Microanatomical study of testis in juvenile ostrich (Struthio camelus)

Abstract

The majority of investigations on the testis, as the main organ of male reproductive system, have been performed in mammalian species, with few studies on bird species. Thus, the structure of the ostrich testis remains largely unknown. The aim of this study was to investigate the microanatomical characteristics of the testis in five juvenile ostriches. A stereological study was performed according to the Delesse principle. The mean volume fraction of the seminiferous tubules was 0.569, and the mean volume of the seminiferous tubules in an average testis was 1.04 cm(3). The Paraffin-embedded sections were stained with hematoxylin and eosin, Masson's trichrome, Alcian blue, and periodic acid-Schiff stains. Histological studies revealed that the spermatogonial stem cells and Sertoli cells were localized inside the seminiferous tubules, close to the basement membrane. Inside the tubules a few meiotic cells up to the spermatozoa stage were located in a centripetal manner. Outside the tubules, one to three layers of euchromatic peritubular myoid cells were present, surrounded by loose interstitial connective tissue. A thick tunica albuginea contained many myoid cells and some rete ducts, with the latter extending from the hilus to the free surface of the testis. Straight seminiferous tubules were distributed in the lateral surfaces and hilar portions of the capsule but were rare in the free surface. These capsular rete ducts may participate in testicular fluid transit from the distal tubules through the capsule.

Comparison of embryonic development, fromHH21toHH40, between ostrich (Struthio camelus) and chicken (Gallus gallus)

“…At present, most research on ostriches has focused on its limbs, especially the shape and skeletal structures of its hind limbs 30‐32 . In the area of development, with increased availability due to artificial breeding, the ostrich has recently become a popular model animal, with the development of its stomach, testis, testicular capsule and rete ducts being studied 33‐35 . Although there have been a few studies on embryonic development in the ostrich, they have wide sampling intervals that result in a limited description of its embryonic stages, 20‐22 and no stage system corresponding to the chicken HH system has yet been established.…”

“…[30][31][32] In the area of development, with increased availability due to artificial breeding, the ostrich has recently become a popular model animal, with the development of its stomach, testis, testicular capsule and rete ducts being studied. [33][34][35] Although there have been a few studies on embryonic development in the ostrich, they have wide sampling intervals that result in a limited description of its embryonic stages, [20][21][22] and no stage system corresponding to the chicken HH system has yet been established. Thus, comparative studies between ostrich and chickens, or other birds, are limited, and key development stages may be missed.…”

Applications of various stereological tools for estimation of biological tissues

“…In 1843, Mining geologist Delete invented the first technique (Delesse's principle) for determining volume fraction in 3D from area fraction on sections; more simply, the principle rule as ‘the area fraction is equal to the volume fraction’ (Mandarim‐de‐Lacerda, 2003; Vikhreva et al, 2016). To estimate different organs, for example the cytoplasmic organelles' density and the seminiferous tubules' volume (Hassanzadeh et al, 2013). It is based on homogenous structures (in stereological viewpoint in ‘isotropic and uniform random, IUR, sections’).…”