology. Saunders, Elsevier. China. (2007); Pp:72-73.
3-Johnson L, Thompson DL. Age-related and seasonal variation in the Sertoli cell population, daily sperm production and serum concentrations of follicle-stimulating hormone, luteinizing hormone and testosterone in stallions. Biol. Reprod. (1983); 29(3): 777-789.
4-Johnson L, Nguyen HB. An annual cycle of the Sertoli cell population in adult stallions. J. Reprod. Fertil. (1986); 76(1): 311-316.
5-Johnson L, Thompson DL. Seasonal variation in the total volume of leydig cells in stallions is explained by variation in cell number rather than cell size.Biol. Reprod. (1986);35(4): 971-979.
6-Johnson L, Varner DD,Tatum ME, Scrutchfield WL. Season but not age affects sertoli cell number in adult stallions. Biol. Reprod. (1991);45(3):404-410.
7-Ganong WF (2009). Ganong's Review of Medical physiology.23th ed. McGraw Hill Companies,Inc
8-Blankenship TN, Given RL.Penetration of the uterine epithelial basement membrane during blastocyst implantation in the mouse. The anatomical record. V. 233, Issue 2 (1992):196-204. 9-AVMA (2013). Guidelines for the Euthanasia of Animals: /KB/Polices/Documents/euthanasia.pdf.
10-Suvarna SK, Christopher L, Bancroft JD. Theory and practice of histological technique, 3rd ed., N.Y. Churchill Livingstone. New York, (2013); Pp: 109-121
11-Culling CFA, Allison RT, Barr WT.Cellular Pathology Technique. London: Butterworth. (1985); pp.281-290.
12-Yang Y, Ziyi LI, Xupeng WU. Direct reprogramming of mouse fibroblasts toward Leydig-like cells by defined factors. Stem cell reports. (2017); 8(1): 39-53.